WindowListener, WindowFocusListener, WindowStateListener : Window Event « Swing Event « Java Tutorial






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 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
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 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * WindowEventDemo
 */

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.Frame;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowEvent;
import java.awt.event.WindowFocusListener;
import java.awt.event.WindowListener;
import java.awt.event.WindowStateListener;

import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class WindowEventDemo extends JFrame implements WindowListener,
    WindowFocusListener, WindowStateListener {
  static final String newline = System.getProperty("line.separator");
  static final String space = "    ";
  static WindowEventDemo frame = new WindowEventDemo("WindowEventDemo");
  JTextArea display;

  public static void main(String[] args) {
    /* Use an appropriate Look and Feel */
    try {
      // UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel");
      // UIManager.setLookAndFeel("com.sun.java.swing.plaf.gtk.GTKLookAndFeel");
      UIManager.setLookAndFeel("javax.swing.plaf.metal.MetalLookAndFeel");
    } catch (UnsupportedLookAndFeelException ex) {
      ex.printStackTrace();
    } catch (IllegalAccessException ex) {
      ex.printStackTrace();
    } catch (InstantiationException ex) {
      ex.printStackTrace();
    } catch (ClassNotFoundException ex) {
      ex.printStackTrace();
    }
    /* Turn off metal's use of bold fonts */
    UIManager.put("swing.boldMetal", Boolean.FALSE);

    // Schedule a job for the event dispatch thread:
    // creating and showing this application's GUI.
    javax.swing.SwingUtilities.invokeLater(new Runnable() {
      public void run() {
        createAndShowGUI();
      }
    });
  }

  /**
   * Create the GUI and show it. For thread safety, this method should be
   * invoked from the event-dispatching thread.
   */

  private static void createAndShowGUI() {
    // Create and set up the window.
    frame.setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);

    // Set up the content pane.
    frame.addComponentsToPane();

    // Display the window.
    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);

    addWindowListener(this);
    addWindowFocusListener(this);
    addWindowStateListener(this);

    checkWM();
  }

  public WindowEventDemo(String name) {
    super(name);
  }

  // Some window managers don't support all window states.
  public void checkWM() {
    Toolkit tk = frame.getToolkit();
    if (!(tk.isFrameStateSupported(Frame.ICONIFIED))) {
      displayMessage("Your window manager doesn't support ICONIFIED.");
    } else
      displayMessage("Your window manager supports ICONIFIED.");
    if (!(tk.isFrameStateSupported(Frame.MAXIMIZED_VERT))) {
      displayMessage("Your window manager doesn't support MAXIMIZED_VERT.");
    } else
      displayMessage("Your window manager supports MAXIMIZED_VERT.");
    if (!(tk.isFrameStateSupported(Frame.MAXIMIZED_HORIZ))) {
      displayMessage("Your window manager doesn't support MAXIMIZED_HORIZ.");
    } else
      displayMessage("Your window manager supports MAXIMIZED_HORIZ.");
    if (!(tk.isFrameStateSupported(Frame.MAXIMIZED_BOTH))) {
      displayMessage("Your window manager doesn't support MAXIMIZED_BOTH.");
    } else {
      displayMessage("Your window manager supports MAXIMIZED_BOTH.");
    }
  }

  public void windowClosing(WindowEvent e) {
    displayMessage("WindowListener method called: windowClosing.");
    // A pause so user can see the message before
    // the window actually closes.
    ActionListener task = new ActionListener() {
      boolean alreadyDisposed = false;

      public void actionPerformed(ActionEvent e) {
        if (frame.isDisplayable()) {
          alreadyDisposed = true;
          frame.dispose();
        }
      }
    };
    Timer timer = new Timer(500, task); // fire every half second
    timer.setInitialDelay(2000); // first delay 2 seconds
    timer.setRepeats(false);
    timer.start();
  }

  public void windowClosed(WindowEvent e) {
    // This will only be seen on standard output.
    displayMessage("WindowListener method called: windowClosed.");
  }

  public void windowOpened(WindowEvent e) {
    displayMessage("WindowListener method called: windowOpened.");
  }

  public void windowIconified(WindowEvent e) {
    displayMessage("WindowListener method called: windowIconified.");
  }

  public void windowDeiconified(WindowEvent e) {
    displayMessage("WindowListener method called: windowDeiconified.");
  }

  public void windowActivated(WindowEvent e) {
    displayMessage("WindowListener method called: windowActivated.");
  }

  public void windowDeactivated(WindowEvent e) {
    displayMessage("WindowListener method called: windowDeactivated.");
  }

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

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

  public void windowStateChanged(WindowEvent e) {
    displayStateMessage(
        "WindowStateListener method called: windowStateChanged.", e);
  }

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

  private void displayStateMessage(String prefix, WindowEvent e) {
    int state = e.getNewState();
    int oldState = e.getOldState();
    String msg = prefix + newline + space + "New state: "
        + convertStateToString(state) + newline + space + "Old state: "
        + convertStateToString(oldState);
    displayMessage(msg);
  }

  private String convertStateToString(int state) {
    if (state == Frame.NORMAL) {
      return "NORMAL";
    }
    String strState = " ";
    if ((state & Frame.ICONIFIED) != 0) {
      strState += "ICONIFIED";
    }
    // MAXIMIZED_BOTH is a concatenation of two bits, so
    // we need to test for an exact match.
    if ((state & Frame.MAXIMIZED_BOTH) == Frame.MAXIMIZED_BOTH) {
      strState += "MAXIMIZED_BOTH";
    } else {
      if ((state & Frame.MAXIMIZED_VERT) != 0) {
        strState += "MAXIMIZED_VERT";
      }
      if ((state & Frame.MAXIMIZED_HORIZ) != 0) {
        strState += "MAXIMIZED_HORIZ";
      }
    }
    if (" ".equals(strState)) {
      strState = "UNKNOWN";
    }
    return strState.trim();
  }
}








15.41.Window Event
15.41.1.The event IDs for the WindowEvent class
15.41.2.Making a Window Handle its Own EventsMaking a Window Handle its Own Events
15.41.3.The WindowListener Interface: events reflecting changes in the state of a window
15.41.4.Using WindowListenerUsing WindowListener
15.41.5.Using Adapter ClassesUsing Adapter Classes
15.41.6.Listens for window iconify and deiconify events, so that it can stop the animation when the window isn't visible.Listens for window iconify and deiconify events, so that it can stop the animation when the window isn't visible.
15.41.7.WindowListener, WindowFocusListener, WindowStateListener
15.41.8.extends WindowAdapter
15.41.9.Handle a window closing event
15.41.10.Setting the Initial Focused Component in a Window
15.41.11.int java.awt.event.WindowEvent.WINDOW_OPENED