Introduction
The class FocusAdapter is an abstract (adapter) class for receiving keyboard focus events. All methods of this class are empty. This class is a convenient class for creating listener objects.
Class declaration
Following is the declaration for java.awt.event.FocusAdapter class:
public abstract class FocusAdapter
extends Object
implements FocusListener
Class constructors
| S.N. | Constructor & Description |
|---|---|
| 1 | FocusAdapter() |
Class methods
| S.N. | Method & Description |
|---|---|
| 1 | void focusGained(FocusEvent e)Invoked when a component gains the keyboard focus. |
| 2 | focusLost(FocusEvent e)Invoked when a component loses the keyboard focus. |
Methods inherited
This class inherits methods from the following classes:
- java.lang.Object
FocusAdapter Example
Create the following java program using any editor of your choice in say D:/ > AWT > com > adglob > gui >AwtAdapterDemo.java
package com.adglob.gui;
import java.awt.*;
import java.awt.event.*;
public class AwtAdapterDemo {
private Frame mainFrame;
private Label headerLabel;
private Label statusLabel;
private Panel controlPanel;
public AwtAdapterDemo(){
prepareGUI();
}
public static void main(String[] args){
AwtAdapterDemo awtAdapterDemo = new AwtAdapterDemo();
awtAdapterDemo.showFocusAdapterDemo();
}
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 showFocusAdapterDemo(){
headerLabel.setText("Listener in action: FocusAdapter");
Button okButton = new Button("OK");
Button cancelButton = new Button("Cancel");
okButton.addFocusListener(new FocusAdapter(){
public void focusGained(FocusEvent e) {
statusLabel.setText(statusLabel.getText()
+ e.getComponent().getClass().getSimpleName()
+ " gained focus. ");
}
});
cancelButton.addFocusListener(new FocusAdapter(){
public void focusLost(FocusEvent e) {
statusLabel.setText(statusLabel.getText()
+ e.getComponent().getClass().getSimpleName()
+ " lost focus. ");
}
});
controlPanel.add(okButton);
controlPanel.add(cancelButton);
mainFrame.setVisible(true);
}
}
Compile the program using command prompt. Go to D:/ > AWT and type the following command.
D:\AWT>javac com\adglob\gui\AwtAdapterDemo.java
If no error comes that means compilation is successful. Run the program using following command.
D:\AWT>java com.adglob.gui.AwtAdapterDemo
Verify the following output
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