JPanel in Java with Example Using NetBeans

JPanel in Java:

The javax class.swing.JPanel is the default container for all controls. It is often used to group related controls. A JPanel usually forms the basis for graphics programming. Depending on the intended use, either further containers are added or, in the case of rather smaller applications, the control elements are placed directly on them. A JPanel is not limited to a certain number of elements it can hold.

JPanel Constructor:

First, let’s look at two constructors that are important:

In the example below we add a JPanel to the dialog. We change the background color of this JPane l so that this panel is also visible. Without a different background color, it would match the background color of the dialog and no difference would be discernible.

Example: How to create a window using JPanel in java:

package com.mycompany.guiexamples;
import  java.awt.Color ; 
import  javax.swing.JDialog ; 
import  javax.swing.JPanel ;


/**
 *
 * @author Fawadkhan
 */
public class Jpanel {
    
    public  static  void main ( String[ ] args ) 
    { 
        // creating object
       JDialog Dialog =  new  JDialog( ) ; 
        Dialog.setTitle ("Testing JPanel") ; 
        Dialog.setSize ( 400 , 300 ) ;
 
        JPanel panel =  new  JPanel( ) ; 
        //Here we set the background color of our JPanel to green 
        panel.setBackground(Color.green) ;
        Dialog.add( panel); // Here we add our JPanel to our dialog  
        Dialog.setVisible( true ); // We display our dialog
    } 

    
} 

In the above example, we create a JPanel object using the default constructor. Then we set the background color of our JPanel to green. 

If you run the above Java source code, you will get the following picture:

Programming explanation:

First I import the required java classes using the import statement

import  java.awt.Color ;

import  javax.swing.JDialog ;

import  javax.swing.JPanel ;

then I create the object for the JDialog and set the title and size of the dialog box

JDialog Dialog =  new  JDialog( ) ;

Dialog.setTitle ("Testing JPanel") ;

Dialog.setSize ( 400 , 300 ) ;

then I create the object for the JPanel

JPanel panel =  new  JPanel( ) ;

Here I set the background color of our JPanel to green

panel.setBackground(Color.green) ;

then I added our JPanel to our dialog

Dialog.add( panel);

This statement is used to display the dialog box

Dialog.setVisible( true );