lab8 finished

2022-04-17 11:41:41 +08:00
parent fdb4e8296d
commit cea6585033
43 changed files with 2645 additions and 0 deletions
--- a/lab/lab8/Question8/Circle.java
+++ b/lab/lab8/Question8/Circle.java
@@ -0,0 +1,115 @@
+/*
+ * Author: CHEN Yongyuan (Walter) 1930006025 from OOP(1007)
+ * Date: 2022-04-14
+ * Description: Circle class inherit from Shape class
+ */
+
+public class Circle extends Shape {
+	private double radius;
+
+	/**
+	 * Constructor.
+	 *
+	 * @param x      the x coordinate of the center of the circle
+	 * @param y      the y coordinate of the center of the circle
+	 * @param radius the radius of the circle, must be positive
+	 * @throws BadRadiusException if the radius is negative
+	 */
+	public Circle(double x, double y, double radius) throws BadRadiusException {
+		super(x, y);
+		this.radius = radius;
+
+		if (radius < 0) {
+			throw new BadRadiusException("Radius must be positive!");
+		}
+	}
+
+	/**
+	 * Calculates the area of the circle.
+	 *
+	 * @return the area of the circle
+	 */
+	@Override
+	public double area() {
+		return Math.PI * radius * radius;
+	}
+
+	/**
+	 * Resizing a circle cahnges its radius to be newRadius.
+	 *
+	 * @param newRadius
+	 */
+	@Override
+	public void resize(double newRadius) throws BadRadiusException {
+		if (newRadius < 0) {
+			throw new BadRadiusException("Radius must be positive!");
+		}
+		radius = newRadius;
+	}
+
+	/**
+	 * Test.
+	 */
+	public static void testCircle() {
+		// Create a circle with a positive radius.
+		// No exception is thrown until we resize with a
+		// negative radius.
+		try {
+			Circle c = new Circle(1.2, 3.4, 4.0);
+			// getX, getY, and move are inherited from Shape.
+			// area and resize come from Circle itself.
+			System.out.println(c.getX() == 1.2);
+			System.out.println(c.getY() == 3.4);
+			System.out.println(c.area() == Math.PI * 16.0);
+			// Move the circle. The area does not change.
+			c.move(7.8, 9.0);
+			System.out.println(c.getX() == 9.0);
+			System.out.println(c.getY() == 12.4);
+			System.out.println(c.area() == Math.PI * 16.0);
+			// Resize the circle. The area changes but not the position.
+			c.resize(8.0);
+			System.out.println(c.getX() == 9.0);
+			System.out.println(c.getY() == 12.4);
+			System.out.println(c.area() == Math.PI * 64.0);
+			// Resize the circle with a negative radius.
+			// An exception is thrown, caught, and tested.
+			c.resize(-12.3);
+			System.out.println(c.getX() == 9.0); // Unreachable.
+			System.out.println(c.getY() == 12.4);
+			System.out.println(c.area() == Math.PI * 64.0);
+		} catch (BadRadiusException ex) {
+			System.out.println(ex.getMessage() == "Radius must be positive!");
+		}
+		// Create a circle with a positive radius.
+		// Resize the circle with a zero radius.
+		// No exception is thrown.
+		try {
+			Circle c = new Circle(1.2, 3.4, 4.0);
+			c.resize(0.0);
+			// The area is now zero, the position does not change.
+			System.out.println(c.getX() == 1.2);
+			System.out.println(c.getY() == 3.4);
+			System.out.println(c.area() == 0.0);
+		} catch (BadRadiusException ex) {
+			System.out.println("BUG! This must never happen!");
+		}
+		// Try to create a circle with a negative radius.
+		// An exception is thrown, caught, and tested.
+		try {
+			Circle c2 = new Circle(1.2, 3.4, -5.6);
+		} catch (BadRadiusException ex) {
+			System.out.println(ex.getMessage() == "Radius must be positive!");
+		}
+		// Create a circle with a zero radius.
+		// No exception is thrown.
+		try {
+			Circle c3 = new Circle(1.2, 3.4, 0.0);
+			System.out.println(c3.getX() == 1.2);
+			System.out.println(c3.getY() == 3.4);
+			System.out.println(c3.area() == 0.0);
+		} catch (BadRadiusException ex) {
+			System.out.println("BUG! This must never happen!");
+		}
+
+	}
+}