The class FocusAdapter is an abstract (adapter) class for receiving keyboard focus events. All methods of this class are empty. This class is convenience class for creating listener objects.
Following is the declaration for java.awt.event.FocusAdapter class −
public abstract class FocusAdapter extends Object implements FocusListener
Sr.No. | Constructor & Description |
---|---|
1 |
FocusAdapter() |
Sr.No. | Method & Description |
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1 |
void focusGained(FocusEvent e) Invoked when a component gains the keyboard focus. |
This class inherits methods from the following classes −
Create the following Java program using any editor of your choice in say D:/ > SWING > com > tutorialspoint > gui >
SwingAdapterDemo.java
package com.tutorialspoint.gui; import java.awt.*; import java.awt.event.*; import javax.swing.*; public class SwingAdapterDemo { private JFrame mainFrame; private JLabel headerLabel; private JLabel statusLabel; private JPanel controlPanel; public SwingAdapterDemo(){ prepareGUI(); } public static void main(String[] args){ SwingAdapterDemo swingAdapterDemo = new SwingAdapterDemo(); swingAdapterDemo.showFocusAdapterDemo(); } private void prepareGUI(){ mainFrame = new JFrame("Java SWING Examples"); mainFrame.setSize(400,400); mainFrame.setLayout(new GridLayout(3, 1)); headerLabel = new JLabel("",JLabel.CENTER ); statusLabel = new JLabel("",JLabel.CENTER); statusLabel.setSize(350,100); mainFrame.addWindowListener(new WindowAdapter() { public void windowClosing(WindowEvent windowEvent){ System.exit(0); } }); controlPanel = new JPanel(); 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"); JButton okButton = new JButton("OK"); JButton cancelButton = new JButton("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 the command prompt. Go to D:/ > SWING and type the following command.
D:\SWING>javac com\tutorialspoint\gui\SwingAdapterDemo.java
If no error occurs, it means the compilation is successful. Run the program using the following command.
D:\SWING>java com.tutorialspoint.gui.SwingAdapterDemo
Verify the following output.