How to insert a JButton?

Hi,

In chich method do I need to write code to add a JButton ?

Code:

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import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.awt.geom.*;

public class Ex2 extends JApplet {
  public static void main(String s[]) {
    JFrame frame = new JFrame();
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    JApplet applet = new Ex2();
    applet.init();
    frame.getContentPane().add(applet);
    frame.pack();
    frame.setVisible(true);
  }
 
  public void init() {
    JPanel panel = new Ex2Panel();
    getContentPane().add(panel);
  }
}

class Ex2Panel extends JPanel{         
  public Ex2Panel() {
    setPreferredSize(new Dimension(400, 400));
    setBackground(Color.white);
  }

  public void paintComponent(Graphics g) {
    super.paintComponent(g);
    Graphics2D g2 = (Graphics2D)g;
    int w = this.getWidth();
    int h = this.getHeight();
    int r = Math.min(w, h) - 100;
    Area a = new Area(new Rectangle(r, r));
    a.subtract(new Area(new Ellipse2D.Double(r/4, r/4, r/2, r/2)));
    g2.translate((w-r)/2, (h-r)/2);
    g2.setColor(Color.green);
    g2.fill(a);
    g2.setColor(Color.black);
    g2.draw(a);
  }
}

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please explain what this code does and what you want to do. do you want the button to show up in both the applet and the application? or just one of them?