Question

5. [20 marks] (TestRobot.java) Design a class named Robot. The Robot class has three private data fields: position x, position y, and the direction (east, south, west, and north). Assume that positive x points to the east and positive y points to the south, and initially x = 0, y = 0, direction = "east".

Create a no-arg constructor and another constructor which sets the three data fields. Create the accessors and mutators for the three data fields.

Create a method named forward that moves the robot along the current direction for the given distance. For example, if the robot is currently facing east, forward(10) will move the robot along the positive x direction for 10 pixels.

In the main method, create a Robot object, move it to the east for 20 pixels, then set the direction to north and move 30 pixels, and finally set the direction to west and move 40 pixels. Find and display the final x and y values and the direction of robot by calling its methods. For example, for the sample testing above, your program should display x = -20, y = -30, and direction = west.

Answer 1

Program Code [JAVA]

// Robot class

class Robot {

    // Required data fields

    private int position_x;
    private int position_y;
    private String direction;

    // no-arg constructor

    public Robot() {
        this.position_x = 0;
        this.position_y = 0;
        direction = "east";
    }

    // Parameterized constructor

    public Robot(int position_x, int position_y, String direction) {
        this.position_x = position_x;
        this.position_y = position_y;
        this.direction = direction;
    }

    // Accessors & Mutators

    public int getPosition_x() {
        return position_x;
    }

    public void setPosition_x(int position_x) {
        this.position_x = position_x;
    }

    public int getPosition_y() {
        return position_y;
    }

    public void setPosition_y(int position_y) {
        this.position_y = position_y;
    }

    public String getDirection() {
        return direction;
    }

    public void setDirection(String direction) {
        this.direction = direction;
    }

    // forward method

    public void forward(int pixels) {

        // Checking for each direction

        if (direction.equalsIgnoreCase("east"))
            position_x += pixels;
        else if(direction.equalsIgnoreCase("west"))
            position_x -= pixels;
        else if(direction.equalsIgnoreCase("south"))
            position_y += pixels;
        else if(direction.equalsIgnoreCase("north"))
            position_y -= pixels;
    }
}

public class TestRobot {

    // main method

    public static void main(String[] args) {

        // Creating a Robot object

        Robot robot = new Robot();

        // Moving as stated in statement

        robot.setDirection("east");
        robot.forward(20);
        robot.setDirection("north");
        robot.forward(30);
        robot.setDirection("west");
        robot.forward(40);

        // Now printing final values of x, y and direction

        System.out.println("x = " + robot.getPosition_x() + ", y = " + robot.getPosition_y() +
                ", and direction = " + robot.getDirection());
    }
}

Sample Output:-

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