Java Swing Tutorial - Java WindowFocusListener .windowLostFocus (WindowEvent e)








Syntax

WindowFocusListener.windowLostFocus(WindowEvent e) has the following syntax.

void windowLostFocus(WindowEvent e)

Example

In the following code shows how to use WindowFocusListener.windowLostFocus(WindowEvent e) method.

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.event.WindowEvent;
import java.awt.event.WindowFocusListener;
//w  ww.ja  v  a  2  s  .c  o  m
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;

public class Main extends JFrame implements
    WindowFocusListener{
  static Main frame = new Main("WindowEventDemo");
  JTextArea display;

  public static void main(String[] args) {
    frame.setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);
    frame.addComponentsToPane();
    frame.pack();
    frame.setVisible(true);
  }
  private void addComponentsToPane() {
    display = new JTextArea();
    display.setEditable(false);
    JScrollPane scrollPane = new JScrollPane(display);
    scrollPane.setPreferredSize(new Dimension(500, 450));
    getContentPane().add(scrollPane, BorderLayout.CENTER);
    addWindowFocusListener(this);
  }
  public Main(String name) {
    super(name);
  }

  public void windowGainedFocus(WindowEvent e) {
    displayMessage("WindowFocusListener method called: windowGainedFocus.");
  }

  public void windowLostFocus(WindowEvent e) {
    displayMessage("WindowFocusListener method called: windowLostFocus.");
  }

  private void displayMessage(String msg) {
    display.append(msg+"\n");
    System.out.println(msg);
  }
}