Question

Question:

A. Write an Octagon class that inherits from GeometricObject and implements the Comparable interface, comparing the area of the shape. You can assume that all the sides are equal in length.

B. Implement the Comparable interface in the Circle and Rectangle from Question2 comparing the area of each shape. (use the same classes in Question 2)

C. Also add the overloaded toString() method to each class that prints a summary of the object. Then, in another class, create an ArrayList of at least one of each Circle , Rectangle and Octagon .

D. Write 2 methods: i. A sumArea() method that takes an ArrayList of GeometricObjects and returns the sum for the entire list

ii. A printSorted() method that takes an ArrayList, sorts it by area (using the compareTo() method) and then prints the sorted list using the overloaded toString() method.

Thank you so much!

Answer 1

Java Code:

GeometricObject.java

package main;

//GeometricObject Class
public class GeometricObject implements Comparable<GeometricObject> {
   protected double length; //variables
   protected double width;
   protected double area;
  

   @Override
   public int compareTo(GeometricObject arg0) {//Compare to method
      
       return (int) (this.area-arg0.area) ; //comparing areas
   }
  
}

Octagon.java

package main;
//Octagon Class
public class Octagon extends GeometricObject {
  
   Octagon(double length){ //constructor
       this.area = (1+Math.sqrt(2))*2*length;
       this.length = length;
   }
  
  
   @Override
   public String toString() { //toString Method
       return "Area of Octagon of side length " + this.length + " is " + this.area;
   }
}

Circle.java

package main;
//Circle Class
public class Circle extends GeometricObject {
  
   Circle(double radius){ //constructor
       this.area = Math.PI*2*radius;
       this.length = radius;
   }
  
   @Override
   public String toString() { //toString Method
      
       return "Area of Circle of radius " + this.length + " is " + this.area;
   }
  
}

Rectangle.java

package main;
//Rectangle Class
public class Rectangle extends GeometricObject {
  
   Rectangle(double length, double width){ //constructor
       this.area = length * width;
       this.length = length;
       this.width = width;
   }
  
   @Override
   public String toString() { //toString Method
      
       return "Area of Rectangle with dimensions " + this.length+ " x " + this.width + " is " + this.area;
   }
}

Main.java

package main;
//imports
import java.util.*;
//Main Class
public class Main {
//main method
   public static void main(String[] args) {
       //creating objects of GeometricObject
       GeometricObject circle = new Circle(4);
       GeometricObject rectangle = new Rectangle(4, 7);
       GeometricObject octagon = new Octagon(4);
      
       //Creating array list to store objects
       List<GeometricObject> geoObj = new ArrayList<GeometricObject>();
       geoObj.add(circle);
       geoObj.add(rectangle);
       geoObj.add(octagon);
      
       System.out.println("Sum of the area is: " + sumArea(geoObj)); //printing sum
       printSorted(geoObj); //printing sorted array
   }
  
   static double sumArea(List<GeometricObject> geoObj) {
       double sum=0;
      
       for(GeometricObject geo : geoObj) {
           sum+=geo.area; //iterating and calculating sum
       }
       return sum;
   }
  
   static void printSorted(List<GeometricObject> geoObj) {
      
       System.out.println();
       //printing list before sorting
       System.out.println("Before sorting the List is:");
       for(GeometricObject geo : geoObj) {
           System.out.println(geo.toString());
       }
      
       System.out.println();
      
       Collections.sort(geoObj); //sorting array list
      
       System.out.println("Sorted List is:"); //printing list after sorting
       for(GeometricObject geo : geoObj) {
           System.out.println(geo.toString());
       }
   }

}

Sample Output:

Sum of the area is: 72.44644972770311

Before sorting the List is:
Area of Circle of radius 4.0 is 25.132741228718345
Area of Rectangle with dimensions 4.0 x 7.0 is 28.0
Area of Octagon of side length 4.0 is 19.31370849898476

Sorted List is:
Area of Octagon of side length 4.0 is 19.31370849898476
Area of Circle of radius 4.0 is 25.132741228718345
Area of Rectangle with dimensions 4.0 x 7.0 is 28.0