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by Dinesh Thakur

This example is used to calculate the area and circumference of a circle with given radius. The class Circle contains the field radius and methods setData (), area ()and circumference ().The statement.

Circle obj = new Circle();

creates a Circle object in memory and assign it to the reference variable obj,

The statement,

obj.setData(3.5) ;

assigns the radius field of the Circle object to 3.5 using the reference variable obj.

The statement,

obj.area ();

obj.circumference() ;

calculates the area and circumference of the corresponding Circle object, which is finally displayed.

class circle

{
     double radius; //radius of circle
     void setData(double r)
     {
        radius = r;
     }
     void area ()
     {
        double circleArea = Math.PI * radius *radius;
        System.out.println("Area of circle is = " + circleArea);
     }
     void circumference()
     {
        double cir = 2 * Math.PI * radius ;
        System.out.println("circumference of circle is = " + cir);
     }
     
  }
  public class AreaAndCircumference
{
     public static void main(String[] args)
     {
      
        circle obj = new circle();
        obj.setData(3.5 );  //call setData method
        obj.area( );  //call area method
        obj.circumference( );  //call circumference method
     }
}

Area and Circumference of Circle