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assignment1/Question1/AutoRobot.java

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+/*
+ * Authro: CHEN Yongyuan (Walter) 1930006025 from OOP(1007)
+ * Date: 2022/03/09
+ * Description: This is the main class of AutoRobot.
+ */
+
+public class AutoRobot {
+    /**
+     * current speed of the robot.
+     */
+    private double currentSpeed;
+
+    /**
+     * name of the robot
+     */
+    private String name;
+
+    /**
+     * Constructor for objects of class AutoRobot. Default name is "xyz".
+     * Initial speed is 0.
+     */
+    public AutoRobot() {
+        // initialise instance variables
+        this.currentSpeed = 0;
+        this.name = "xyz";
+    }
+
+    /**
+     * Getter method for name.
+     *
+     * @return name of the robot.
+     */
+    public String getName() {
+        return this.name;
+    }
+
+    /**
+     * Getter method for current speed.
+     *
+     * @return current speed of the robot.
+     */
+    public double getCurrentSpeed() {
+        return this.currentSpeed;
+    }
+
+    /**
+     * Increase the speed of the robot by 5. The speed exceed 20 will
+     * print "Dangerous" message and do nothing.
+     *
+     * @return current speed of the robot.
+     */
+    public void accelerate() {
+        if (this.currentSpeed >= 20) {
+            System.out.println("Dangerous! Please stay within speed limit.");
+            return;
+        }
+
+        this.currentSpeed += 5;
+    }
+
+    /**
+     * Decrase the speed of the robot by 5. The speed can not be less than 0.
+     *
+     * @return current speed of the robot.
+     */
+    public void brake() {
+        if (this.currentSpeed - 5 <= 0) {
+            this.currentSpeed = 0;
+            return;
+        }
+
+        this.currentSpeed -= 5;
+    }
+
+    /**
+     * Print out current status.
+     *
+     * @return void.
+     */
+    public void printStatus() {
+        System.out.println(String.format("Hello there, my name is %s and my current speed is %.1f",
+                this.name, this.currentSpeed));
+    }
+
+    /**
+     * Setter method for name.
+     *
+     * @param name name of the robot.
+     * @return void.
+     */
+    public void setName(String name) {
+        this.name = name;
+    }
+    
+    /**
+     * Static test the class AutoRobot.
+     *
+     * @return void.
+     */
+    public static void testAutoRobot() {
+        AutoRobot robot = new AutoRobot();
+
+        // print current status
+        robot.printStatus();
+
+        // print true for default value
+        System.out.println(robot.getName().equals("xyz"));
+        System.out.println(doubleEquals(robot.getCurrentSpeed(), 0));
+        System.out.println(robot.getCurrentSpeed() == 0);
+
+        // change name and print current status
+        robot.setName("ABC");
+
+        // print true for name
+        System.out.println(robot.getName().equals("ABC"));
+
+        // accelerate and print true for current speed
+        robot.accelerate();
+        System.out.println(doubleEquals(robot.getCurrentSpeed(), 5));
+
+        // accelerate and print true for current speed
+        robot.accelerate();
+        System.out.println(doubleEquals(robot.getCurrentSpeed(), 10));
+
+        // brake and print true for current speed
+        robot.brake();
+        System.out.println(doubleEquals(robot.getCurrentSpeed(), 5));
+
+        // accelerate and print true for current speed
+        robot.accelerate();
+        System.out.println(doubleEquals(robot.getCurrentSpeed(), 10));
+
+        // accelerate and print true for current speed
+        robot.accelerate();
+        System.out.println(doubleEquals(robot.getCurrentSpeed(), 15));
+
+        // accelerate and print true for current speed
+        robot.accelerate();
+        System.out.println(doubleEquals(robot.getCurrentSpeed(), 20));
+
+        // accelerate and print true for current speed
+        robot.accelerate();
+        System.out.println(doubleEquals(robot.getCurrentSpeed(), 20));
+
+        // break and print true for current speed
+        robot.brake();
+        System.out.println(doubleEquals(robot.getCurrentSpeed(), 15));
+
+        // brake and print true for current speed
+        robot.brake();
+        System.out.println(doubleEquals(robot.getCurrentSpeed(), 10));
+
+        // brake and print true for current speed
+        robot.brake();
+        System.out.println(doubleEquals(robot.getCurrentSpeed(), 5));
+
+        // brake and print true for current speed
+        robot.brake();
+        System.out.println(doubleEquals(robot.getCurrentSpeed(), 0));
+
+        // brake and print true for current speed
+        robot.brake();
+        System.out.println(doubleEquals(robot.getCurrentSpeed(), 0));
+
+        // print current status
+        robot.printStatus();
+    }
+
+    public static void main(String[] args) {
+        testAutoRobot();
+    }
+
+    /**
+     * Compare double value.
+     *
+     * @param a double value.
+     * @param b double value.
+     * @return true if a and b are equal.
+     */
+    public static boolean doubleEquals(double a, double b) {
+        return Math.abs(a - b) < 0.00001;
+    }
+}