Question

Question:

Modify the Rectangle and Box classes that are below, so that they implement the Comparable interface. The compareTo() method shall compare rectangles and boxes by areas and volumes.

In main(), create an ArrayList of rectangles and an ArrayList of boxes. Randomly generate ten rectangles and ten boxes adding to the two ArrayLists. Use Collections.sort() to sort the two ArrayLists, respectively. Print the ArrayLists before and after being sorted.

Three classes that need to be edited are below: Main class, Rectangle class, and Box class.

Main Class:

import java.util.Random;

public class Main{

    public static void main(String[] args){
        // make an array of 100 boxes of random size
        Box[] boxes = new Box[100];
        Random randomNum = new Random();

        int max = 100;
        for (int i = 0; i < 100; i++){
            int l = randomNum.nextInt(max);
            int w = randomNum.nextInt(max);
            int h = randomNum.nextInt(max);
            boxes[i] = new Box(l, w, h);
        }
        int max_volume = 0;
        Box hasMaxVolume = null;

        for (Box box : boxes){
            if (max_volume < box.getVolume()){
                max_volume = box.getVolume();
                hasMaxVolume = box;
            }
        }
        // find the one of biggest volume and print the info of this box
        System.out.println();
        System.out.println("The box with the biggest volume has the volume of: " + hasMaxVolume.getVolume() + "in^3");
        System.out.println();
        hasMaxVolume.print();
        System.out.println();

    }
}

Rectangle class:

public class Rectangle {

    private int l;
    private int w;

    public Rectangle(int l, int w){
        super();
        this.l = l;
        this.w = w;
    }


    public Rectangle(int l){
        super();
        this.l = l;
        this.w = l;
    }

    public Rectangle(){
        super();
    }

    public int getL(){
        return l;
    }

    public void setL(int l){
        this.l = l;
    }

    public int getW(){
        return w;
    }

    public void setW(int w){
        this.w = w;
    }
    // method to calculate area
    public int getArea(){
        return l * w;
    }

    // method to print l and w
    public void print(){
        System.out.print("\"Info of this box is\" " + "Width:" + w + "in" + " Length:" + l + "in");
    }

}

Box class:

public class Box extends Rectangle {

    private int h;
    public Box(int l, int w, int h){
        super(l, w);
        this.h = h;
    }
    public Box(){
        super();
    }
    public Box(int l, int w){
        super(l, w);
    }
    public Box(int l) {
        super(l);
    }
    // method to calculate volume
    public int getVolume() {
        return getArea() * h;
    }
    public int getH() {
        return h;
    }
    public void setH(int h) {
        this.h = h;
    }
    //method to print height
    public void print() {
        super.print();
        System.out.print(" Height:" + h + "in");
    }

}

Answer 1

import java.util.ArrayList;
import java.util.Collections;
import java.util.Random;

public class Main {
    public static void main(String[] args) {
// make an array of 100 boxes of random size
        ArrayList<Box> boxes = new ArrayList<>();
        ArrayList<Rectangle> rectangles = new ArrayList<>();
        
        Random randomNum = new Random();
        int max = 100;
        for (int i = 0; i < 100; i++) {
            int l = randomNum.nextInt(max);
            int w = randomNum.nextInt(max);
            int h = randomNum.nextInt(max);
            boxes.add(new Box(l, w, h));
            
            l = randomNum.nextInt(max);
            w = randomNum.nextInt(max);
            rectangles.add(new Rectangle(l, w));
        }

        System.out.println("Boxes before sorting:");
        for(Box b: boxes) {
            System.out.println(b);
        }
        System.out.println("\nBoxes After sorting:");
        Collections.sort(boxes);        
        for(Box b: boxes) {
            System.out.println(b);
        }

        System.out.println("Rectangles before sorting:");
        for(Rectangle b: rectangles) {
            System.out.println(b);
        }
        System.out.println("\nRectangles After sorting:");
        Collections.sort(boxes);        
        for(Rectangle b: rectangles) {
            System.out.println(b);
        }
    }
}

class Rectangle implements Comparable<Rectangle> {
    private int l;
    private int w;

    public Rectangle(int l, int w) {
        super();
        this.l = l;
        this.w = w;
    }

    public Rectangle(int l) {
        super();
        this.l = l;
        this.w = l;
    }

    public Rectangle() {
        super();
    }

    public int getL() {
        return l;
    }

    public void setL(int l) {
        this.l = l;
    }

    public int getW() {
        return w;
    }

    public void setW(int w) {
        this.w = w;
    }

// method to calculate area
    public int getArea() {
        return l * w;
    }

// method to print l and w
    public String toString() {
        return "\"Info of this box is\" " + "Width:" + w + "in" + " Length:" + l + "in";
    }

    @Override
    public int compareTo(Rectangle o) {
        return getArea() - o.getArea();
    }
}

class Box extends Rectangle {
    private int h;

    public Box(int l, int w, int h) {
        super(l, w);
        this.h = h;
    }

    public Box() {
        super();
    }

    public Box(int l, int w) {
        super(l, w);
    }

    public Box(int l) {
        super(l);
    }

// method to calculate volume
    public int getVolume() {
        return getArea() * h;
    }

    public int getH() {
        return h;
    }

    public void setH(int h) {
        this.h = h;
    }

    public String toString() {
        return super.toString() + " Height:" + h + "in";
    }

    @Override
    public int compareTo(Rectangle o) {
        if (o instanceof Box) {
            return getVolume() - ((Box) o).getVolume();
        }
        return super.compareTo(o);
    }
}

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