area of circle in java code example

Example 1: Java program to calculate area of a circle

import java.util.Scanner;
public class CalculateAreaOfCircle
{
   public static void main(String[] args)
   {
      double radius;
      double pi = 3.1415, area;
      Scanner sc = new Scanner(System.in);
      System.out.println("Please enter radius of circle: ");
      radius = sc.nextDouble();
      area = pi * radius * radius;
      System.out.println("Area of circle: " + area);
      sc.close();
   }
}

Example 2: area of circle in java

import java.util.Scanner;
public class AreaOfCircle {
   public static void main(String args[]){
      int radius;
      double area;
      Scanner sc = new Scanner(System.in);
      System.out.println("Enter the radius of the circle ::");
      radius = sc.nextInt();
      area = (radius*radius)*Math.PI;
      System.out.println("Area of the circle is ::"+area);
   }
}

Example 3: how to create a circle in java

public class scratch {
    public static void main(String[] args) {
        JFrame window = new JFrame();
        window.setTitle("Christmas Tree");
        window.setSize(700, 600);
        window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        window.setVisible(true);
        DrawingComponent DC = new DrawingComponent();
        window.add(DC);
    }
}
class DrawingComponent extends JComponent{
      public void paint(Graphics graph0){
        Graphics2D graph = (Graphics2D) graph0;
        Ellipse2D.Double circle = new Ellipse.Double(5, 5, 25, 25);
        graph.fill(circle);
      }
}