a6

assignment5/Question2/StartGrading.java

@@ -4,34 +4,32 @@ public class StartGrading {
 //The Vehicle class is abstract. We cannot create objects from this class. Therefore, we cannot test anything
 	}
 
-
 	public static void testCar() {
 		// test case for constructors
 		try {
-// exception
+			// exception
 			Car c1 = new Car(70, 80);
 		} catch (BadSpeedSetting e) {
 			System.out.println(e.getMessage().equals("Speed cannot be greater than speed limit!"));
 		}
 		try {
-// exception
+			// exception
 			Car c2 = new Car(70, -10);
 		} catch (BadSpeedSetting e) {
 			System.out.println(e.getMessage().equals("Speed cannot be negative!"));
 		}
-// test case for accelerate, canFly and getSpeed methods
+		// test case for accelerate, canFly and getSpeed methods
 		try {
 			Car c3 = new Car(100, 80);
-// test the canFly method
+			// test the canFly method
 			System.out.println(c3.canFly() == false);
 			c3.accelerate(10);
 			System.out.println(c3.getSpeed() == 90);
-// test the accelerate with positive amount
+			// test the accelerate with positive amount
 			c3.accelerate(-20);
 			System.out.println(c3.getSpeed() == 70);
-// test the accelerate with negative amount 
-			c3.accelerate(35);
-// exception 
+			// test the accelerate with negative amount
+			c3.accelerate(35); // exception
 		} catch (BadSpeedSetting e) {
 			System.out.println("BUG! THIS MUST NEVER HAPPEN!");
 		} catch (ExceedSpeedLimit e) {
@@ -42,7 +40,7 @@ public class StartGrading {
 		}
 		try {
 			Car c4 = new Car(100, 80);
-// exception
+			// exception
 			c4.accelerate(-90);
 		} catch (BadSpeedSetting e) {
 			System.out.println("BUG! THIS MUST NEVER HAPPEN!");

assignment5/Question3/StartGrading.java

@@ -7,30 +7,29 @@ public class StartGrading {
 	public static void testCar() {
 		// test case for constructors
 		try {
-// exception
+			// exception
 			Car c1 = new Car(70, 80);
 		} catch (BadSpeedSetting e) {
 			System.out.println(e.getMessage().equals("Speed cannot be greater than speed limit!"));
 		}
 		try {
-// exception
+			// exception
 			Car c2 = new Car(70, -10);
 		} catch (BadSpeedSetting e) {
 			System.out.println(e.getMessage().equals("Speed cannot be negative!"));
 		}
-// test case for accelerate, canFly and getSpeed methods
+		// test case for accelerate, canFly and getSpeed methods
 		try {
 			Car c3 = new Car(100, 80);
-// test the canFly method
+			// test the canFly method
 			System.out.println(c3.canFly() == false);
 			c3.accelerate(10);
 			System.out.println(c3.getSpeed() == 90);
-// test the accelerate with positive amount
+			// test the accelerate with positive amount
 			c3.accelerate(-20);
 			System.out.println(c3.getSpeed() == 70);
-// test the accelerate with negative amount 
-			c3.accelerate(35);
-// exception 
+			// test the accelerate with negative amount
+			c3.accelerate(35); // exception
 		} catch (BadSpeedSetting e) {
 			System.out.println("BUG! THIS MUST NEVER HAPPEN!");
 		} catch (ExceedSpeedLimit e) {
@@ -41,7 +40,7 @@ public class StartGrading {
 		}
 		try {
 			Car c4 = new Car(100, 80);
-// exception
+			// exception
 			c4.accelerate(-90);
 		} catch (BadSpeedSetting e) {
 			System.out.println("BUG! THIS MUST NEVER HAPPEN!");

assignment5/Question4/StartGrading.java

@@ -1,3 +1,4 @@
+//Q4
 public class StartGrading {
 	public static void testVehicle() {
 //The Vehicle class is abstract. We cannot create objects from this class. Therefore, we cannot test anything
@@ -6,30 +7,29 @@ public class StartGrading {
 	public static void testCar() {
 		// test case for constructors
 		try {
-// exception
+			// exception
 			Car c1 = new Car(70, 80);
 		} catch (BadSpeedSetting e) {
 			System.out.println(e.getMessage().equals("Speed cannot be greater than speed limit!"));
 		}
 		try {
-// exception
+			// exception
 			Car c2 = new Car(70, -10);
 		} catch (BadSpeedSetting e) {
 			System.out.println(e.getMessage().equals("Speed cannot be negative!"));
 		}
-// test case for accelerate, canFly and getSpeed methods
+		// test case for accelerate, canFly and getSpeed methods
 		try {
 			Car c3 = new Car(100, 80);
-// test the canFly method
+			// test the canFly method
 			System.out.println(c3.canFly() == false);
 			c3.accelerate(10);
 			System.out.println(c3.getSpeed() == 90);
-// test the accelerate with positive amount
+			// test the accelerate with positive amount
 			c3.accelerate(-20);
 			System.out.println(c3.getSpeed() == 70);
-// test the accelerate with negative amount 
-			c3.accelerate(35);
-// exception 
+			// test the accelerate with negative amount
+			c3.accelerate(35); // exception
 		} catch (BadSpeedSetting e) {
 			System.out.println("BUG! THIS MUST NEVER HAPPEN!");
 		} catch (ExceedSpeedLimit e) {
@@ -37,10 +37,12 @@ public class StartGrading {
 					.println(e.getMessage().equals("Current speed is 70. Accelerate 35 will exceed the speed limit!"));
 		} catch (NotEnoughSpeed e) {
 			System.out.println("BUG! THIS MUST NEVER HAPPEN!");
+		} catch (TrainSpeedChange e) {
+			System.out.println("BUG! THIS MUST NEVER HAPPEN!");
 		}
 		try {
 			Car c4 = new Car(100, 80);
-// exception
+			// exception
 			c4.accelerate(-90);
 		} catch (BadSpeedSetting e) {
 			System.out.println("BUG! THIS MUST NEVER HAPPEN!");
@@ -48,6 +50,8 @@ public class StartGrading {
 			System.out.println("BUG! THIS MUST NEVER HAPPEN!");
 		} catch (NotEnoughSpeed e) {
 			System.out.println(e.getMessage().equals("Current speed is " + 80 + ", not enough speed to decelerate!"));
+		} catch (TrainSpeedChange e) {
+			System.out.println("BUG! THIS MUST NEVER HAPPEN!");
 		}
 	}
 
@@ -101,6 +105,8 @@ public class StartGrading {
 					e.getMessage().equals("Current speed is 100. Accelerate 650 will exceed the speed limit!"));
 		} catch (NotEnoughSpeed e) {
 			System.out.println("BUG! THIS MUST NEVER HAPPEN!");
+		} catch (TrainSpeedChange e) {
+			System.out.println("BUG! THIS MUST NEVER HAPPEN!");
 		}
 		try {
 			Aircraft a5 = new Aircraft(700, 200, 100);
@@ -114,6 +120,8 @@ public class StartGrading {
 			System.out.println("BUG! THIS MUST NEVER HAPPEN!");
 		} catch (NotEnoughSpeed e) {
 			System.out.println(e.getMessage().equals("Current speed is " + 200 + ", not enough speed to decelerate!"));
+		} catch (TrainSpeedChange e) {
+			System.out.println("BUG! THIS MUST NEVER HAPPEN!");
 		}
 	}
 
@@ -123,7 +131,7 @@ public class StartGrading {
 			// exception
 			Train t1 = new Train(350, 400);
 		} catch (BadSpeedSetting e) {
-			System.out.println(e.getMessage().equals("Speed cannot be greater than	speed limit!"));
+			System.out.println(e.getMessage().equals("Speed cannot be greater than speed limit!"));
 		}
 		try {
 			// exception
@@ -150,7 +158,7 @@ public class StartGrading {
 	public static void main(String[] args) {
 		Vehicle.testVehicle();
 		Car.testCar();
-		AirCraft.testAirCraft();
+		Aircraft.testAircraft();
 		Train.testTrain();
 	}
 }

assignment5/Question5/ManyVehicles.java

@@ -31,7 +31,7 @@ public class ManyVehicles {
 	 *
 	 * @return the average speed of all vehicles
 	 */
-	public double averageSpeed() {
+	public double calcAvgSpeed() {
 		double totalSpeed = 0;
 		for (Vehicle v : vehicles) {
 			totalSpeed += v.getSpeed();
@@ -50,7 +50,7 @@ public class ManyVehicles {
 			mv.addVehicle(new Aircraft(100, 70, 3900));
 			mv.addVehicle(new Train(100, 60));
 
-			System.out.println(mv.averageSpeed() == 80.0);
+			System.out.println(mv.calcAvgSpeed() == 80.0);
 		} catch (Exception e) {
 			System.out.println("Error uncaught exception: " + e.getClass().getName() + e.getMessage());
 		}

assignment5/Question5/StartGrading.java

@@ -1,3 +1,4 @@
+//Q5
 public class StartGrading {
 	public static void testVehicle() {
 //The Vehicle class is abstract. We cannot create objects from this class. Therefore, we cannot test anything
@@ -6,30 +7,29 @@ public class StartGrading {
 	public static void testCar() {
 		// test case for constructors
 		try {
-// exception
+			// exception
 			Car c1 = new Car(70, 80);
 		} catch (BadSpeedSetting e) {
 			System.out.println(e.getMessage().equals("Speed cannot be greater than speed limit!"));
 		}
 		try {
-// exception
+			// exception
 			Car c2 = new Car(70, -10);
 		} catch (BadSpeedSetting e) {
 			System.out.println(e.getMessage().equals("Speed cannot be negative!"));
 		}
-// test case for accelerate, canFly and getSpeed methods
+		// test case for accelerate, canFly and getSpeed methods
 		try {
 			Car c3 = new Car(100, 80);
-// test the canFly method
+			// test the canFly method
 			System.out.println(c3.canFly() == false);
 			c3.accelerate(10);
 			System.out.println(c3.getSpeed() == 90);
-// test the accelerate with positive amount
+			// test the accelerate with positive amount
 			c3.accelerate(-20);
 			System.out.println(c3.getSpeed() == 70);
-// test the accelerate with negative amount 
-			c3.accelerate(35);
-// exception 
+			// test the accelerate with negative amount
+			c3.accelerate(35); // exception
 		} catch (BadSpeedSetting e) {
 			System.out.println("BUG! THIS MUST NEVER HAPPEN!");
 		} catch (ExceedSpeedLimit e) {
@@ -37,10 +37,12 @@ public class StartGrading {
 					.println(e.getMessage().equals("Current speed is 70. Accelerate 35 will exceed the speed limit!"));
 		} catch (NotEnoughSpeed e) {
 			System.out.println("BUG! THIS MUST NEVER HAPPEN!");
+		} catch (TrainSpeedChange e) {
+			System.out.println("BUG! THIS MUST NEVER HAPPEN!");
 		}
 		try {
 			Car c4 = new Car(100, 80);
-// exception
+			// exception
 			c4.accelerate(-90);
 		} catch (BadSpeedSetting e) {
 			System.out.println("BUG! THIS MUST NEVER HAPPEN!");
@@ -48,6 +50,8 @@ public class StartGrading {
 			System.out.println("BUG! THIS MUST NEVER HAPPEN!");
 		} catch (NotEnoughSpeed e) {
 			System.out.println(e.getMessage().equals("Current speed is " + 80 + ", not enough speed to decelerate!"));
+		} catch (TrainSpeedChange e) {
+			System.out.println("BUG! THIS MUST NEVER HAPPEN!");
 		}
 	}
 
@@ -101,6 +105,8 @@ public class StartGrading {
 					e.getMessage().equals("Current speed is 100. Accelerate 650 will exceed the speed limit!"));
 		} catch (NotEnoughSpeed e) {
 			System.out.println("BUG! THIS MUST NEVER HAPPEN!");
+		} catch (TrainSpeedChange e) {
+			System.out.println("BUG! THIS MUST NEVER HAPPEN!");
 		}
 		try {
 			Aircraft a5 = new Aircraft(700, 200, 100);
@@ -114,6 +120,8 @@ public class StartGrading {
 			System.out.println("BUG! THIS MUST NEVER HAPPEN!");
 		} catch (NotEnoughSpeed e) {
 			System.out.println(e.getMessage().equals("Current speed is " + 200 + ", not enough speed to decelerate!"));
+		} catch (TrainSpeedChange e) {
+			System.out.println("BUG! THIS MUST NEVER HAPPEN!");
 		}
 	}
 
@@ -123,7 +131,7 @@ public class StartGrading {
 			// exception
 			Train t1 = new Train(350, 400);
 		} catch (BadSpeedSetting e) {
-			System.out.println(e.getMessage().equals("Speed cannot be greater than	speed limit!"));
+			System.out.println(e.getMessage().equals("Speed cannot be greater than speed limit!"));
 		}
 		try {
 			// exception
@@ -149,7 +157,7 @@ public class StartGrading {
 
 	public static void testManyVehicles() {
 		ManyVehicles mv = new ManyVehicles();
-		// Add any kind of vehicles to the arraylist.
+// Add any kind of vehicles to the arraylist.
 		try {
 			Train t = new Train(350, 300);
 			mv.addVehicle(t);
@@ -163,7 +171,7 @@ public class StartGrading {
 			System.out.println("BUG! THIS MUST NEVER HAPPEN!");
 		}
 		try {
-			AirCraft a = new AirCraft(700, 200, 100);
+			Aircraft a = new Aircraft(700, 200, 100);
 			mv.addVehicle(a);
 		} catch (BadSpeedSetting e) {
 			System.out.println("BUG! THIS MUST NEVER HAPPEN!");
@@ -176,8 +184,7 @@ public class StartGrading {
 	public static void main(String[] args) {
 		Vehicle.testVehicle();
 		Car.testCar();
-		AirCraft.testAirCraft();
+		Aircraft.testAircraft();
 		Train.testTrain();
-		ManyVehicles.testVehicles();
 	}
 }

assignment6/Question1/IShape.java

@@ -0,0 +1,17 @@
+import java.awt.Graphics;
+
+public interface IShape {
+	public int getX();
+
+	public int getY();
+
+	public void setX(int x);
+
+	public void setY(int y);
+
+	public boolean isVisible(int w, int h);
+
+	public boolean isIn(int x, int y);
+
+	public void draw(Graphics g);
+}

assignment6/Question1/Shape.java

@@ -0,0 +1,51 @@
+import java.awt.Color;
+import java.awt.Graphics;
+
+public abstract class Shape {
+	private int x;
+	private int y;
+	private Color color;
+
+	/**
+	 * Constructor for Shape
+	 *
+	 * @param x
+	 * 	  the x coordinate of the shape
+	 * @param y
+	 * 	  the y coordinate of the shape
+	 */
+	public Shape(int x, int y) {
+		this.x = x;
+		this.y = y;
+		color = new Color((float) Math.random(), (float) Math.random(), (float) Math.random());
+	}
+
+	public int getX() {
+		return x;
+	}
+
+	public void setX(int x) {
+		this.x = x;
+	}
+
+	public int getY() {
+		return y;
+	}
+
+	public void setY(int y) {
+		this.y = y;
+	}
+
+	public abstract boolean isVisible(int w, int h);
+
+	public abstract boolean isIn(int x, int y);
+
+	public void draw(Graphics g) {
+		g.setColor(color);
+	}
+
+	public static void testShape() {
+		// TODO: implement this method
+		// Because this is the abstract so we don't test anything here.
+	}
+}

assignment6/Question1/Start.java

@@ -0,0 +1,5 @@
+public class Start {
+	public static void main(String[] args) {
+		Shape.testShape();
+	}
+}

assignment6/Question2/Bubble.java

@@ -0,0 +1,89 @@
+import java.awt.Graphics;
+
+public class Bubble extends Shape {
+	private double radius;
+
+	/**
+	 * Constructor for the Bubble class.
+	 *
+	 * @param x the x coordinate of the center of the bubble
+	 * @param y the y coordinate of the center of the bubble
+	 */
+	public Bubble(int x, int y) {
+		super(x, y);
+		this.radius = 10;
+	}
+
+	// Find the point (wx, wy) inside the window which is closest to the
+	// center (x, y) of the circle. In other words, find the wx in the
+	// interval [0, w - 1] which is closest to x, and find the wy in the
+	// interval [0, h - 1] which is closest to y.
+	// If the distance between (wx, wy) and (x, y) is less than the radius
+	// of the circle (using Pythagoras's theorem) then at least part of
+	// the circle is visible in the window.
+	// Note: if the center of the circle is inside the window, then (wx, wy)
+	// is the same as (x, y), and the distance is 0.
+	@Override
+	public boolean isVisible(int w, int h) {
+		double x = getX();
+		double y = getY();
+		double wx = (x < 0 ? 0 : (x > w - 1 ? w - 1 : x));
+		double wy = (y < 0 ? 0 : (y > h - 1 ? h - 1 : y));
+		double dx = wx - x;
+		double dy = wy - y;
+		return dx * dx + dy * dy <= radius * radius;
+	}
+
+	/**
+	 * Whether the point at xy is currently inside the bubble
+	 *
+	 * @param x the x coordinate of the point
+	 * @param y the y coordinate of the point
+	 * @return true if the point is inside the bubble, false otherwise
+	 */
+	@Override
+	public boolean isIn(int x, int y) {
+		double dx = x - getX();
+		double dy = y - getY();
+		return dx * dx + dy * dy < radius * radius;
+	}
+
+	/**
+	 * Draw the bubble.
+	 *
+	 * @param g the graphics context
+	 */
+	@Override
+	public void draw(Graphics g) {
+		super.draw(g);
+		g.drawOval(
+				getX() - (int) radius,
+				getY() - (int) radius,
+				(int) radius * 2,
+				(int) radius * 2);
+	}
+
+	public static void testBubble() {
+		Bubble b = new Bubble(20, 30);
+
+		System.out.println(b.getX() == 20);
+		System.out.println(b.getY() == 30);
+
+		b.setX(40);
+		System.out.println(b.getX() == 40);
+		System.out.println(b.getY() == 30);
+
+		b.setY(60);
+		System.out.println(b.getX() == 40);
+		System.out.println(b.getY() == 60);
+		System.out.println(b.isVisible(100, 100) == true);
+
+		b.setX(50);
+		b.setY(0);
+		System.out.println(b.isVisible(100, 100) == true);
+
+		b.setX(99);
+		b.setY(50);
+		System.out.println(b.isVisible(100, 100) == true);
+	}
+}

assignment6/Question2/IShape.java

@@ -0,0 +1,17 @@
+import java.awt.Graphics;
+
+public interface IShape {
+	public int getX();
+
+	public int getY();
+
+	public void setX(int x);
+
+	public void setY(int y);
+
+	public boolean isVisible(int w, int h);
+
+	public boolean isIn(int x, int y);
+
+	public void draw(Graphics g);
+}

assignment6/Question2/Shape.java

@@ -0,0 +1,42 @@
+import java.awt.Color;
+import java.awt.Graphics;
+
+public abstract class Shape {
+	private int x;
+	private int y;
+	private Color color;
+
+	public Shape(int x, int y) {
+		this.x = x;
+		this.y = y;
+		color = new Color((float) Math.random(), (float) Math.random(), (float) Math.random());
+	}
+
+	// getters and setters
+	public int getX() {
+		return x;
+	}
+
+	public void setX(int x) {
+		this.x = x;
+	}
+
+	public int getY() {
+		return y;
+	}
+
+	public void setY(int y) {
+		this.y = y;
+	}
+
+	public abstract boolean isVisible(int w, int h);
+
+	public abstract boolean isIn(int x, int y);
+
+	public void draw(Graphics g) {
+		g.setColor(color);
+	}
+
+	public static void testShape() {
+	}
+}

assignment6/Question2/Start.java

@@ -0,0 +1,6 @@
+public class Start {
+	public static void main(String[] args) {
+		Shape.testShape();
+		Bubble.testBubble();
+	}
+}

assignment6/Question3/Bubble.java

@@ -0,0 +1,65 @@
+import java.awt.Graphics;
+
+public class Bubble extends Shape implements IShape {
+	// instance variables
+	private double radius;
+
+	// constructor
+	public Bubble(int x, int y) {
+		super(x, y);
+		this.radius = 10;
+	}
+
+	// Find the point (wx, wy) inside the window which is closest to the
+	// center (x, y) of the circle. In other words, find the wx in the
+	// interval [0, w - 1] which is closest to x, and find the wy in the
+	// interval [0, h - 1] which is closest to y.
+	// If the distance between (wx, wy) and (x, y) is less than the radius
+	// of the circle (using Pythagoras's theorem) then at least part of
+	// the circle is visible in the window.
+	// Note: if the center of the circle is inside the window, then (wx, wy)
+	// is the same as (x, y), and the distance is 0.
+	@Override
+	public boolean isVisible(int w, int h) {
+		double x = getX();
+		double y = getY();
+		double wx = (x < 0 ? 0 : (x > w - 1 ? w - 1 : x));
+		double wy = (y < 0 ? 0 : (y > h - 1 ? h - 1 : y));
+		double dx = wx - x;
+		double dy = wy - y;
+		return dx * dx + dy * dy <= radius * radius;
+	}
+
+	@Override
+	public boolean isIn(int x, int y) {
+		double dx = x - getX();
+		double dy = y - getY();
+		return dx * dx + dy * dy < radius * radius;
+	}
+
+	@Override
+	public void draw(Graphics g) {
+		super.draw(g);
+		g.drawOval(
+				getX() - (int) radius,
+				getY() - (int) radius,
+				(int) radius * 2,
+				(int) radius * 2);
+	}
+
+	public static void testBubble() {
+		Bubble b = new Bubble(20, 30);
+		System.out.println(b.getX() == 20);
+		System.out.println(b.getY() == 30);
+		b.setX(40);
+		System.out.println(b.getX() == 40);
+		System.out.println(b.getY() == 30);
+		b.setY(60);
+		System.out.println(b.getX() == 40);
+		System.out.println(b.getY() == 60);
+		System.out.println(b.isVisible(100, 100) == true);
+		b.setX(50);
+		b.setY(0);
+		System.out.println(b.isVisible(100, 100) == true);
+	}
+}

assignment6/Question3/IShape.java

@@ -0,0 +1,17 @@
+import java.awt.Graphics;
+
+public interface IShape {
+	public int getX();
+
+	public int getY();
+
+	public void setX(int x);
+
+	public void setY(int y);
+
+	public boolean isVisible(int w, int h);
+
+	public boolean isIn(int x, int y);
+
+	public void draw(Graphics g);
+}

assignment6/Question3/Model.java

@@ -0,0 +1,105 @@
+import java.awt.Graphics;
+import java.util.ArrayList;
+
+public class Model {
+	// instance variables
+	private int score;
+	private ArrayList<IShape> bubbles;
+
+	// constructor
+	public Model() {
+		score = 0;
+		bubbles = new ArrayList<IShape>();
+	}
+
+	// getters and setters
+	public int getScore() {
+		return score;
+	}
+
+	/**
+	 * @param w
+	 * @param h
+	 */
+	public void addBubble(int w, int h) {
+		bubbles.add(new Bubble((int) (w * Math.random()), (int) (h * Math.random())));
+	}
+
+	/**
+	 * @param dx
+	 * @param dy
+	 */
+	public void moveAll(int dx, int dy) {
+		for (int i = 0; i < bubbles.size(); i++) {
+			bubbles.get(i).setX(bubbles.get(i).getX() + dx);
+			bubbles.get(i).setY(bubbles.get(i).getY() + dy);
+		}
+	}
+
+	/**
+	 * clear all bubbles
+	 * 
+	 * @param w
+	 * @param h
+	 */
+	public void clearInvisibles(int w, int h) {
+		for (int i = bubbles.size() - 1; i >= 0; i--) {
+			if (!bubbles.get(i).isVisible(w, h)) {
+				bubbles.remove(i);
+				score--;
+			}
+		}
+	}
+
+	/**
+	 * delete bubbles that are hit by the mouse
+	 * 
+	 * @param x
+	 * @param y
+	 */
+	public void deleteBubblesAtPoint(int x, int y) {
+		for (int i = bubbles.size() - 1; i >= 0; i--) {
+			if (bubbles.get(i).isIn(x, y)) {
+				bubbles.remove(i);
+				score++;
+			}
+		}
+	}
+
+	/**
+	 * draw all bubbles
+	 *
+	 * @param g
+	 */
+	public void drawAll(Graphics g) {
+		for (IShape bubble : bubbles) {
+			bubble.draw(g);
+		}
+	}
+
+	public static void testModel() {
+		Model m = new Model();
+		System.out.println(m.getScore() == 0);
+		System.out.println(m.bubbles.size() == 0);
+		m.addBubble(100, 100);
+		m.addBubble(100, 100);
+		System.out.println(m.getScore() == 0);
+		System.out.println(m.bubbles.size() == 2);
+		m.clearInvisibles(200, 200);
+		System.out.println(m.getScore() == 0);
+		System.out.println(m.bubbles.size() == 2);
+		m.clearInvisibles(0, 0);
+		System.out.println(m.getScore() == -2);
+		System.out.println(m.bubbles.size() == 0);
+		m.addBubble(100, 100);
+		m.addBubble(100, 100);
+		System.out.println(m.getScore() == -2);
+		System.out.println(m.bubbles.size() == 2);
+		m.moveAll(200, 200);
+		System.out.println(m.getScore() == -2);
+		System.out.println(m.bubbles.size() == 2);
+		m.clearInvisibles(200, 200);
+		System.out.println(m.getScore() == -4);
+		System.out.println(m.bubbles.size() == 0);
+	}
+}

assignment6/Question3/Shape.java

@@ -0,0 +1,41 @@
+import java.awt.Color;
+import java.awt.Graphics;
+
+public abstract class Shape {
+	private int x;
+	private int y;
+	private Color color;
+
+	public Shape(int x, int y) {
+		this.x = x;
+		this.y = y;
+		color = new Color((float) Math.random(), (float) Math.random(), (float) Math.random());
+	}
+
+	public int getX() {
+		return x;
+	}
+
+	public void setX(int x) {
+		this.x = x;
+	}
+
+	public int getY() {
+		return y;
+	}
+
+	public void setY(int y) {
+		this.y = y;
+	}
+
+	public abstract boolean isVisible(int w, int h);
+
+	public abstract boolean isIn(int x, int y);
+
+	public void draw(Graphics g) {
+		g.setColor(color);
+	}
+
+	public static void testShape() {
+	}
+}

assignment6/Question3/Start.java

@@ -0,0 +1,7 @@
+public class Start {
+	public static void main(String[] args) {
+		Shape.testShape();
+		Bubble.testBubble();
+		Model.testModel();
+	}
+}

finalproject/Question1/IUser.java

@@ -0,0 +1,13 @@
+/*
+ * Author: CHEN Yongyuan (Walter) 1930006025 from OOP(1007)
+ * Date: 2022-04-25
+ * Description: This is the interface of IUser.
+ */
+
+public interface IUser {
+	public String getName();
+
+	public int getBook();
+
+	public void moreBook(int number);
+}

finalproject/Question1/Test.java

@@ -0,0 +1,5 @@
+public class Test {
+	public static void main(String[] args) {
+		User.testUser();
+	}
+}

finalproject/Question1/User.java

@@ -0,0 +1,78 @@
+/*
+ * Author: CHEN Yongyuan (Walter) 1930006025 from OOP(1007)
+ * Date: 2022-04-25
+ * Description: This is the User class.
+ */
+
+public abstract class User implements IUser {
+	/**
+	 * The user's name.
+	 */
+	private String name;
+
+	/**
+	 * The number of books borrowed by the user.
+	 */
+	private int book;
+
+	/**
+	 * Constructor.
+	 *
+	 * @param name The user's name.
+	 * @param book The number of books borrowed by the user.
+	 */
+	public User(String name, int book) {
+		this.name = name;
+		this.book = book;
+	}
+
+	/**
+	 * Getter of the user's name.
+	 *
+	 * @return The user's name.
+	 */
+	public String getName() {
+		return name;
+	}
+
+	/**
+	 * Getter of the number of books borrowed by the user.
+	 *
+	 * @return The number of books borrowed by the user.
+	 */
+	public int getBook() {
+		return book;
+	}
+
+	/**
+	 * Change the number of books borrowed by the user.
+	 *
+	 * @param book The number of books borrowed by the user.
+	 */
+	protected void setBook(int book) {
+		this.book = book;
+	}
+
+	/**
+	 * Increase the number of books borrowed by the user.
+	 *
+	 * @param book The number of books borrowed by the user.
+	 */
+	public abstract void moreBook(int number);
+
+	/**
+	 * Test.
+	 */
+	public static void testUser() {
+		User user = new User("Walter", 3) {
+			@Override
+			public void moreBook(int number) {
+				setBook(getBook() + number);
+			}
+		};
+		System.out.println(user.getName() == "Walter");
+		System.out.println(user.getBook() == 3);
+		user.moreBook(2);
+		System.out.println(user.getBook() == 5);
+	}
+}

finalproject/Question10/Borrower.java

@@ -0,0 +1,63 @@
+/*
+ * Author: CHEN Yongyuan (Walter) 1930006025 from OOP(1007)
+ * Date: 2022-04-25
+ * Description: This is the borrower class.
+ */
+
+public class Borrower extends User {
+	/**
+	 * Constructor.
+	 *
+	 * @param name Borrower's name
+	 * @param int  book number of books borrowed by user
+	 */
+	public Borrower(String name, int book) throws NotALenderException {
+		super(name, book);
+
+		// check
+		if (book < 0) {
+			throw new NotALenderException("A new borrower cannot lend books.");
+		}
+	}
+
+	/**
+	 * increase the number of books borrowed by the user.
+	 *
+	 * @param number Incrased number of books
+	 * @throws NotALenderException
+	 */
+	public void moreBook(int number) throws NotALenderException {
+		int newBook = getBook() + number;
+		if (number < 0 && newBook < 0) {
+			throw new NotALenderException("A borrower cannot lend " + (-newBook) + " book(s).");
+		}
+		setBook(newBook);
+	}
+
+	/**
+	 * Test.
+	 */
+	public static void testBorrower() {
+		try {
+			Borrower b = new Borrower("Bob", -1);
+		} catch (NotALenderException e) {
+			System.out.println(e.getMessage().equals("A new borrower cannot lend books."));
+		}
+		try {
+			Borrower b = new Borrower("Bob", 10);
+			System.out.println(b.getName() == "Bob");
+			System.out.println(b.getBook() == 10);
+			b.setBook(5);
+			System.out.println(b.getBook() == 5);
+			b.moreBook(2);
+			System.out.println(b.getBook() == 7);
+			b.moreBook(-2);
+			System.out.println(b.getBook() == 5);
+			b.moreBook(-5);
+			System.out.println(b.getBook() == 0);
+			b.moreBook(-1);
+		} catch (NotALenderException e) {
+			System.out.println(e.getMessage().equals("A borrower cannot lend 1 book(s)."));
+		}
+	}
+}

finalproject/Question10/CLI.java

@@ -0,0 +1,145 @@
+/*
+ * Author: CHEN Yongyuan (Walter) 1930006025 from OOP(1007)
+ * Date: 2022-04-25
+ * Description: This is the CLI class.
+ */
+
+import java.util.InputMismatchException;
+import java.util.Scanner;
+
+public class CLI {
+	private static Scanner input = new Scanner(System.in);
+
+	/**
+	 * Read one line from CLI.
+	 *
+	 * @param message Hint printed to screen
+	 * @return one line input
+	 */
+	private static String readLine(String message) {
+		System.out.print(message);
+		return input.nextLine();
+	}
+
+	/**
+	 * Read one positive integer.
+	 *
+	 * @param message HINT printed to screen
+	 * @return one positive integer
+	 */
+	private static int readPosInt(String message) {
+		while (true) {
+			System.out.print(message);
+			try {
+				int result = input.nextInt();
+				input.nextLine();
+				if (result >= 0) {
+					return result;
+				} else {
+					System.out.println("Positive integers only!");
+				}
+			} catch (InputMismatchException e) {
+				System.out.println("You must type an integer!");
+				input.nextLine();
+			}
+		}
+	}
+
+	public static void main(String[] args) {
+		int book;
+		String username;
+		String menuHint = "Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): ";
+		String userRoleHint = "Type the user role (lender:1 borrower:2): ";
+
+		Library library = new Library("UIC Library");
+		while (true) {
+			switch (readPosInt(menuHint)) {
+				// total
+				case 1:
+					System.out.println("Total number of borrowed books: "
+							+ library.totalBorrowedBooks());
+					break;
+				// add
+				case 2:
+					switch (readPosInt(userRoleHint)) {
+						// lender
+						case 1:
+							username = readLine("Enter the name of the user: ");
+							book = readPosInt(
+									"Enter the initial number of borrowed books: ");
+							Lender lender = new Lender(username, book);
+							library.addUser(lender);
+							System.out.println("Lender \"" + username + "\" lending " + book
+									+ " book(s) has been added.");
+							break;
+						// borrower
+						case 2:
+							username = readLine(
+									"Enter the name of the user: ");
+							book = readPosInt(
+									"Enter the initial number of borrowed books: ");
+							try {
+								library.addUser(new Borrower(username, book));
+								System.out.println("Borrower \""
+										+ username
+										+ "\" borrowing "
+										+ book
+										+ " book(s) has been added.");
+							} catch (NotALenderException e) {
+								System.out.println("BUG! This must never happen!");
+								System.exit(1);
+							}
+							break;
+						default:
+							System.out.println("Unknown user role!");
+							break;
+					}
+					break;
+				// get
+				case 3:
+					username = readLine("Enter the name of the user: ");
+					try {
+						System.out.println(username + " borrows "
+								+ library.getBook(username) + " book(s).");
+					} catch (UnknownUserException e) {
+						System.out.println("User " + username + " unknown.");
+					}
+					break;
+				case 4:
+					username = readLine("Enter the name of the user: ");
+					book = readPosInt("Enter the number of books: ");
+					try {
+						library.moreBook(username, book);
+					} catch (NotALenderException e) {
+						System.out.println("BUG! This must never happen!");
+					} catch (UnknownUserException e) {
+						System.out.println("User " + username + " unknown.");
+					}
+					break;
+				case 5:
+					username = readLine("Enter the name of the user: ");
+					book = readPosInt("Enter the number of books: ");
+					try {
+						// decrease numbers
+						try {
+							library.moreBook(username, -book);
+						} catch (NotALenderException e) {
+							System.out.println("A borrower cannot lend "
+									+ (-(library.getBook(username) - book))
+									+ " book(s).");
+						}
+					} catch (UnknownUserException e) {
+						System.out.println("User " + username + " unknown.");
+					}
+					break;
+				case 6:
+					System.out.println("Goodbye!");
+					System.exit(0);
+					break;
+				default:
+					System.out.println("Unknown action!");
+					break;
+			}
+		}
+	}
+}

finalproject/Question10/Controller.java

@@ -0,0 +1,7 @@
+public class Controller {
+	protected Library m;
+
+	public Controller(Library m) {
+		this.m = m;
+	}
+}

finalproject/Question10/ControllerGetBook.java

@@ -0,0 +1,15 @@
+public class ControllerGetBook extends Controller {
+	public ControllerGetBook(Library m) {
+		super(m);
+	}
+
+	// get book
+	public String getBook(String name) {
+		try {
+			return Integer.toString(m.getBook(name));
+		} catch (UnknownUserException e) {
+			// return error message
+			return e.getMessage();
+		}
+	}
+}

finalproject/Question10/ControllerMoreBook.java

@@ -0,0 +1,27 @@
+public class ControllerMoreBook extends Controller {
+	// constr
+	public ControllerMoreBook(Library m) {
+		super(m);
+	}
+
+	/**
+	 * @param name the username
+	 * @param number the book number
+	 */
+	public String moreBook(String name, String number) {
+		try {
+			int num = Integer.parseInt(number);
+			m.moreBook(name, num);
+			return "";
+
+		} catch (UnknownUserException e) {
+			return e.getMessage();
+
+		} catch (NotALenderException e) {
+			return e.getMessage();
+
+		} catch (NumberFormatException e) {
+			return e.getMessage();
+		}
+	}
+}

finalproject/Question10/ControllerSimple.java

@@ -0,0 +1,12 @@
+/*
+ * Author: CHEN Yongyuan (Walter) 1930006025 from OOP(1007)
+ * Date: 2022-04-25
+ */
+
+public class ControllerSimple extends Controller {
+	private Library m;
+
+	public ControllerSimple(Library m) {
+		super(m);
+	}
+}

finalproject/Question10/GUI.java

@@ -0,0 +1,20 @@
+public class GUI {
+	public static void main(String[] args) {
+
+		// anonymous class
+		javax.swing.SwingUtilities.invokeLater(new Runnable() {
+			public void run() {
+				Library li = new Library("UIC Library");
+				ControllerSimple cs = new ControllerSimple(li);
+
+				ViewSimple vs = new ViewSimple(li, cs);
+				ControllerGetBook cgb = new ControllerGetBook(li);
+
+				ViewGetBook vgb = new ViewGetBook(li, cgb);
+				ControllerMoreBook cmb = new ControllerMoreBook(li);
+
+				ViewMoreBook vmb = new ViewMoreBook(li, cmb);
+			}
+		});
+	}
+}

finalproject/Question10/IUser.java

@@ -0,0 +1,13 @@
+/*
+ * Author: CHEN Yongyuan (Walter) 1930006025 from OOP(1007)
+ * Date: 2022-04-25
+ * Description: This is the interface of IUser.
+ */
+
+public interface IUser {
+	public String getName();
+
+	public int getBook();
+
+	public void moreBook(int number) throws NotALenderException;
+}

finalproject/Question10/Lender.java

@@ -0,0 +1,42 @@
+/*
+ * Author: CHEN Yongyuan (Walter) 1930006025 from OOP(1007)
+ * Date: 2022-04-25
+ * Description: This is the Lender class.
+ */
+
+public class Lender extends User {
+	/**
+	 * Constructor.
+	 *
+	 * @param name The user's name.
+	 * @param book number of bookds lent by the user. This will be store in negetive value.
+	 */
+	public Lender(String name, int book) {
+		// lender negetive book value
+		super(name, -book);
+	}
+
+	/**
+	 * Increases the number of bookds.
+	 *
+	 * @param book the number of books.
+	 */
+	public void moreBook(int book) {
+		setBook(getBook() - book);
+	}
+
+	/**
+	 * Test.
+	 */
+	public static void testLender() {
+		Lender l = new Lender("Anna", 5);
+		System.out.println(l.getName() == "Anna");
+		System.out.println(l.getBook() == -5);
+		l.setBook(-6);
+		System.out.println(l.getBook() == -6);
+		l.moreBook(2);
+		System.out.println(l.getBook() == -8);
+		l.moreBook(-9);
+		System.out.println(l.getBook() == 1);
+	}
+}

finalproject/Question10/Library.java

@@ -0,0 +1,122 @@
+/*
+ * Author: CHEN Yongyuan (Walter) 1930006025 from OOP(1007)
+ * Date: 2022-04-25
+ * Description: This is the Library class.
+ */
+
+import java.util.ArrayList;
+
+public class Library {
+	private String name;
+	private ArrayList<IUser> users;
+	private ArrayList<ModelListener> listeners;
+
+	/**
+	 * Constructor.
+	 *
+	 * @param name
+	 */
+	public Library(String name) {
+		this.name = name;
+
+		// init array list
+		this.users = new ArrayList<IUser>();
+		this.listeners = new ArrayList<ModelListener>();
+	}
+
+	// GUI Related
+	public void addListener(ModelListener listener) {
+		listeners.add(listener);
+	}
+
+	// GUI Related
+	private void notifyListeners() {
+		for (ModelListener listener : listeners) {
+			listener.update();
+		}
+	}
+
+	/**
+	 * Add the user to the array list.
+	 *
+	 * @param user The user to be added
+	 */
+	public void addUser(IUser user) {
+		users.add(user);
+		notifyListeners();
+	}
+
+	/**
+	 * The total number of bookds borrowed by all users.
+	 *
+	 * @return the number of books.
+	 */
+	public int totalBorrowedBooks() {
+		int total = 0;
+		for (IUser user : users) {
+			total += user.getBook();
+		}
+		return total;
+	}
+
+	/**
+	 * Get the number of books borrowed by this user.
+	 *
+	 * @param name the name of the query user
+	 * @return the number of books
+	 * @throws UnknownUserException if user not found
+	 */
+	public int getBook(String name) throws UnknownUserException {
+		for (IUser user : users) {
+			if (user.getName().equals(name)) {
+				return user.getBook();
+			}
+		}
+		// user not found
+		throw new UnknownUserException("User " + name + " unknown.");
+	}
+
+	/**
+	 * Change the number of books currently borrowed by that user.
+	 *
+	 * @param name   the user's name
+	 * @param number the number of books
+	 * @throws UnknownUserException user not found
+	 * @throws NotALenderException  can not lend book
+	 */
+	public void moreBook(String name, int number) throws UnknownUserException, NotALenderException {
+		for (IUser user : users) {
+			if (user.getName().equals(name)) {
+				user.moreBook(number);
+				notifyListeners();
+				return;
+			}
+		}
+		// user not found
+		throw new UnknownUserException("User " + name + " unknown.");
+	}
+
+	/**
+	 * Test.
+	 */
+	public static void testLibrary() {
+		Library li = new Library("UIC Library");
+		System.out.println(li.totalBorrowedBooks() == 0);
+		li.addUser(new Lender("L1", 10));
+		try {
+			System.out.println(li.getBook("L1") == -10);
+			System.out.println(li.totalBorrowedBooks() == -10);
+			li.addUser(new Borrower("B1", 20));
+			System.out.println(li.getBook("L1") == -10);
+			System.out.println(li.getBook("B1") == 20);
+			System.out.println(li.totalBorrowedBooks() == 10);
+			li.getBook("B2");
+		} catch (UnknownUserException ex) {
+			System.out.println(ex.getMessage().equals("User B2 unknown."));
+		} catch (NotALenderException ex) {
+			// This should never happen!
+			System.out.println(false);
+		}
+		// More test cases are needed
+	}
+}

finalproject/Question10/ModelListener.java

@@ -0,0 +1,3 @@
+public interface ModelListener {
+	public void update();
+}

finalproject/Question10/NotALenderException.java

@@ -0,0 +1,5 @@
+public class NotALenderException extends Exception {
+	public NotALenderException(String message) {
+		super(message);
+	}
+}

finalproject/Question10/Test.java

@@ -0,0 +1,8 @@
+public class Test {
+	public static void main(String[] args) {
+		User.testUser();
+		Lender.testLender();
+		Borrower.testBorrower();
+		Library.testLibrary();
+	}
+}

finalproject/Question10/UnknownUserException.java

@@ -0,0 +1,5 @@
+public class UnknownUserException extends Exception {
+	public UnknownUserException(String message) {
+		super(message);
+	}
+}

finalproject/Question10/User.java

@@ -0,0 +1,69 @@
+/*
+ * Author: CHEN Yongyuan (Walter) 1930006025 from OOP(1007)
+ * Date: 2022-04-25
+ * Description: This is the User class.
+ */
+
+public abstract class User implements IUser {
+	/**
+	 * The user's name.
+	 */
+	private String name;
+
+	/**
+	 * The number of books borrowed by the user.
+	 */
+	private int book;
+
+	/**
+	 * Constructor.
+	 *
+	 * @param name The user's name.
+	 * @param book The number of books borrowed by the user.
+	 */
+	public User(String name, int book) {
+		this.name = name;
+		this.book = book;
+	}
+
+	/**
+	 * Getter of the user's name.
+	 *
+	 * @return The user's name.
+	 */
+	public String getName() {
+		return name;
+	}
+
+	/**
+	 * Getter of the number of books borrowed by the user.
+	 *
+	 * @return The number of books borrowed by the user.
+	 */
+	public int getBook() {
+		return book;
+	}
+
+	/**
+	 * Change the number of books borrowed by the user.
+	 *
+	 * @param book The number of books borrowed by the user.
+	 */
+	protected void setBook(int book) {
+		this.book = book;
+	}
+
+	/**
+	 * Increase the number of books borrowed by the user.
+	 *
+	 * @param book The number of books borrowed by the user.
+	 */
+	public abstract void moreBook(int number) throws NotALenderException;
+
+	/**
+	 * Test.
+	 */
+	public static void testUser() {
+		// abstract class not testing
+	}
+}

finalproject/Question10/View.java

@@ -0,0 +1,18 @@
+import javax.swing.JFrame;
+
+public abstract class View<T extends Controller> extends JFrame implements ModelListener {
+	protected Library m;
+	protected T c;
+
+	public View(Library m, T c) {
+		this.m = m;
+		this.c = c;
+
+		m.addListener(this);
+
+		this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
+		this.setLocationRelativeTo(null);
+	}
+
+	public abstract void update();
+}

finalproject/Question10/ViewGetBook.java

@@ -0,0 +1,40 @@
+import java.awt.GridLayout;
+import java.awt.event.ActionEvent;
+import java.awt.event.ActionListener;
+import javax.swing.JButton;
+import javax.swing.JOptionPane;
+import javax.swing.JTextField;
+
+public class ViewGetBook extends View<ControllerGetBook> {
+	private JTextField t;
+
+	public ViewGetBook(Library m, ControllerGetBook c) {
+		super(m, c);
+
+		// win
+		this.setTitle("View GetBook");
+		this.setSize(300, 200);
+
+		GridLayout layout = new GridLayout(2, 1);
+		this.setLayout(layout);
+
+		t = new JTextField();
+		add(t);
+
+		JButton b = new JButton("Tell me the book number");
+		b.addActionListener(new ActionListener() {
+			public void actionPerformed(ActionEvent e) {
+				String result = c.getBook(t.getText());
+				JOptionPane.showMessageDialog(null, result);
+			}
+		});
+		add(b);
+
+		// final
+		this.setVisible(true);
+	}
+
+	public void update() {
+		// do nothing
+	}
+}

finalproject/Question10/ViewMoreBook.java

@@ -0,0 +1,52 @@
+import java.awt.GridLayout;
+import java.awt.event.ActionEvent;
+import java.awt.event.ActionListener;
+import javax.swing.JButton;
+import javax.swing.JOptionPane;
+import javax.swing.JTextField;
+
+public class ViewMoreBook extends View<ControllerMoreBook> {
+	private JTextField tName;
+	private JTextField tBook;
+
+	public ViewMoreBook(Library m, ControllerMoreBook c) {
+		super(m, c);
+
+		// window
+		this.setTitle("View More Book");
+		this.setSize(300, 200);
+
+		GridLayout layout = new GridLayout(3, 1);
+		this.setLayout(layout);
+
+		// text field 1
+		tName = new JTextField();
+		add(tName);
+
+		// text field 2
+		tBook = new JTextField();
+		add(tBook);
+
+		// button
+		JButton b = new JButton("Tell me the book number");
+		b.addActionListener(new ActionListener() {
+			public void actionPerformed(ActionEvent e) {
+				String name = tName.getText();
+				String num = tBook.getText();
+				String result = c.moreBook(name, num);
+
+				// check
+				if (result != "") {
+					JOptionPane.showMessageDialog(null, result);
+				}
+			}
+		});
+		add(b);
+
+		// final
+		this.setVisible(true);
+	}
+
+	public void update() {
+	}
+}

finalproject/Question10/ViewSimple.java

@@ -0,0 +1,29 @@
+/*
+ * Author: CHEN Yongyuan (Walter) 1930006025 from OOP(1007)
+ * Date: 2022-04-25
+ */
+
+import javax.swing.JLabel;
+
+public class ViewSimple extends View<ControllerSimple> {
+	private JLabel label;
+
+	public ViewSimple(Library m, ControllerSimple c) {
+		super(m, c);
+
+		// window
+		this.setTitle("View Simple");
+		this.setSize(300, 200);
+
+		// conponent
+		label = new JLabel("Total number of borrowed books: " + m.totalBorrowedBooks());
+		add(label);
+
+		// final
+		this.setVisible(true);
+	}
+
+	public void update() {
+		label.setText("Total number of borrowed books: " + m.totalBorrowedBooks());
+	}
+}

finalproject/Question11/Borrower.java

@@ -0,0 +1,63 @@
+/*
+ * Author: CHEN Yongyuan (Walter) 1930006025 from OOP(1007)
+ * Date: 2022-04-25
+ * Description: This is the borrower class.
+ */
+
+public class Borrower extends User {
+	/**
+	 * Constructor.
+	 *
+	 * @param name Borrower's name
+	 * @param int  book number of books borrowed by user
+	 */
+	public Borrower(String name, int book) throws NotALenderException {
+		super(name, book);
+
+		// check
+		if (book < 0) {
+			throw new NotALenderException("A new borrower cannot lend books.");
+		}
+	}
+
+	/**
+	 * increase the number of books borrowed by the user.
+	 *
+	 * @param number Incrased number of books
+	 * @throws NotALenderException
+	 */
+	public void moreBook(int number) throws NotALenderException {
+		int newBook = getBook() + number;
+		if (number < 0 && newBook < 0) {
+			throw new NotALenderException("A borrower cannot lend " + (-newBook) + " book(s).");
+		}
+		setBook(newBook);
+	}
+
+	/**
+	 * Test.
+	 */
+	public static void testBorrower() {
+		try {
+			Borrower b = new Borrower("Bob", -1);
+		} catch (NotALenderException e) {
+			System.out.println(e.getMessage().equals("A new borrower cannot lend books."));
+		}
+		try {
+			Borrower b = new Borrower("Bob", 10);
+			System.out.println(b.getName() == "Bob");
+			System.out.println(b.getBook() == 10);
+			b.setBook(5);
+			System.out.println(b.getBook() == 5);
+			b.moreBook(2);
+			System.out.println(b.getBook() == 7);
+			b.moreBook(-2);
+			System.out.println(b.getBook() == 5);
+			b.moreBook(-5);
+			System.out.println(b.getBook() == 0);
+			b.moreBook(-1);
+		} catch (NotALenderException e) {
+			System.out.println(e.getMessage().equals("A borrower cannot lend 1 book(s)."));
+		}
+	}
+}

finalproject/Question11/CLI.java

@@ -0,0 +1,145 @@
+/*
+ * Author: CHEN Yongyuan (Walter) 1930006025 from OOP(1007)
+ * Date: 2022-04-25
+ * Description: This is the CLI class.
+ */
+
+import java.util.InputMismatchException;
+import java.util.Scanner;
+
+public class CLI {
+	private static Scanner input = new Scanner(System.in);
+
+	/**
+	 * Read one line from CLI.
+	 *
+	 * @param message Hint printed to screen
+	 * @return one line input
+	 */
+	private static String readLine(String message) {
+		System.out.print(message);
+		return input.nextLine();
+	}
+
+	/**
+	 * Read one positive integer.
+	 *
+	 * @param message HINT printed to screen
+	 * @return one positive integer
+	 */
+	private static int readPosInt(String message) {
+		while (true) {
+			System.out.print(message);
+			try {
+				int result = input.nextInt();
+				input.nextLine();
+				if (result >= 0) {
+					return result;
+				} else {
+					System.out.println("Positive integers only!");
+				}
+			} catch (InputMismatchException e) {
+				System.out.println("You must type an integer!");
+				input.nextLine();
+			}
+		}
+	}
+
+	public static void main(String[] args) {
+		int book;
+		String username;
+		String menuHint = "Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): ";
+		String userRoleHint = "Type the user role (lender:1 borrower:2): ";
+
+		Library library = new Library("UIC Library");
+		while (true) {
+			switch (readPosInt(menuHint)) {
+				// total
+				case 1:
+					System.out.println("Total number of borrowed books: "
+							+ library.totalBorrowedBooks());
+					break;
+				// add
+				case 2:
+					switch (readPosInt(userRoleHint)) {
+						// lender
+						case 1:
+							username = readLine("Enter the name of the user: ");
+							book = readPosInt(
+									"Enter the initial number of borrowed books: ");
+							Lender lender = new Lender(username, book);
+							library.addUser(lender);
+							System.out.println("Lender \"" + username + "\" lending " + book
+									+ " book(s) has been added.");
+							break;
+						// borrower
+						case 2:
+							username = readLine(
+									"Enter the name of the user: ");
+							book = readPosInt(
+									"Enter the initial number of borrowed books: ");
+							try {
+								library.addUser(new Borrower(username, book));
+								System.out.println("Borrower \""
+										+ username
+										+ "\" borrowing "
+										+ book
+										+ " book(s) has been added.");
+							} catch (NotALenderException e) {
+								System.out.println("BUG! This must never happen!");
+								System.exit(1);
+							}
+							break;
+						default:
+							System.out.println("Unknown user role!");
+							break;
+					}
+					break;
+				// get
+				case 3:
+					username = readLine("Enter the name of the user: ");
+					try {
+						System.out.println(username + " borrows "
+								+ library.getBook(username) + " book(s).");
+					} catch (UnknownUserException e) {
+						System.out.println("User " + username + " unknown.");
+					}
+					break;
+				case 4:
+					username = readLine("Enter the name of the user: ");
+					book = readPosInt("Enter the number of books: ");
+					try {
+						library.moreBook(username, book);
+					} catch (NotALenderException e) {
+						System.out.println("BUG! This must never happen!");
+					} catch (UnknownUserException e) {
+						System.out.println("User " + username + " unknown.");
+					}
+					break;
+				case 5:
+					username = readLine("Enter the name of the user: ");
+					book = readPosInt("Enter the number of books: ");
+					try {
+						// decrease numbers
+						try {
+							library.moreBook(username, -book);
+						} catch (NotALenderException e) {
+							System.out.println("A borrower cannot lend "
+									+ (-(library.getBook(username) - book))
+									+ " book(s).");
+						}
+					} catch (UnknownUserException e) {
+						System.out.println("User " + username + " unknown.");
+					}
+					break;
+				case 6:
+					System.out.println("Goodbye!");
+					System.exit(0);
+					break;
+				default:
+					System.out.println("Unknown action!");
+					break;
+			}
+		}
+	}
+}

finalproject/Question11/Controller.java

@@ -0,0 +1,7 @@
+public class Controller {
+	protected Library m;
+
+	public Controller(Library m) {
+		this.m = m;
+	}
+}

finalproject/Question11/ControllerCreate.java

@@ -0,0 +1,27 @@
+public class ControllerCreate extends Controller {
+	public ControllerCreate(Library m) {
+		super(m);
+	}
+
+	/**
+	* @param name
+	* @param number
+	* @param type
+	* @return
+	*/
+	public String create(String name, String number, int type) {
+		try {
+			int num = Integer.parseInt(number);
+			if (type == 0) {
+				m.addUser(new Lender(name, num));
+			} else {
+				m.addUser(new Borrower(name, num));
+			}
+			return "";
+		} catch (NotALenderException e) {
+			return e.getMessage();
+		} catch (NumberFormatException e) {
+			return e.getMessage();
+		}
+	}
+}

finalproject/Question11/ControllerGetBook.java

@@ -0,0 +1,15 @@
+public class ControllerGetBook extends Controller {
+	public ControllerGetBook(Library m) {
+		super(m);
+	}
+
+	// get book
+	public String getBook(String name) {
+		try {
+			return Integer.toString(m.getBook(name));
+		} catch (UnknownUserException e) {
+			// return error message
+			return e.getMessage();
+		}
+	}
+}

finalproject/Question11/ControllerMoreBook.java

@@ -0,0 +1,27 @@
+public class ControllerMoreBook extends Controller {
+	// constr
+	public ControllerMoreBook(Library m) {
+		super(m);
+	}
+
+	/**
+	 * @param name the username
+	 * @param number the book number
+	 */
+	public String moreBook(String name, String number) {
+		try {
+			int num = Integer.parseInt(number);
+			m.moreBook(name, num);
+			return "";
+
+		} catch (UnknownUserException e) {
+			return e.getMessage();
+
+		} catch (NotALenderException e) {
+			return e.getMessage();
+
+		} catch (NumberFormatException e) {
+			return e.getMessage();
+		}
+	}
+}

finalproject/Question11/ControllerSimple.java

@@ -0,0 +1,12 @@
+/*
+ * Author: CHEN Yongyuan (Walter) 1930006025 from OOP(1007)
+ * Date: 2022-04-25
+ */
+
+public class ControllerSimple extends Controller {
+	private Library m;
+
+	public ControllerSimple(Library m) {
+		super(m);
+	}
+}

finalproject/Question11/GUI.java

@@ -0,0 +1,21 @@
+public class GUI {
+	public static void main(String[] args) {
+		javax.swing.SwingUtilities.invokeLater(new Runnable() {
+			public void run() {
+				Library li = new Library("UIC Library");
+				ControllerSimple cs = new ControllerSimple(li);
+
+				ViewSimple vs = new ViewSimple(li, cs);
+				ControllerGetBook cgb = new ControllerGetBook(li);
+
+				ViewGetBook vgb = new ViewGetBook(li, cgb);
+				ControllerMoreBook cmb = new ControllerMoreBook(li);
+
+				ViewMoreBook vmb = new ViewMoreBook(li, cmb);
+				ControllerCreate cc = new ControllerCreate(li);
+
+				ViewCreate vc = new ViewCreate(li, cc);
+			}
+		});
+	}
+}

finalproject/Question11/IUser.java

@@ -0,0 +1,13 @@
+/*
+ * Author: CHEN Yongyuan (Walter) 1930006025 from OOP(1007)
+ * Date: 2022-04-25
+ * Description: This is the interface of IUser.
+ */
+
+public interface IUser {
+	public String getName();
+
+	public int getBook();
+
+	public void moreBook(int number) throws NotALenderException;
+}

finalproject/Question11/Lender.java

@@ -0,0 +1,42 @@
+/*
+ * Author: CHEN Yongyuan (Walter) 1930006025 from OOP(1007)
+ * Date: 2022-04-25
+ * Description: This is the Lender class.
+ */
+
+public class Lender extends User {
+	/**
+	 * Constructor.
+	 *
+	 * @param name The user's name.
+	 * @param book number of bookds lent by the user. This will be store in negetive value.
+	 */
+	public Lender(String name, int book) {
+		// lender negetive book value
+		super(name, -book);
+	}
+
+	/**
+	 * Increases the number of bookds.
+	 *
+	 * @param book the number of books.
+	 */
+	public void moreBook(int book) {
+		setBook(getBook() - book);
+	}
+
+	/**
+	 * Test.
+	 */
+	public static void testLender() {
+		Lender l = new Lender("Anna", 5);
+		System.out.println(l.getName() == "Anna");
+		System.out.println(l.getBook() == -5);
+		l.setBook(-6);
+		System.out.println(l.getBook() == -6);
+		l.moreBook(2);
+		System.out.println(l.getBook() == -8);
+		l.moreBook(-9);
+		System.out.println(l.getBook() == 1);
+	}
+}

finalproject/Question11/Library.java

@@ -0,0 +1,122 @@
+/*
+ * Author: CHEN Yongyuan (Walter) 1930006025 from OOP(1007)
+ * Date: 2022-04-25
+ * Description: This is the Library class.
+ */
+
+import java.util.ArrayList;
+
+public class Library {
+	private String name;
+	private ArrayList<IUser> users;
+	private ArrayList<ModelListener> listeners;
+
+	/**
+	 * Constructor.
+	 *
+	 * @param name
+	 */
+	public Library(String name) {
+		this.name = name;
+
+		// init array list
+		this.users = new ArrayList<IUser>();
+		this.listeners = new ArrayList<ModelListener>();
+	}
+
+	// GUI Related
+	public void addListener(ModelListener listener) {
+		listeners.add(listener);
+	}
+
+	// GUI Related
+	private void notifyListeners() {
+		for (ModelListener listener : listeners) {
+			listener.update();
+		}
+	}
+
+	/**
+	 * Add the user to the array list.
+	 *
+	 * @param user The user to be added
+	 */
+	public void addUser(IUser user) {
+		users.add(user);
+		notifyListeners();
+	}
+
+	/**
+	 * The total number of bookds borrowed by all users.
+	 *
+	 * @return the number of books.
+	 */
+	public int totalBorrowedBooks() {
+		int total = 0;
+		for (IUser user : users) {
+			total += user.getBook();
+		}
+		return total;
+	}
+
+	/**
+	 * Get the number of books borrowed by this user.
+	 *
+	 * @param name the name of the query user
+	 * @return the number of books
+	 * @throws UnknownUserException if user not found
+	 */
+	public int getBook(String name) throws UnknownUserException {
+		for (IUser user : users) {
+			if (user.getName().equals(name)) {
+				return user.getBook();
+			}
+		}
+		// user not found
+		throw new UnknownUserException("User " + name + " unknown.");
+	}
+
+	/**
+	 * Change the number of books currently borrowed by that user.
+	 *
+	 * @param name   the user's name
+	 * @param number the number of books
+	 * @throws UnknownUserException user not found
+	 * @throws NotALenderException  can not lend book
+	 */
+	public void moreBook(String name, int number) throws UnknownUserException, NotALenderException {
+		for (IUser user : users) {
+			if (user.getName().equals(name)) {
+				user.moreBook(number);
+				notifyListeners();
+				return;
+			}
+		}
+		// user not found
+		throw new UnknownUserException("User " + name + " unknown.");
+	}
+
+	/**
+	 * Test.
+	 */
+	public static void testLibrary() {
+		Library li = new Library("UIC Library");
+		System.out.println(li.totalBorrowedBooks() == 0);
+		li.addUser(new Lender("L1", 10));
+		try {
+			System.out.println(li.getBook("L1") == -10);
+			System.out.println(li.totalBorrowedBooks() == -10);
+			li.addUser(new Borrower("B1", 20));
+			System.out.println(li.getBook("L1") == -10);
+			System.out.println(li.getBook("B1") == 20);
+			System.out.println(li.totalBorrowedBooks() == 10);
+			li.getBook("B2");
+		} catch (UnknownUserException ex) {
+			System.out.println(ex.getMessage().equals("User B2 unknown."));
+		} catch (NotALenderException ex) {
+			// This should never happen!
+			System.out.println(false);
+		}
+		// More test cases are needed
+	}
+}

finalproject/Question11/ModelListener.java

@@ -0,0 +1,3 @@
+public interface ModelListener {
+	public void update();
+}

finalproject/Question11/NotALenderException.java

@@ -0,0 +1,5 @@
+public class NotALenderException extends Exception {
+	public NotALenderException(String message) {
+		super(message);
+	}
+}

finalproject/Question11/Test.java

@@ -0,0 +1,8 @@
+public class Test {
+	public static void main(String[] args) {
+		User.testUser();
+		Lender.testLender();
+		Borrower.testBorrower();
+		Library.testLibrary();
+	}
+}

finalproject/Question11/UnknownUserException.java

@@ -0,0 +1,5 @@
+public class UnknownUserException extends Exception {
+	public UnknownUserException(String message) {
+		super(message);
+	}
+}

finalproject/Question11/User.java

@@ -0,0 +1,69 @@
+/*
+ * Author: CHEN Yongyuan (Walter) 1930006025 from OOP(1007)
+ * Date: 2022-04-25
+ * Description: This is the User class.
+ */
+
+public abstract class User implements IUser {
+	/**
+	 * The user's name.
+	 */
+	private String name;
+
+	/**
+	 * The number of books borrowed by the user.
+	 */
+	private int book;
+
+	/**
+	 * Constructor.
+	 *
+	 * @param name The user's name.
+	 * @param book The number of books borrowed by the user.
+	 */
+	public User(String name, int book) {
+		this.name = name;
+		this.book = book;
+	}
+
+	/**
+	 * Getter of the user's name.
+	 *
+	 * @return The user's name.
+	 */
+	public String getName() {
+		return name;
+	}
+
+	/**
+	 * Getter of the number of books borrowed by the user.
+	 *
+	 * @return The number of books borrowed by the user.
+	 */
+	public int getBook() {
+		return book;
+	}
+
+	/**
+	 * Change the number of books borrowed by the user.
+	 *
+	 * @param book The number of books borrowed by the user.
+	 */
+	protected void setBook(int book) {
+		this.book = book;
+	}
+
+	/**
+	 * Increase the number of books borrowed by the user.
+	 *
+	 * @param book The number of books borrowed by the user.
+	 */
+	public abstract void moreBook(int number) throws NotALenderException;
+
+	/**
+	 * Test.
+	 */
+	public static void testUser() {
+		// abstract class not testing
+	}
+}

finalproject/Question11/View.java

@@ -0,0 +1,18 @@
+import javax.swing.JFrame;
+
+public abstract class View<T extends Controller> extends JFrame implements ModelListener {
+	protected Library m;
+	protected T c;
+
+	public View(Library m, T c) {
+		this.m = m;
+		this.c = c;
+
+		m.addListener(this);
+
+		this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
+		this.setLocationRelativeTo(null);
+	}
+
+	public abstract void update();
+}

finalproject/Question11/ViewCreate.java

@@ -0,0 +1,60 @@
+import java.awt.GridLayout;
+import java.awt.event.ActionEvent;
+import java.awt.event.ActionListener;
+import javax.swing.JButton;
+import javax.swing.JComboBox;
+import javax.swing.JOptionPane;
+import javax.swing.JTextField;
+
+public class ViewCreate extends View<ControllerCreate> {
+	private JTextField tName;
+	private JTextField tBook;
+	private JComboBox<String> cb;
+
+	public ViewCreate(Library m, ControllerCreate c) {
+		super(m, c);
+
+		// window
+		this.setTitle("View Create");
+		this.setSize(300, 200);
+
+		GridLayout layout = new GridLayout(4, 1);
+		this.setLayout(layout);
+
+		// text field
+		tName = new JTextField();
+		add(tName);
+
+		// text field
+		tBook = new JTextField();
+		add(tBook);
+
+		// box
+		cb = new JComboBox<String>();
+		cb.addItem("Lender");
+		cb.addItem("Borrower");
+		add(cb);
+
+		// button
+		JButton b = new JButton("Create");
+		b.addActionListener(new ActionListener() {
+			public void actionPerformed(ActionEvent e) {
+				String name = tName.getText();
+				String num = tBook.getText();
+				String result = c.create(name, num, cb.getSelectedIndex());
+
+				// check
+				if (result != "") {
+					JOptionPane.showMessageDialog(null, result);
+				}
+			}
+		});
+		add(b);
+
+		// final
+		this.setVisible(true);
+	}
+
+	public void update() {
+	}
+}

finalproject/Question11/ViewGetBook.java

@@ -0,0 +1,40 @@
+import java.awt.GridLayout;
+import java.awt.event.ActionEvent;
+import java.awt.event.ActionListener;
+import javax.swing.JButton;
+import javax.swing.JOptionPane;
+import javax.swing.JTextField;
+
+public class ViewGetBook extends View<ControllerGetBook> {
+	private JTextField t;
+
+	public ViewGetBook(Library m, ControllerGetBook c) {
+		super(m, c);
+
+		// win
+		this.setTitle("View GetBook");
+		this.setSize(300, 200);
+
+		GridLayout layout = new GridLayout(2, 1);
+		this.setLayout(layout);
+
+		t = new JTextField();
+		add(t);
+
+		JButton b = new JButton("Tell me the book number");
+		b.addActionListener(new ActionListener() {
+			public void actionPerformed(ActionEvent e) {
+				String result = c.getBook(t.getText());
+				JOptionPane.showMessageDialog(null, result);
+			}
+		});
+		add(b);
+
+		// final
+		this.setVisible(true);
+	}
+
+	public void update() {
+		// do nothing
+	}
+}

finalproject/Question11/ViewMoreBook.java

@@ -0,0 +1,52 @@
+import java.awt.GridLayout;
+import java.awt.event.ActionEvent;
+import java.awt.event.ActionListener;
+import javax.swing.JButton;
+import javax.swing.JOptionPane;
+import javax.swing.JTextField;
+
+public class ViewMoreBook extends View<ControllerMoreBook> {
+	private JTextField tName;
+	private JTextField tBook;
+
+	public ViewMoreBook(Library m, ControllerMoreBook c) {
+		super(m, c);
+
+		// window
+		this.setTitle("View More Book");
+		this.setSize(300, 200);
+
+		GridLayout layout = new GridLayout(3, 1);
+		this.setLayout(layout);
+
+		// text field 1
+		tName = new JTextField();
+		add(tName);
+
+		// text field 2
+		tBook = new JTextField();
+		add(tBook);
+
+		// button
+		JButton b = new JButton("Tell me the book number");
+		b.addActionListener(new ActionListener() {
+			public void actionPerformed(ActionEvent e) {
+				String name = tName.getText();
+				String num = tBook.getText();
+				String result = c.moreBook(name, num);
+
+				// check
+				if (result != "") {
+					JOptionPane.showMessageDialog(null, result);
+				}
+			}
+		});
+		add(b);
+
+		// final
+		this.setVisible(true);
+	}
+
+	public void update() {
+	}
+}

finalproject/Question11/ViewSimple.java

@@ -0,0 +1,29 @@
+/*
+ * Author: CHEN Yongyuan (Walter) 1930006025 from OOP(1007)
+ * Date: 2022-04-25
+ */
+
+import javax.swing.JLabel;
+
+public class ViewSimple extends View<ControllerSimple> {
+	private JLabel label;
+
+	public ViewSimple(Library m, ControllerSimple c) {
+		super(m, c);
+
+		// window
+		this.setTitle("View Simple");
+		this.setSize(300, 200);
+
+		// conponent
+		label = new JLabel("Total number of borrowed books: " + m.totalBorrowedBooks());
+		add(label);
+
+		// final
+		this.setVisible(true);
+	}
+
+	public void update() {
+		label.setText("Total number of borrowed books: " + m.totalBorrowedBooks());
+	}
+}

finalproject/Question12/Borrower.java

@@ -0,0 +1,63 @@
+/*
+ * Author: CHEN Yongyuan (Walter) 1930006025 from OOP(1007)
+ * Date: 2022-04-25
+ * Description: This is the borrower class.
+ */
+
+public class Borrower extends User {
+	/**
+	 * Constructor.
+	 *
+	 * @param name Borrower's name
+	 * @param int  book number of books borrowed by user
+	 */
+	public Borrower(String name, int book) throws NotALenderException {
+		super(name, book);
+
+		// check
+		if (book < 0) {
+			throw new NotALenderException("A new borrower cannot lend books.");
+		}
+	}
+
+	/**
+	 * increase the number of books borrowed by the user.
+	 *
+	 * @param number Incrased number of books
+	 * @throws NotALenderException
+	 */
+	public void moreBook(int number) throws NotALenderException {
+		int newBook = getBook() + number;
+		if (number < 0 && newBook < 0) {
+			throw new NotALenderException("A borrower cannot lend " + (-newBook) + " book(s).");
+		}
+		setBook(newBook);
+	}
+
+	/**
+	 * Test.
+	 */
+	public static void testBorrower() {
+		try {
+			Borrower b = new Borrower("Bob", -1);
+		} catch (NotALenderException e) {
+			System.out.println(e.getMessage().equals("A new borrower cannot lend books."));
+		}
+		try {
+			Borrower b = new Borrower("Bob", 10);
+			System.out.println(b.getName() == "Bob");
+			System.out.println(b.getBook() == 10);
+			b.setBook(5);
+			System.out.println(b.getBook() == 5);
+			b.moreBook(2);
+			System.out.println(b.getBook() == 7);
+			b.moreBook(-2);
+			System.out.println(b.getBook() == 5);
+			b.moreBook(-5);
+			System.out.println(b.getBook() == 0);
+			b.moreBook(-1);
+		} catch (NotALenderException e) {
+			System.out.println(e.getMessage().equals("A borrower cannot lend 1 book(s)."));
+		}
+	}
+}

finalproject/Question12/CLI.java

@@ -0,0 +1,145 @@
+/*
+ * Author: CHEN Yongyuan (Walter) 1930006025 from OOP(1007)
+ * Date: 2022-04-25
+ * Description: This is the CLI class.
+ */
+
+import java.util.InputMismatchException;
+import java.util.Scanner;
+
+public class CLI {
+	private static Scanner input = new Scanner(System.in);
+
+	/**
+	 * Read one line from CLI.
+	 *
+	 * @param message Hint printed to screen
+	 * @return one line input
+	 */
+	private static String readLine(String message) {
+		System.out.print(message);
+		return input.nextLine();
+	}
+
+	/**
+	 * Read one positive integer.
+	 *
+	 * @param message HINT printed to screen
+	 * @return one positive integer
+	 */
+	private static int readPosInt(String message) {
+		while (true) {
+			System.out.print(message);
+			try {
+				int result = input.nextInt();
+				input.nextLine();
+				if (result >= 0) {
+					return result;
+				} else {
+					System.out.println("Positive integers only!");
+				}
+			} catch (InputMismatchException e) {
+				System.out.println("You must type an integer!");
+				input.nextLine();
+			}
+		}
+	}
+
+	public static void main(String[] args) {
+		int book;
+		String username;
+		String menuHint = "Type an action (total:1 add:2 get:3 more:4 less:5 quit:6): ";
+		String userRoleHint = "Type the user role (lender:1 borrower:2): ";
+
+		Library library = new Library("UIC Library");
+		while (true) {
+			switch (readPosInt(menuHint)) {
+				// total
+				case 1:
+					System.out.println("Total number of borrowed books: "
+							+ library.totalBorrowedBooks());
+					break;
+				// add
+				case 2:
+					switch (readPosInt(userRoleHint)) {
+						// lender
+						case 1:
+							username = readLine("Enter the name of the user: ");
+							book = readPosInt(
+									"Enter the initial number of borrowed books: ");
+							Lender lender = new Lender(username, book);
+							library.addUser(lender);
+							System.out.println("Lender \"" + username + "\" lending " + book
+									+ " book(s) has been added.");
+							break;
+						// borrower
+						case 2:
+							username = readLine(
+									"Enter the name of the user: ");
+							book = readPosInt(
+									"Enter the initial number of borrowed books: ");
+							try {
+								library.addUser(new Borrower(username, book));
+								System.out.println("Borrower \""
+										+ username
+										+ "\" borrowing "
+										+ book
+										+ " book(s) has been added.");
+							} catch (NotALenderException e) {
+								System.out.println("BUG! This must never happen!");
+								System.exit(1);
+							}
+							break;
+						default:
+							System.out.println("Unknown user role!");
+							break;
+					}
+					break;
+				// get
+				case 3:
+					username = readLine("Enter the name of the user: ");
+					try {
+						System.out.println(username + " borrows "
+								+ library.getBook(username) + " book(s).");
+					} catch (UnknownUserException e) {
+						System.out.println("User " + username + " unknown.");
+					}
+					break;
+				case 4:
+					username = readLine("Enter the name of the user: ");
+					book = readPosInt("Enter the number of books: ");
+					try {
+						library.moreBook(username, book);
+					} catch (NotALenderException e) {
+						System.out.println("BUG! This must never happen!");
+					} catch (UnknownUserException e) {
+						System.out.println("User " + username + " unknown.");
+					}
+					break;
+				case 5:
+					username = readLine("Enter the name of the user: ");
+					book = readPosInt("Enter the number of books: ");
+					try {
+						// decrease numbers
+						try {
+							library.moreBook(username, -book);
+						} catch (NotALenderException e) {
+							System.out.println("A borrower cannot lend "
+									+ (-(library.getBook(username) - book))
+									+ " book(s).");
+						}
+					} catch (UnknownUserException e) {
+						System.out.println("User " + username + " unknown.");
+					}
+					break;
+				case 6:
+					System.out.println("Goodbye!");
+					System.exit(0);
+					break;
+				default:
+					System.out.println("Unknown action!");
+					break;
+			}
+		}
+	}
+}

finalproject/Question12/Controller.java

@@ -0,0 +1,7 @@
+public class Controller {
+	protected Library m;
+
+	public Controller(Library m) {
+		this.m = m;
+	}
+}

finalproject/Question12/ControllerCreate.java

@@ -0,0 +1,27 @@
+public class ControllerCreate extends Controller {
+	public ControllerCreate(Library m) {
+		super(m);
+	}
+
+	/**
+	* @param name
+	* @param number
+	* @param type
+	* @return
+	*/
+	public String create(String name, String number, int type) {
+		try {
+			int num = Integer.parseInt(number);
+			if (type == 0) {
+				m.addUser(new Lender(name, num));
+			} else {
+				m.addUser(new Borrower(name, num));
+			}
+			return "";
+		} catch (NotALenderException e) {
+			return e.getMessage();
+		} catch (NumberFormatException e) {
+			return e.getMessage();
+		}
+	}
+}

finalproject/Question12/ControllerGetBook.java

@@ -0,0 +1,15 @@
+public class ControllerGetBook extends Controller {
+	public ControllerGetBook(Library m) {
+		super(m);
+	}
+
+	// get book
+	public String getBook(String name) {
+		try {
+			return Integer.toString(m.getBook(name));
+		} catch (UnknownUserException e) {
+			// return error message
+			return e.getMessage();
+		}
+	}
+}

finalproject/Question12/ControllerMoreBook.java

@@ -0,0 +1,27 @@
+public class ControllerMoreBook extends Controller {
+	// constr
+	public ControllerMoreBook(Library m) {
+		super(m);
+	}
+
+	/**
+	 * @param name the username
+	 * @param number the book number
+	 */
+	public String moreBook(String name, String number) {
+		try {
+			int num = Integer.parseInt(number);
+			m.moreBook(name, num);
+			return "";
+
+		} catch (UnknownUserException e) {
+			return e.getMessage();
+
+		} catch (NotALenderException e) {
+			return e.getMessage();
+
+		} catch (NumberFormatException e) {
+			return e.getMessage();
+		}
+	}
+}

finalproject/Question12/ControllerSimple.java

@@ -0,0 +1,12 @@
+/*
+ * Author: CHEN Yongyuan (Walter) 1930006025 from OOP(1007)
+ * Date: 2022-04-25
+ */
+
+public class ControllerSimple extends Controller {
+	private Library m;
+
+	public ControllerSimple(Library m) {
+		super(m);
+	}
+}

finalproject/Question12/GUI.java

@@ -0,0 +1,21 @@
+public class GUI {
+	public static void main(String[] args) {
+		javax.swing.SwingUtilities.invokeLater(new Runnable() {
+			public void run() {
+				Library li = new Library("UIC Library");
+				ControllerSimple cs = new ControllerSimple(li);
+
+				ViewSimple vs = new ViewSimple(li, cs);
+				ControllerGetBook cgb = new ControllerGetBook(li);
+
+				ViewGetBook vgb = new ViewGetBook(li, cgb);
+				ControllerMoreBook cmb = new ControllerMoreBook(li);
+
+				ViewMoreBook vmb = new ViewMoreBook(li, cmb);
+				ControllerCreate cc = new ControllerCreate(li);
+
+				ViewCreate vc = new ViewCreate(li, cc);
+			}
+		});
+	}
+}

finalproject/Question12/IUser.java

@@ -0,0 +1,13 @@
+/*
+ * Author: CHEN Yongyuan (Walter) 1930006025 from OOP(1007)
+ * Date: 2022-04-25
+ * Description: This is the interface of IUser.
+ */
+
+public interface IUser {
+	public String getName();
+
+	public int getBook();
+
+	public void moreBook(int number) throws NotALenderException;
+}

finalproject/Question12/I_GIVE_UP.LOG

@@ -0,0 +1 @@
+giveup

finalproject/Question12/Lender.java

@@ -0,0 +1,42 @@
+/*
+ * Author: CHEN Yongyuan (Walter) 1930006025 from OOP(1007)
+ * Date: 2022-04-25
+ * Description: This is the Lender class.
+ */
+
+public class Lender extends User {
+	/**
+	 * Constructor.
+	 *
+	 * @param name The user's name.
+	 * @param book number of bookds lent by the user. This will be store in negetive value.
+	 */
+	public Lender(String name, int book) {
+		// lender negetive book value
+		super(name, -book);
+	}
+
+	/**
+	 * Increases the number of bookds.
+	 *
+	 * @param book the number of books.
+	 */
+	public void moreBook(int book) {
+		setBook(getBook() - book);
+	}
+
+	/**
+	 * Test.
+	 */
+	public static void testLender() {
+		Lender l = new Lender("Anna", 5);
+		System.out.println(l.getName() == "Anna");
+		System.out.println(l.getBook() == -5);
+		l.setBook(-6);
+		System.out.println(l.getBook() == -6);
+		l.moreBook(2);
+		System.out.println(l.getBook() == -8);
+		l.moreBook(-9);
+		System.out.println(l.getBook() == 1);
+	}
+}

finalproject/Question12/Library.java

@@ -0,0 +1,122 @@
+/*
+ * Author: CHEN Yongyuan (Walter) 1930006025 from OOP(1007)
+ * Date: 2022-04-25
+ * Description: This is the Library class.
+ */
+
+import java.util.ArrayList;
+
+public class Library {
+	private String name;
+	private ArrayList<IUser> users;
+	private ArrayList<ModelListener> listeners;
+
+	/**
+	 * Constructor.
+	 *
+	 * @param name
+	 */
+	public Library(String name) {
+		this.name = name;
+
+		// init array list
+		this.users = new ArrayList<IUser>();
+		this.listeners = new ArrayList<ModelListener>();
+	}
+
+	// GUI Related
+	public void addListener(ModelListener listener) {
+		listeners.add(listener);
+	}
+
+	// GUI Related
+	private void notifyListeners() {
+		for (ModelListener listener : listeners) {
+			listener.update();
+		}
+	}
+
+	/**
+	 * Add the user to the array list.
+	 *
+	 * @param user The user to be added
+	 */
+	public void addUser(IUser user) {
+		users.add(user);
+		notifyListeners();
+	}
+
+	/**
+	 * The total number of bookds borrowed by all users.
+	 *
+	 * @return the number of books.
+	 */
+	public int totalBorrowedBooks() {
+		int total = 0;
+		for (IUser user : users) {
+			total += user.getBook();
+		}
+		return total;
+	}
+
+	/**
+	 * Get the number of books borrowed by this user.
+	 *
+	 * @param name the name of the query user
+	 * @return the number of books
+	 * @throws UnknownUserException if user not found
+	 */
+	public int getBook(String name) throws UnknownUserException {
+		for (IUser user : users) {
+			if (user.getName().equals(name)) {
+				return user.getBook();
+			}
+		}
+		// user not found
+		throw new UnknownUserException("User " + name + " unknown.");
+	}
+
+	/**
+	 * Change the number of books currently borrowed by that user.
+	 *
+	 * @param name   the user's name
+	 * @param number the number of books
+	 * @throws UnknownUserException user not found
+	 * @throws NotALenderException  can not lend book
+	 */
+	public void moreBook(String name, int number) throws UnknownUserException, NotALenderException {
+		for (IUser user : users) {
+			if (user.getName().equals(name)) {
+				user.moreBook(number);
+				notifyListeners();
+				return;
+			}
+		}
+		// user not found
+		throw new UnknownUserException("User " + name + " unknown.");
+	}
+
+	/**
+	 * Test.
+	 */
+	public static void testLibrary() {
+		Library li = new Library("UIC Library");
+		System.out.println(li.totalBorrowedBooks() == 0);
+		li.addUser(new Lender("L1", 10));
+		try {
+			System.out.println(li.getBook("L1") == -10);
+			System.out.println(li.totalBorrowedBooks() == -10);
+			li.addUser(new Borrower("B1", 20));
+			System.out.println(li.getBook("L1") == -10);
+			System.out.println(li.getBook("B1") == 20);
+			System.out.println(li.totalBorrowedBooks() == 10);
+			li.getBook("B2");
+		} catch (UnknownUserException ex) {
+			System.out.println(ex.getMessage().equals("User B2 unknown."));
+		} catch (NotALenderException ex) {
+			// This should never happen!
+			System.out.println(false);
+		}
+		// More test cases are needed
+	}
+}

finalproject/Question12/ModelListener.java

@@ -0,0 +1,3 @@
+public interface ModelListener {
+	public void update();
+}

finalproject/Question12/NotALenderException.java

@@ -0,0 +1,5 @@
+public class NotALenderException extends Exception {
+	public NotALenderException(String message) {
+		super(message);
+	}
+}

finalproject/Question12/Test.java

@@ -0,0 +1,8 @@
+public class Test {
+	public static void main(String[] args) {
+		User.testUser();
+		Lender.testLender();
+		Borrower.testBorrower();
+		Library.testLibrary();
+	}
+}

finalproject/Question12/UnknownUserException.java

@@ -0,0 +1,5 @@
+public class UnknownUserException extends Exception {
+	public UnknownUserException(String message) {
+		super(message);
+	}
+}

finalproject/Question12/User.java

@@ -0,0 +1,69 @@
+/*
+ * Author: CHEN Yongyuan (Walter) 1930006025 from OOP(1007)
+ * Date: 2022-04-25
+ * Description: This is the User class.
+ */
+
+public abstract class User implements IUser {
+	/**
+	 * The user's name.
+	 */
+	private String name;
+
+	/**
+	 * The number of books borrowed by the user.
+	 */
+	private int book;
+
+	/**
+	 * Constructor.
+	 *
+	 * @param name The user's name.
+	 * @param book The number of books borrowed by the user.
+	 */
+	public User(String name, int book) {
+		this.name = name;
+		this.book = book;
+	}
+
+	/**
+	 * Getter of the user's name.
+	 *
+	 * @return The user's name.
+	 */
+	public String getName() {
+		return name;
+	}
+
+	/**
+	 * Getter of the number of books borrowed by the user.
+	 *
+	 * @return The number of books borrowed by the user.
+	 */
+	public int getBook() {
+		return book;
+	}
+
+	/**
+	 * Change the number of books borrowed by the user.
+	 *
+	 * @param book The number of books borrowed by the user.
+	 */
+	protected void setBook(int book) {
+		this.book = book;
+	}
+
+	/**
+	 * Increase the number of books borrowed by the user.
+	 *
+	 * @param book The number of books borrowed by the user.
+	 */
+	public abstract void moreBook(int number) throws NotALenderException;
+
+	/**
+	 * Test.
+	 */
+	public static void testUser() {
+		// abstract class not testing
+	}
+}

finalproject/Question12/View.java

@@ -0,0 +1,18 @@
+import javax.swing.JFrame;
+
+public abstract class View<T extends Controller> extends JFrame implements ModelListener {
+	protected Library m;
+	protected T c;
+
+	public View(Library m, T c) {
+		this.m = m;
+		this.c = c;
+
+		m.addListener(this);
+
+		this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
+		this.setLocationRelativeTo(null);
+	}
+
+	public abstract void update();
+}

finalproject/Question12/ViewCreate.java

@@ -0,0 +1,60 @@
+import java.awt.GridLayout;
+import java.awt.event.ActionEvent;
+import java.awt.event.ActionListener;
+import javax.swing.JButton;
+import javax.swing.JComboBox;
+import javax.swing.JOptionPane;
+import javax.swing.JTextField;
+
+public class ViewCreate extends View<ControllerCreate> {
+	private JTextField tName;
+	private JTextField tBook;
+	private JComboBox<String> cb;
+
+	public ViewCreate(Library m, ControllerCreate c) {
+		super(m, c);
+
+		// window
+		this.setTitle("View Create");
+		this.setSize(300, 200);
+
+		GridLayout layout = new GridLayout(4, 1);
+		this.setLayout(layout);
+
+		// text field
+		tName = new JTextField();
+		add(tName);
+
+		// text field
+		tBook = new JTextField();
+		add(tBook);
+
+		// box
+		cb = new JComboBox<String>();
+		cb.addItem("Lender");
+		cb.addItem("Borrower");
+		add(cb);
+
+		// button
+		JButton b = new JButton("Create");
+		b.addActionListener(new ActionListener() {
+			public void actionPerformed(ActionEvent e) {
+				String name = tName.getText();
+				String num = tBook.getText();
+				String result = c.create(name, num, cb.getSelectedIndex());
+
+				// check
+				if (result != "") {
+					JOptionPane.showMessageDialog(null, result);
+				}
+			}
+		});
+		add(b);
+
+		// final
+		this.setVisible(true);
+	}
+
+	public void update() {
+	}
+}

finalproject/Question12/ViewGetBook.java

@@ -0,0 +1,40 @@
+import java.awt.GridLayout;
+import java.awt.event.ActionEvent;
+import java.awt.event.ActionListener;
+import javax.swing.JButton;
+import javax.swing.JOptionPane;
+import javax.swing.JTextField;
+
+public class ViewGetBook extends View<ControllerGetBook> {
+	private JTextField t;
+
+	public ViewGetBook(Library m, ControllerGetBook c) {
+		super(m, c);
+
+		// win
+		this.setTitle("View GetBook");
+		this.setSize(300, 200);
+
+		GridLayout layout = new GridLayout(2, 1);
+		this.setLayout(layout);
+
+		t = new JTextField();
+		add(t);
+
+		JButton b = new JButton("Tell me the book number");
+		b.addActionListener(new ActionListener() {
+			public void actionPerformed(ActionEvent e) {
+				String result = c.getBook(t.getText());
+				JOptionPane.showMessageDialog(null, result);
+			}
+		});
+		add(b);
+
+		// final
+		this.setVisible(true);
+	}
+
+	public void update() {
+		// do nothing
+	}
+}

finalproject/Question12/ViewMoreBook.java

@@ -0,0 +1,52 @@
+import java.awt.GridLayout;
+import java.awt.event.ActionEvent;
+import java.awt.event.ActionListener;
+import javax.swing.JButton;
+import javax.swing.JOptionPane;
+import javax.swing.JTextField;
+
+public class ViewMoreBook extends View<ControllerMoreBook> {
+	private JTextField tName;
+	private JTextField tBook;
+
+	public ViewMoreBook(Library m, ControllerMoreBook c) {
+		super(m, c);
+
+		// window
+		this.setTitle("View More Book");
+		this.setSize(300, 200);
+
+		GridLayout layout = new GridLayout(3, 1);
+		this.setLayout(layout);
+
+		// text field 1
+		tName = new JTextField();
+		add(tName);
+
+		// text field 2
+		tBook = new JTextField();
+		add(tBook);
+
+		// button
+		JButton b = new JButton("Tell me the book number");
+		b.addActionListener(new ActionListener() {
+			public void actionPerformed(ActionEvent e) {
+				String name = tName.getText();
+				String num = tBook.getText();
+				String result = c.moreBook(name, num);
+
+				// check
+				if (result != "") {
+					JOptionPane.showMessageDialog(null, result);
+				}
+			}
+		});
+		add(b);
+
+		// final
+		this.setVisible(true);
+	}
+
+	public void update() {
+	}
+}

finalproject/Question12/ViewSimple.java

@@ -0,0 +1,29 @@
+/*
+ * Author: CHEN Yongyuan (Walter) 1930006025 from OOP(1007)
+ * Date: 2022-04-25
+ */
+
+import javax.swing.JLabel;
+
+public class ViewSimple extends View<ControllerSimple> {
+	private JLabel label;
+
+	public ViewSimple(Library m, ControllerSimple c) {
+		super(m, c);
+
+		// window
+		this.setTitle("View Simple");
+		this.setSize(300, 200);
+
+		// conponent
+		label = new JLabel("Total number of borrowed books: " + m.totalBorrowedBooks());
+		add(label);
+
+		// final
+		this.setVisible(true);
+	}
+
+	public void update() {
+		label.setText("Total number of borrowed books: " + m.totalBorrowedBooks());
+	}
+}

finalproject/Question2/IUser.java

@@ -0,0 +1,13 @@
+/*
+ * Author: CHEN Yongyuan (Walter) 1930006025 from OOP(1007)
+ * Date: 2022-04-25
+ * Description: This is the interface of IUser.
+ */
+
+public interface IUser {
+	public String getName();
+
+	public int getBook();
+
+	public void moreBook(int number);
+}

finalproject/Question2/Lender.java

@@ -0,0 +1,42 @@
+/*
+ * Author: CHEN Yongyuan (Walter) 1930006025 from OOP(1007)
+ * Date: 2022-04-25
+ * Description: This is the Lender class.
+ */
+
+public class Lender extends User {
+	/**
+	 * Constructor.
+	 *
+	 * @param name The user's name.
+	 * @param book number of bookds lent by the user. This will be store in negetive value.
+	 */
+	public Lender(String name, int book) {
+		// lender negetive book value
+		super(name, -book);
+	}
+
+	/**
+	 * Increases the number of bookds.
+	 *
+	 * @param book the number of books.
+	 */
+	public void moreBook(int book) {
+		setBook(getBook() - book);
+	}
+
+	/**
+	 * Test.
+	 */
+	public static void testLender() {
+		Lender l = new Lender("Anna", 5);
+		System.out.println(l.getName() == "Anna");
+		System.out.println(l.getBook() == -5);
+		l.setBook(-6);
+		System.out.println(l.getBook() == -6);
+		l.moreBook(2);
+		System.out.println(l.getBook() == -8);
+		l.moreBook(-9);
+		System.out.println(l.getBook() == 1);
+	}
+}

finalproject/Question2/Test.java

@@ -0,0 +1,6 @@
+public class Test {
+	public static void main(String[] args) {
+		User.testUser();
+		Lender.testLender();
+	}
+}

finalproject/Question2/User.java

@@ -0,0 +1,78 @@
+/*
+ * Author: CHEN Yongyuan (Walter) 1930006025 from OOP(1007)
+ * Date: 2022-04-25
+ * Description: This is the User class.
+ */
+
+public abstract class User implements IUser {
+	/**
+	 * The user's name.
+	 */
+	private String name;
+
+	/**
+	 * The number of books borrowed by the user.
+	 */
+	private int book;
+
+	/**
+	 * Constructor.
+	 *
+	 * @param name The user's name.
+	 * @param book The number of books borrowed by the user.
+	 */
+	public User(String name, int book) {
+		this.name = name;
+		this.book = book;
+	}
+
+	/**
+	 * Getter of the user's name.
+	 *
+	 * @return The user's name.
+	 */
+	public String getName() {
+		return name;
+	}
+
+	/**
+	 * Getter of the number of books borrowed by the user.
+	 *
+	 * @return The number of books borrowed by the user.
+	 */
+	public int getBook() {
+		return book;
+	}
+
+	/**
+	 * Change the number of books borrowed by the user.
+	 *
+	 * @param book The number of books borrowed by the user.
+	 */
+	protected void setBook(int book) {
+		this.book = book;
+	}
+
+	/**
+	 * Increase the number of books borrowed by the user.
+	 *
+	 * @param book The number of books borrowed by the user.
+	 */
+	public abstract void moreBook(int number);
+
+	/**
+	 * Test.
+	 */
+	public static void testUser() {
+		User user = new User("Walter", 3) {
+			@Override
+			public void moreBook(int number) {
+				setBook(getBook() + number);
+			}
+		};
+		System.out.println(user.getName() == "Walter");
+		System.out.println(user.getBook() == 3);
+		user.moreBook(2);
+		System.out.println(user.getBook() == 5);
+	}
+}

finalproject/Question3/Borrower.java

@@ -0,0 +1,63 @@
+/*
+ * Author: CHEN Yongyuan (Walter) 1930006025 from OOP(1007)
+ * Date: 2022-04-25
+ * Description: This is the borrower class.
+ */
+
+public class Borrower extends User {
+	/**
+	 * Constructor.
+	 *
+	 * @param name Borrower's name
+	 * @param int  book number of books borrowed by user
+	 */
+	public Borrower(String name, int book) throws NotALenderException {
+		super(name, book);
+
+		// check
+		if (book < 0) {
+			throw new NotALenderException("A new borrower cannot lend books.");
+		}
+	}
+
+	/**
+	 * increase the number of books borrowed by the user.
+	 *
+	 * @param number Incrased number of books
+	 * @throws NotALenderException
+	 */
+	public void moreBook(int number) throws NotALenderException {
+		int newBook = getBook() + number;
+		if (number < 0 && newBook < 0) {
+			throw new NotALenderException("A borrower cannot lend " + (-newBook) + " book(s).");
+		}
+		setBook(newBook);
+	}
+
+	/**
+	 * Test.
+	 */
+	public static void testBorrower() {
+		try {
+			Borrower b = new Borrower("Bob", -1);
+		} catch (NotALenderException e) {
+			System.out.println(e.getMessage().equals("A new borrower cannot lend books."));
+		}
+		try {
+			Borrower b = new Borrower("Bob", 10);
+			System.out.println(b.getName() == "Bob");
+			System.out.println(b.getBook() == 10);
+			b.setBook(5);
+			System.out.println(b.getBook() == 5);
+			b.moreBook(2);
+			System.out.println(b.getBook() == 7);
+			b.moreBook(-2);
+			System.out.println(b.getBook() == 5);
+			b.moreBook(-5);
+			System.out.println(b.getBook() == 0);
+			b.moreBook(-1);
+		} catch (NotALenderException e) {
+			System.out.println(e.getMessage().equals("A borrower cannot lend 1 book(s)."));
+		}
+	}
+}

finalproject/Question3/IUser.java

@@ -0,0 +1,13 @@
+/*
+ * Author: CHEN Yongyuan (Walter) 1930006025 from OOP(1007)
+ * Date: 2022-04-25
+ * Description: This is the interface of IUser.
+ */
+
+public interface IUser {
+	public String getName();
+
+	public int getBook();
+
+	public void moreBook(int number) throws NotALenderException;
+}

finalproject/Question3/Lender.java

@@ -0,0 +1,42 @@
+/*
+ * Author: CHEN Yongyuan (Walter) 1930006025 from OOP(1007)
+ * Date: 2022-04-25
+ * Description: This is the Lender class.
+ */
+
+public class Lender extends User {
+	/**
+	 * Constructor.
+	 *
+	 * @param name The user's name.
+	 * @param book number of bookds lent by the user. This will be store in negetive value.
+	 */
+	public Lender(String name, int book) {
+		// lender negetive book value
+		super(name, -book);
+	}
+
+	/**
+	 * Increases the number of bookds.
+	 *
+	 * @param book the number of books.
+	 */
+	public void moreBook(int book) {
+		setBook(getBook() - book);
+	}
+
+	/**
+	 * Test.
+	 */
+	public static void testLender() {
+		Lender l = new Lender("Anna", 5);
+		System.out.println(l.getName() == "Anna");
+		System.out.println(l.getBook() == -5);
+		l.setBook(-6);
+		System.out.println(l.getBook() == -6);
+		l.moreBook(2);
+		System.out.println(l.getBook() == -8);
+		l.moreBook(-9);
+		System.out.println(l.getBook() == 1);
+	}
+}

finalproject/Question3/NotALenderException.java

@@ -0,0 +1,5 @@
+public class NotALenderException extends Exception {
+	public NotALenderException(String message) {
+		super(message);
+	}
+}

finalproject/Question3/Test.java

@@ -0,0 +1,7 @@
+public class Test {
+	public static void main(String[] args) {
+		User.testUser();
+		Lender.testLender();
+		Borrower.testBorrower();
+	}
+}

finalproject/Question3/User.java

@@ -0,0 +1,69 @@
+/*
+ * Author: CHEN Yongyuan (Walter) 1930006025 from OOP(1007)
+ * Date: 2022-04-25
+ * Description: This is the User class.
+ */
+
+public abstract class User implements IUser {
+	/**
+	 * The user's name.
+	 */
+	private String name;
+
+	/**
+	 * The number of books borrowed by the user.
+	 */
+	private int book;
+
+	/**
+	 * Constructor.
+	 *
+	 * @param name The user's name.
+	 * @param book The number of books borrowed by the user.
+	 */
+	public User(String name, int book) {
+		this.name = name;
+		this.book = book;
+	}
+
+	/**
+	 * Getter of the user's name.
+	 *
+	 * @return The user's name.
+	 */
+	public String getName() {
+		return name;
+	}
+
+	/**
+	 * Getter of the number of books borrowed by the user.
+	 *
+	 * @return The number of books borrowed by the user.
+	 */
+	public int getBook() {
+		return book;
+	}
+
+	/**
+	 * Change the number of books borrowed by the user.
+	 *
+	 * @param book The number of books borrowed by the user.
+	 */
+	protected void setBook(int book) {
+		this.book = book;
+	}
+
+	/**
+	 * Increase the number of books borrowed by the user.
+	 *
+	 * @param book The number of books borrowed by the user.
+	 */
+	public abstract void moreBook(int number) throws NotALenderException;
+
+	/**
+	 * Test.
+	 */
+	public static void testUser() {
+		// abstract class not testing
+	}
+}

finalproject/Question4/Borrower.java

@@ -0,0 +1,63 @@
+/*
+ * Author: CHEN Yongyuan (Walter) 1930006025 from OOP(1007)
+ * Date: 2022-04-25
+ * Description: This is the borrower class.
+ */
+
+public class Borrower extends User {
+	/**
+	 * Constructor.
+	 *
+	 * @param name Borrower's name
+	 * @param int  book number of books borrowed by user
+	 */
+	public Borrower(String name, int book) throws NotALenderException {
+		super(name, book);
+
+		// check
+		if (book < 0) {
+			throw new NotALenderException("A new borrower cannot lend books.");
+		}
+	}
+
+	/**
+	 * increase the number of books borrowed by the user.
+	 *
+	 * @param number Incrased number of books
+	 * @throws NotALenderException
+	 */
+	public void moreBook(int number) throws NotALenderException {
+		int newBook = getBook() + number;
+		if (number < 0 && newBook < 0) {
+			throw new NotALenderException("A borrower cannot lend " + (-newBook) + " book(s).");
+		}
+		setBook(newBook);
+	}
+
+	/**
+	 * Test.
+	 */
+	public static void testBorrower() {
+		try {
+			Borrower b = new Borrower("Bob", -1);
+		} catch (NotALenderException e) {
+			System.out.println(e.getMessage().equals("A new borrower cannot lend books."));
+		}
+		try {
+			Borrower b = new Borrower("Bob", 10);
+			System.out.println(b.getName() == "Bob");
+			System.out.println(b.getBook() == 10);
+			b.setBook(5);
+			System.out.println(b.getBook() == 5);
+			b.moreBook(2);
+			System.out.println(b.getBook() == 7);
+			b.moreBook(-2);
+			System.out.println(b.getBook() == 5);
+			b.moreBook(-5);
+			System.out.println(b.getBook() == 0);
+			b.moreBook(-1);
+		} catch (NotALenderException e) {
+			System.out.println(e.getMessage().equals("A borrower cannot lend 1 book(s)."));
+		}
+	}
+}

finalproject/Question4/IUser.java

@@ -0,0 +1,13 @@
+/*
+ * Author: CHEN Yongyuan (Walter) 1930006025 from OOP(1007)
+ * Date: 2022-04-25
+ * Description: This is the interface of IUser.
+ */
+
+public interface IUser {
+	public String getName();
+
+	public int getBook();
+
+	public void moreBook(int number) throws NotALenderException;
+}

finalproject/Question4/Lender.java

@@ -0,0 +1,42 @@
+/*
+ * Author: CHEN Yongyuan (Walter) 1930006025 from OOP(1007)
+ * Date: 2022-04-25
+ * Description: This is the Lender class.
+ */
+
+public class Lender extends User {
+	/**
+	 * Constructor.
+	 *
+	 * @param name The user's name.
+	 * @param book number of bookds lent by the user. This will be store in negetive value.
+	 */
+	public Lender(String name, int book) {
+		// lender negetive book value
+		super(name, -book);
+	}
+
+	/**
+	 * Increases the number of bookds.
+	 *
+	 * @param book the number of books.
+	 */
+	public void moreBook(int book) {
+		setBook(getBook() - book);
+	}
+
+	/**
+	 * Test.
+	 */
+	public static void testLender() {
+		Lender l = new Lender("Anna", 5);
+		System.out.println(l.getName() == "Anna");
+		System.out.println(l.getBook() == -5);
+		l.setBook(-6);
+		System.out.println(l.getBook() == -6);
+		l.moreBook(2);
+		System.out.println(l.getBook() == -8);
+		l.moreBook(-9);
+		System.out.println(l.getBook() == 1);
+	}
+}

finalproject/Question4/Library.java

@@ -0,0 +1,100 @@
+import java.util.ArrayList;
+
+public class Library {
+	private String name;
+	private ArrayList<IUser> users;
+
+	/**
+	 * Constructor.
+	 *
+	 * @param name
+	 */
+	public Library(String name) {
+		this.name = name;
+
+		// init array list
+		users = new ArrayList<IUser>();
+	}
+
+	/**
+	 * Add the user to the array list.
+	 *
+	 * @param user The user to be added
+	 */
+	public void addUser(IUser user) {
+		users.add(user);
+	}
+
+	/**
+	 * The total number of bookds borrowed by all users.
+	 *
+	 * @return the number of books.
+	 */
+	public int totalBorrowedBooks() {
+		int total = 0;
+		for (IUser user : users) {
+			total += user.getBook();
+		}
+		return total;
+	}
+
+	/**
+	 * Get the number of books borrowed by this user.
+	 *
+	 * @param name the name of the query user
+	 * @return the number of books
+	 * @throws UnknownUserException if user not found
+	 */
+	public int getBook(String name) throws UnknownUserException {
+		for (IUser user : users) {
+			if (user.getName().equals(name)) {
+				return user.getBook();
+			}
+		}
+		// user not found
+		throw new UnknownUserException("User " + name + " unknown.");
+	}
+
+	/**
+	 * Change the number of books currently borrowed by that user.
+	 *
+	 * @param name   the user's name
+	 * @param number the number of books
+	 * @throws UnknownUserException user not found
+	 * @throws NotALenderException  can not lend book
+	 */
+	public void moreBook(String name, int number) throws UnknownUserException, NotALenderException {
+		for (IUser user : users) {
+			if (user.getName().equals(name)) {
+				user.moreBook(number);
+				return;
+			}
+		}
+		// user not found
+		throw new UnknownUserException("User " + name + " unknown.");
+	}
+
+	/**
+	 * Test.
+	 */
+	public static void testLibrary() {
+		Library li = new Library("UIC Library");
+		System.out.println(li.totalBorrowedBooks() == 0);
+		li.addUser(new Lender("L1", 10));
+		try {
+			System.out.println(li.getBook("L1") == -10);
+			System.out.println(li.totalBorrowedBooks() == -10);
+			li.addUser(new Borrower("B1", 20));
+			System.out.println(li.getBook("L1") == -10);
+			System.out.println(li.getBook("B1") == 20);
+			System.out.println(li.totalBorrowedBooks() == 10);
+			li.getBook("B2");
+		} catch (UnknownUserException ex) {
+			System.out.println(ex.getMessage().equals("User B2 unknown."));
+		} catch (NotALenderException ex) {
+			// This should never happen!
+			System.out.println(false);
+		}
+		// More test cases are needed
+	}
+}

finalproject/Question4/NotALenderException.java

@@ -0,0 +1,5 @@
+public class NotALenderException extends Exception {
+	public NotALenderException(String message) {
+		super(message);
+	}
+}

finalproject/Question4/Test.java

@@ -0,0 +1,8 @@
+public class Test {
+	public static void main(String[] args) {
+		User.testUser();
+		Lender.testLender();
+		Borrower.testBorrower();
+		Library.testLibrary();
+	}
+}

finalproject/Question4/UnknownUserException.java

@@ -0,0 +1,5 @@
+public class UnknownUserException extends Exception {
+	public UnknownUserException(String message) {
+		super(message);
+	}
+}

finalproject/Question4/User.java

@@ -0,0 +1,69 @@
+/*
+ * Author: CHEN Yongyuan (Walter) 1930006025 from OOP(1007)
+ * Date: 2022-04-25
+ * Description: This is the User class.
+ */
+
+public abstract class User implements IUser {
+	/**
+	 * The user's name.
+	 */
+	private String name;
+
+	/**
+	 * The number of books borrowed by the user.
+	 */
+	private int book;
+
+	/**
+	 * Constructor.
+	 *
+	 * @param name The user's name.
+	 * @param book The number of books borrowed by the user.
+	 */
+	public User(String name, int book) {
+		this.name = name;
+		this.book = book;
+	}
+
+	/**
+	 * Getter of the user's name.
+	 *
+	 * @return The user's name.
+	 */
+	public String getName() {
+		return name;
+	}
+
+	/**
+	 * Getter of the number of books borrowed by the user.
+	 *
+	 * @return The number of books borrowed by the user.
+	 */
+	public int getBook() {
+		return book;
+	}
+
+	/**
+	 * Change the number of books borrowed by the user.
+	 *
+	 * @param book The number of books borrowed by the user.
+	 */
+	protected void setBook(int book) {
+		this.book = book;
+	}
+
+	/**
+	 * Increase the number of books borrowed by the user.
+	 *
+	 * @param book The number of books borrowed by the user.
+	 */
+	public abstract void moreBook(int number) throws NotALenderException;
+
+	/**
+	 * Test.
+	 */
+	public static void testUser() {
+		// abstract class not testing
+	}
+}