SWING - JPanel Class


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Introduction

The class JPanel is a generic lightweight container.

Class Declaration

Following is the declaration for javax.swing.JPanel class −

public class JPanel
   extends JComponent
      implements Accessible

Class Constructors

Sr.No. Constructor & Description
1

JPanel()

Creates a new JPanel with a double buffer and a flow layout.

2

JPanel(boolean isDoubleBuffered)

Creates a new JPanel with FlowLayout and the specified buffering strategy.

3

JPanel(LayoutManager layout)

Creates a new buffered JPanel with the specified layout manager.

4

JPanel(LayoutManager layout, boolean isDoubleBuffered)

Creates a new JPanel with the specified layout manager and buffering strategy.

Class Methods

Sr.No. Method & Description
1

AccessibleContext getAccessibleContext()

Gets the AccessibleContext associated with this JPanel.

2

PanelUI getUI()

Returns the look and feel (L&F) object that renders this component.

3

String getUIClassID()

Returns a string that specifies the name of the L&F class which renders this component.

4

protected String paramString()

Returns a string representation of this JPanel.

5

void setUI(PanelUI ui)

Sets the look and feel (L&F) object that renders this component.

6

void updateUI()

Resets the UI property with a value from the current look and feel.

Methods Inherited

This class inherits methods from the following classes −

  • javax.swing.JComponent
  • java.awt.Container
  • java.awt.Component
  • java.lang.Object

JPanel Example

Create the following Java program using any editor of your choice in say D:/ > SWING > com > tutorialspoint > gui >

SwingContainerDemo.java

package com.tutorialspoint.gui;

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

public class SwingContainerDemo {
   private JFrame mainFrame;
   private JLabel headerLabel;
   private JLabel statusLabel;
   private JPanel controlPanel;
   private JLabel msglabel;

   public SwingContainerDemo(){
      prepareGUI();
   }
   public static void main(String[] args){
      SwingContainerDemo  swingContainerDemo = new SwingContainerDemo();  
      swingContainerDemo.showJPanelDemo();
   }
   private void prepareGUI(){
      mainFrame = new JFrame("Java Swing Examples");
      mainFrame.setSize(400,400);
      mainFrame.setLayout(new GridLayout(3, 1));
      
      mainFrame.addWindowListener(new WindowAdapter() {
         public void windowClosing(WindowEvent windowEvent){
            System.exit(0);
         }        
      });    
      headerLabel = new JLabel("", JLabel.CENTER);        
      statusLabel = new JLabel("",JLabel.CENTER);    
      statusLabel.setSize(350,100);
      msglabel = new JLabel("Welcome to TutorialsPoint SWING Tutorial.", JLabel.CENTER);
      controlPanel = new JPanel();
      controlPanel.setLayout(new FlowLayout());

      mainFrame.add(headerLabel);
      mainFrame.add(controlPanel);
      mainFrame.add(statusLabel);
      mainFrame.setVisible(true);  
   }
   private void showJPanelDemo(){
      headerLabel.setText("Container in action: JPanel");      
      JPanel panel = new JPanel();
      panel.setBackground(Color.magenta);
      panel.setLayout(new FlowLayout());        
      panel.add(msglabel);
      controlPanel.add(panel);        
      mainFrame.setVisible(true);      
   }   
}

Compile the program using the command prompt. Go to D:/ > SWING and type the following command.

D:\SWING>javac com\tutorialspoint\gui\SwingContainerDemo.java

If no error occurs, it means the compilation is successful. Run the program using the following command.

D:\SWING>java com.tutorialspoint.gui.SwingContainerDemo

Verify the following output.

SWING JPanel
swing_containers.htm

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