$show=/label

Java Event Handler - Events and Listeners Examples

SHARE:

A quick guide to event handlers in java. How to add events and listeners to the buttons, text fields, and for different actions of the keyboard.

1. Overview

In this tutorial, We'll learn how to work with event handlers in java.

How to add events to the actions of users and work with the listeners in java.

When you are working on GUI based projects using AWT or Applets then you might have seen the scenarios where you need to change the state of an object from one form to another.

For example, add action when a button is pressed or when the text is entered then enable another text box.

Java Event Handler - Events and Listeners Examples


2. Java Event classes and Interfaces


java.event.awt package contains all events and listeners interfaces.

Event classs --> Event listener

2.1 ActionEvent-->ActionListener
2.2 MouseEvent-->MouseListener and MouseMotionListener
2.3 MouseWheelEvent-->MouseWheelListener
2.4 KeyEvent-->KeyListener
2.5 ItemEvent-->ItemListener
2.6 TextEvent-->TextListener
2.7 AdjustmentEvent-->AdjustmentListener
2.8 WindowEvent-->WindowListener
2.9 ComponentEvent-->ComponentListener
2.10 ContainerEvent-->ContainerListener
2.11 FocusEvent-->FocusListener

3. Steps to add Events and Listeners - Example


First, we need to understand the use case and pick the right interface.

Now, we want to change the text field text when the button is clicked.

Step 1:

Implement the ActionListener interface.

Step 2:

Implement actionPerformed() method. Inside this, we need to change the text field contents using textField.setText() method.

Step 3:

Add the action listener created to the button. You need to call the button.addActionListener() method and pass the instance of ActionListener implementation object.

Look at the below example.

This program first displays the window and a text field with the default text "Enter your name". This window is displayed with a button.

When the button is pressed then this text box text has to be changed to the "hello developer".

Example
package com.javaprogramto.programs.events;

import java.awt.Button;
import java.awt.Frame;
import java.awt.TextField;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

public class JaveEventHandlerExample {

	public static void main(String[] args) {
		new ButtonEvent();
	}
}

class ButtonEvent extends Frame implements ActionListener {

	TextField textField;

	ButtonEvent() {

		textField = new TextField();
		textField.setText("Enter your name");
		textField.setBounds(70, 60, 180, 30);
		Button b = new Button("click me");
		b.setBounds(110, 130, 90, 40);

		b.addActionListener(this);

		add(b);
		add(textField);
		setSize(300, 300);
		setLayout(null);
		setVisible(true);
	}

	public void actionPerformed(ActionEvent e) {
		textField.setText("hello developer");
	}
}

Output:

java action event listener 1


java action event listener 2


4. Adding Listener from Custom class


In the above example, creating and adding action listeners are done within the same class but now let us see how to separate the action listener. How to attach the action listener to the button.

First, create a separate action listener class.
class ActionEventListner implements ActionListener {

	ButtonEvent buttonEvent;

	public ActionEventListner(ButtonEvent buttonEvent) {
		this.buttonEvent = buttonEvent;
	}

	@Override
	public void actionPerformed(ActionEvent e) {
		buttonEvent.textField.setText("hello developer");

	}
}

Create the main class which extends Frame and pass the ActionEventListener object to the button of addActionListner() method.
import java.awt.Button;
import java.awt.Frame;
import java.awt.TextField;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

public class JaveEventHandlerExample2 {

	public static void main(String[] args) {
		new ButtonEvent();
	}
}

class ButtonEvent extends Frame {

	TextField textField;

	ButtonEvent() {

		textField = new TextField();
		textField.setText("Enter your name");
		textField.setBounds(70, 60, 180, 30);
		Button b = new Button("click me");
		b.setBounds(110, 130, 90, 40);

		b.addActionListener(new ActionEventListner(this));

		add(b);
		add(textField);
		setSize(300, 300);
		setLayout(null);
		setVisible(true);
	}

}

This program also produces the same output.

5. Conclusion


In this article, we've seen how to add the action listeners for an event in java using java event handler concept.


COMMENTS

BLOGGER

About Us

Author: Venkatesh - I love to learn and share the technical stuff.
Name

accumulo,1,ActiveMQ,2,Adsense,1,API,37,ArrayList,18,Arrays,21,Bean Creation,3,Bean Scopes,1,BiConsumer,1,Blogger Tips,1,Books,1,C Programming,1,Collection,8,Collections,32,Collector,1,Command Line,1,Compile Errors,1,Configurations,7,Constants,1,Control Statements,8,Conversions,6,Core Java,135,Corona India,1,Create,2,CSS,1,Date,3,Date Time API,38,Dictionary,1,Difference,2,Download,1,Eclipse,3,Efficiently,1,Error,1,Errors,1,Exceptions,7,Fast,1,Files,17,Float,1,Font,1,Form,1,Freshers,1,Function,3,Functional Interface,2,Garbage Collector,1,Generics,4,Git,9,Grant,1,Grep,1,HashMap,2,HomeBrew,2,HTML,2,HttpClient,2,Immutable,1,Installation,1,Interview Questions,6,Iterate,2,Jackson API,3,Java,32,Java 10,1,Java 11,6,Java 12,5,Java 13,2,Java 14,2,Java 8,127,Java 8 Difference,2,Java 8 Stream Conversions,4,java 8 Stream Examples,12,Java 9,1,Java Conversions,14,Java Design Patterns,1,Java Files,1,Java Program,3,Java Programs,113,Java Spark,1,java.lang,4,java.util. function,1,JavaScript,1,jQuery,1,Kotlin,11,Kotlin Conversions,6,Kotlin Programs,10,Lambda,2,lang,29,Leap Year,1,live updates,1,LocalDate,1,Logging,1,Mac OS,3,Math,1,Matrix,6,Maven,1,Method References,1,Mockito,1,MongoDB,3,New Features,1,Operations,1,Optional,6,Oracle,5,Oracle 18C,1,Partition,1,Patterns,1,Programs,1,Property,1,Python,2,Quarkus,1,Read,1,Real Time,1,Recursion,2,Remove,2,Rest API,1,Schedules,1,Serialization,1,Servlet,2,Sort,1,Sorting Techniques,8,Spring,2,Spring Boot,23,Spring Email,1,Spring MVC,1,Streams,29,String,61,String Programs,28,String Revese,1,Swing,1,System,1,Tags,1,Threads,11,Tomcat,1,Tomcat 8,1,Troubleshoot,24,Unix,3,Updates,3,util,5,While Loop,1,
ltr
item
JavaProgramTo.com: Java Event Handler - Events and Listeners Examples
Java Event Handler - Events and Listeners Examples
A quick guide to event handlers in java. How to add events and listeners to the buttons, text fields, and for different actions of the keyboard.
https://1.bp.blogspot.com/-tTfFWkBE0nM/YZujA6dGIkI/AAAAAAAADiE/_mVM7ip7O6ErbuS7mRGjDDq4-YRamoeMgCLcBGAsYHQ/w400-h286/Java%2BEvent%2BHandler%2B-%2BEvents%2Band%2BListeners%2BExamples.png
https://1.bp.blogspot.com/-tTfFWkBE0nM/YZujA6dGIkI/AAAAAAAADiE/_mVM7ip7O6ErbuS7mRGjDDq4-YRamoeMgCLcBGAsYHQ/s72-w400-c-h286/Java%2BEvent%2BHandler%2B-%2BEvents%2Band%2BListeners%2BExamples.png
JavaProgramTo.com
https://www.javaprogramto.com/2021/11/java-event-handler.html
https://www.javaprogramto.com/
https://www.javaprogramto.com/
https://www.javaprogramto.com/2021/11/java-event-handler.html
true
3124782013468838591
UTF-8
Loaded All Posts Not found any posts VIEW ALL Readmore Reply Cancel reply Delete By Home PAGES POSTS View All RECOMMENDED FOR YOU LABEL ARCHIVE SEARCH ALL POSTS Not found any post match with your request Back Home Sunday Monday Tuesday Wednesday Thursday Friday Saturday Sun Mon Tue Wed Thu Fri Sat January February March April May June July August September October November December Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec just now 1 minute ago $$1$$ minutes ago 1 hour ago $$1$$ hours ago Yesterday $$1$$ days ago $$1$$ weeks ago more than 5 weeks ago Followers Follow THIS PREMIUM CONTENT IS LOCKED STEP 1: Share to a social network STEP 2: Click the link on your social network Copy All Code Select All Code All codes were copied to your clipboard Can not copy the codes / texts, please press [CTRL]+[C] (or CMD+C with Mac) to copy Table of Content