Question

• Define an interface named Shape with a single method named area that calculates the area of the geometric shape:

       public double area();

• Next, define a class named Circle that implements Shape. The Circle class should have an instance variable for the radius, a constructor that sets the radius, an accessor and a mutator method for the radius, and an implementation of the area method.
• Define another class named Rectangle that implements Shape. The Rectangle class should have instance variables for the height and the width, a constructor that sets the height and the width, accessor/mutator methods for the height and the width, and an implementation of the area method.

The following test code should then output the area of the Circle and Rectangle objects:

public static void main (String[] args) {

Circle c = new Circle(4); //Radius=4
Rectangle r = new Rectangle(4, 3); // Height = 4, Width = 3

ShowArea(c);
ShowArea(r);

}

public static void ShowArea(Shape s) {

        double area = s.area();

        System.out.println(“The area of the shape is “ + area);

}

Defining an Inner Class

• Rewrite the given classes Employee, HourlyEmployee, so that the class Date is an inner class of the class Employee and an inherited class of the class HourlyEmployee.
• Write a program to instantiate at least two objects each of type Employee and HourlyEmployee. Display the hire dates for each employee and then modify and display the hire dates for each of the employees.

Answer 1

If you have any queries write a coment if understood upvote Than you.

SOLUTION:

Circle Class:

public class Circle implements Shape {
   //instance variable radius
int radius;
//constructor to set radius
   public Circle(int radius) {
       this.radius=radius;
   }
   //method of shape
   @Override
   public double area() {
       //area of circle is pi*Radius*Radius
       return Math.PI*radius*radius;
   }
  
   public static void main (String[] args) {
//object of circle
       Circle c = new Circle(4); //Radius=4
       //object of rectangle
       Rectangle r = new Rectangle(4, 3); // Height = 4, Width = 3
//call method showArea for displaying the area
       ShowArea(c);
       ShowArea(r);

       }
   //show area method
   public static void ShowArea(Shape s) {
//call the area method
double area = s.area();
System.out.println("The area of the shape is " + area);
}
}

Rectangle Class:

public class Rectangle implements Shape {
int height,width;
   public Rectangle(int height, int width) {
       // TODO Auto-generated constructor stub
       this.height=height;
       this.width=width;
   }
   @Override
   public double area() {
      
       return height*width;
   }

}

Shape interface:

public interface Shape {
   public double area();
}

CODE IMAGE:

Circle class and OUTPUT:

RECTANGLE CLASS :

SHAPE INTERFACE: