Handle JCheckBox event

In this example we are going to see how to handle JcheckBox events in a Java Desktop Application. Checkboxes are very commonly used when we provide the user with a list of choices and we want him to pick as many as he wishes.

Basically in order to handle JCheckBox events, one should follow these steps:

• Create a class tha extends JFrame and implements ItemListener.
• Create a number of JCheckBoxes.
• Override the itemStateChanged method of ItemListener.
• Use ItemEvent.getItem to get the item which changed state.

 
Let’s take a look at the code snippet that follows:

package com.javacodegeeks.snippets.desktop;

import java.awt.FlowLayout;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;

import javax.swing.JCheckBox;
import javax.swing.JFrame;

public class HandleJCheckBoxEvent extends JFrame implements ItemListener {

	private static final long serialVersionUID = 1L;

	private JCheckBox checkBox1;
	private JCheckBox checkBox2;
	private JCheckBox checkBox3;

	public HandleJCheckBoxEvent() {

		// set flow layout for the frame
		this.getContentPane().setLayout(new FlowLayout());

		checkBox1 = new JCheckBox("Checkbox 1");
		checkBox2 = new JCheckBox("Checkbox 2");
		checkBox3 = new JCheckBox("Checkbox 3");

		checkBox1.addItemListener(this);
		checkBox2.addItemListener(this);
		checkBox3.addItemListener(this);

		// add checkboxes to frame
		add(checkBox1);
		add(checkBox2);
		add(checkBox3);

	}

	@Override
	public void itemStateChanged(ItemEvent e) {
		if (e.getItem()==checkBox1) {
			System.out.println("Checkbox 1 state changed");
		}
		else if (e.getItem()==checkBox2) {
			System.out.println("Checkbox 2 state changed");
		}
		else if (e.getItem()==checkBox3) {
			System.out.println("Checkbox 3 state changed");
		}
	}

	private static void createAndShowGUI() {

  //Create and set up the window.

  JFrame frame = new HandleJCheckBoxEvent();

  //Display the window.

  frame.pack();

  frame.setVisible(true);

  frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    }

	public static void main(String[] args) {

  //Schedule a job for the event-dispatching thread:

  //creating and showing this application's GUI.

  javax.swing.SwingUtilities.invokeLater(new Runnable() {

public void run() {

    createAndShowGUI(); 

}

  });
    }

}

 
This was an example on how to handle JCheckBox events.