Java Program: Design an interface named Colorable with a void method named howTo

Question

Java Program:

Design an interface named Colorable with a void method named howToColor(). Every class of a colorable object must implement the Colorable interface. Design a class named Square that extends GeometricObject and implements Colorable. Implement howToColor to display the message Color all four sides. The Square class has a private double data field named side with its getter and setter methods. It has a no-arg constructor to create a Square with side 1 and another constructor that creates a Square with a specified side.

Write a test program that creates an array of five GeometricObjects. For each object in the array, display its area and invoke its howToColor method if it is colorable.

Explanation / Answer

Colorable.java

public interface Colorable {
   String howToColor();
}

________________

GeometricObject.java

public abstract class GeometricObject {
public abstract double area();
}

__________________

Square.java

public class Square extends GeometricObject implements Colorable {

   double side;
  
   public Square(double side) {
       super();
       this.side = side;
   }

   @Override
   public String howToColor() {
       return "Color All four sides";

   }
public double area()
{
   return side*side;
  
}

}

________________

Rectangle.java

public class Rectangle extends GeometricObject {

   private double length;
   private double width;

   public Rectangle(double length, double width) {
       super();
       this.length = length;
       this.width = width;
   }

   public double area() {
       return length * width;
   }

}

_______________

Circle.java

public class Circle extends GeometricObject {

   private double radius;

   public Circle(double radius) {
       super();
       this.radius = radius;
   }

   public double area() {
       return Math.PI * radius * radius;
   }

}

________________

Test.java

public class Test {

   public static void main(String[] args) {
       GeometricObject[] go={new Square(2), new Circle(5), new Square(5), new Rectangle(3, 4),new Square(4.5)};
      
       for(int i=0;i<go.length;i++)
       {
           System.out.printf(" Area is %.2f ",go[i].area());
           if(go[i] instanceof Colorable)
               System.out.println(((Colorable)go[i]).howToColor()+" ");
       }
      

   }

}

_________________

Output:

Area is 4.00
Color All four sides

Area is 78.54

Area is 25.00
Color All four sides

Area is 12.00

Area is 20.25
Color All four sides

____________Thank You

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