Event Handling Using Anonymous Inner Classes (Java)

Event Handling Using Anonymous Inner Classes:

You don’t need to implement any interface with your class, see example below how to use Anonymous inner classes:
Code

import java.awt.*;

import java.awt.event.*;

import javax.swing.*;

public class AnonymousClassExample {

             

              JFrame myFrame = null;

              Container con = null;

              JButton startButton = null;

      

        

      public AnonymousClassExample() {

        

                createComponents();

         }

      public void createComponents() { // initializing GUI interface

         myFrame = new JFrame();

         startButton = new JButton("Hello");

      

         con = myFrame.getContentPane();

         con.setLayout(new FlowLayout());

             

         con.add(startButton);

             

         myFrame.setSize(250,100);

         myFrame.setVisible(true);

         myFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

           

Here, you can see when the user click on startButton the click event is invoked and will display this message to you:  

        // Handling click event on button using Anonymous inner class

        startButton.addActionListener(new ActionListener() {

                          

              public void actionPerformed(ActionEvent ae) {

                          

                     JOptionPane.showMessageDialog(null, "Hello World!!!!");

              }

       });

Here, you can see when the user close the windows/frame this windowClosing event is invoked and while closing displays this message to you:

  

       // Handling window (Frame) closing event, using Anonymous inner class

       myFrame.addWindowListener(new WindowAdapter() {

                    

              public void windowClosing(WindowEvent we) {

                          

                     JOptionPane.showMessageDialog(null, "Good Bye Cruel World");

              }

       });

      

      

Likewise, if your form/window also contains JTextfield then , you want when i press enter in textfield it should display the text from textfield to messagebox so you would do this:

      // Handling TextField keyPressed Event, using Anonymous inner class

      txtInput.addKeyListener(new KeyAdapter() {

      

          public void keyPressed(KeyEvent ke) {

                 

                 if (ke.getKeyCode() == KeyEvent.VK_ENTER) {

                        

                        JOptionPane.showMessageDialog(null, txtInput.getText());

                 }

          }

          

     });

 

}