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AWT AdjustmentListener Interface

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AdjustmentListener

Introduction

The interface AdjustmentListener is used for receiving adjustment events. The class that processes adjustment events needs to implement this interface.

Class declaration

Following is the declaration for java.awt.event.AdjustmentListener interface:

public interface AdjustmentListener
extends EventListener

Interface methods

S.N.Method & Description
1void adjustmentValueChanged(AdjustmentEvent e)Invoked when the value of the adjustable has changed.

Methods inherited

This class inherits methods from the following interfaces:

  • java.awt.event.EventListener

AdjustmentListener Example

Create the following java program using any editor of your choice in say D:/ > AWT > com > adglob > gui >AwtListenerDemo.java

package com.adglob.gui;

import java.awt.*;
import java.awt.event.*;

public class AwtListenerDemo {
   private Frame mainFrame;
   private Label headerLabel;
   private Label statusLabel;
   private Panel controlPanel;

   public AwtListenerDemo(){
      prepareGUI();
   }

   public static void main(String[] args){
      AwtListenerDemo  awtListenerDemo = new AwtListenerDemo();  
      awtListenerDemo.showAdjustmentListenerDemo();
   }

   private void prepareGUI(){
      mainFrame = new Frame("Java AWT 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 Label();
      headerLabel.setAlignment(Label.CENTER);
      statusLabel = new Label();        
      statusLabel.setAlignment(Label.CENTER);
      statusLabel.setSize(350,100);

      controlPanel = new Panel();
      controlPanel.setLayout(new FlowLayout());

      mainFrame.add(headerLabel);
      mainFrame.add(controlPanel);
      mainFrame.add(statusLabel);
      mainFrame.setVisible(true);  
   }

   private void showAdjustmentListenerDemo(){
      headerLabel.setText("Listener in action: AdjustmentListener");      

      ScrollPane panel = new ScrollPane();      
      panel.setBackground(Color.magenta);
      panel.getHAdjustable().addAdjustmentListener(new CustomAdjustmentListener());

      Label msglabel = new Label();
      msglabel.setAlignment(Label.CENTER);   
      msglabel.setText("Welcome to adglob AWT Tutorial.");
      panel.add(msglabel);
      
      controlPanel.add(panel);
      mainFrame.setVisible(true);  
   }

   class CustomAdjustmentListener implements AdjustmentListener {
      public void adjustmentValueChanged(AdjustmentEvent e) {
         statusLabel.setText("Adjustment value: "+Integer.toString(e.getValue()));
      }
   }
}

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

D:\AWT>javac com\adglob\gui\AwtListenerDemo.java

If no error comes that means compilation is successful. Run the program using following command.

D:\AWT>java com.adglob.gui.AwtListenerDemo

Verify the following output

AdjustmentListener

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