JFrame ContentPane Layout in Java Swing Example

In a Java Swing, A JFrame is the class that represents the window in which graphics applications running on Java. JFrame Class is the top-level container that contains content pane all visible components contain in the content pane. The usual procedure to be used to create a new class that inherits from JFrame. Normally JFrame’s are used as primary containers, that is, not contained in other containers.

A frame is often put a main panel from which the other elements are organized. To place this main panel method is used.
public void setContentPane(Cantainer contentPane)

import java.awt.*; 
 import javax.swing.*; 
 public class JFrameContentPane  extends JFrame 
 {    
      private final int SIZE = 200; 
      private Container con = getContentPane(); 
      private JButton BtnClckIt = new JButton("Click it"); 
      public JFrameContentPane() 
        { 
           super("JFrame ContentPane Layout in Java Swing Example"); 
           setSize(500,500); 
           setVisible(true); 
           con.setLayout(new FlowLayout()); 
           con.add(BtnClckIt); 
        } 
          public static void main(String[] args) 
           { 
             JFrameContentPane JFrameCP = new JFrameContentPane(); 
           }         
   }