Question

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1)

2)

Point3D Class Write a class named Point3D that extends the generic Point class you wrote in Tuesday's lab. The Point3D class is generic but restricted to Number and its subclasses. The Point3D class has a z field that contains the z coordinate. Provide a constructor for the Point3D class. Provide an accessor and mutator for field Z. Demonstrate in a main method. PointList Class Write a class named PointList that keeps a list of Point objects in an ArrayList. The PointList class should accept any object that is an instance of the Point class, or a subclass of Point, or a subclass of Point. Demonstrate the class in an application.

Answer 1

/*
    Please find the required solution
 */


// Point class with x, y

import java.util.ArrayList;
import java.util.List;

class Point {
    private int x;
    private int y;

    public Point(int x, int y) {
        this.x = x;
        this.y = y;
    }

    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;
    }

    @Override
    public String toString() {
        return "{" +
                "x=" + x +
                ", y=" + y +
                '}';
    }
}

//Point3D class, subclass of Point with z
class Point3D extends Point {
    private int z;

    public Point3D(int x, int y, int z) {
        super(x, y);
        this.z = z;
    }

    public int getZ() {
        return z;
    }

    public void setZ(int z) {
        this.z = z;
    }

    @Override
    public String toString() {
        return "{" +
                "x=" + this.getX() +
                ", y=" + this.getY() +
                ", z=" + z +
                '}';
    }
}

// PointList class
public class PointList {

    public static void main(String[] args) {

        // define ArrayList point list
        List<Point> pointList = new ArrayList<>();

        // add point to pointList
        pointList.add(new Point(1, 2));

        // add point3D(subclass of Point) to pointList
        pointList.add(new Point3D(1, 2, 3));

        // print PointList
        System.out.println("Point List: " + pointList);

    }
}
Sample output:

[{x=1, y-2 } , {x=1, y-2 , z=3)]