Mega Code Archive
ComponentListener and ComponentEvent
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/*
* Copyright (c) 1995 - 2008 Sun Microsystems, Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* - Neither the name of Sun Microsystems nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/*
* ComponentEventDemo.java requires no other files.
*/
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.event.ComponentEvent;
import java.awt.event.ComponentListener;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
import javax.swing.JCheckBox;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
public class ComponentEventDemo extends JPanel implements ComponentListener,
ItemListener {
static JFrame frame;
JTextArea display;
JLabel label;
String newline = "\n";
public ComponentEventDemo() {
super(new BorderLayout());
display = new JTextArea();
display.setEditable(false);
JScrollPane scrollPane = new JScrollPane(display);
scrollPane.setPreferredSize(new Dimension(350, 200));
JPanel panel = new JPanel(new BorderLayout());
label = new JLabel("This is a label", JLabel.CENTER);
label.addComponentListener(this);
panel.add(label, BorderLayout.CENTER);
JCheckBox checkbox = new JCheckBox("Label visible", true);
checkbox.addItemListener(this);
checkbox.addComponentListener(this);
panel.add(checkbox, BorderLayout.PAGE_END);
panel.addComponentListener(this);
add(scrollPane, BorderLayout.CENTER);
add(panel, BorderLayout.PAGE_END);
frame.addComponentListener(this);
}
public void itemStateChanged(ItemEvent e) {
if (e.getStateChange() == ItemEvent.SELECTED) {
label.setVisible(true);
// Need to revalidate and repaint, or else the label
// will probably be drawn in the wrong place.
label.revalidate();
label.repaint();
} else {
label.setVisible(false);
}
}
protected void displayMessage(String message) {
// If the text area is not yet realized, and
// we tell it to draw text, it could cause
// a text/AWT tree deadlock. Our solution is
// to ensure that the text area is realized
// before attempting to draw text.
// if (display.isShowing()) {
display.append(message + newline);
display.setCaretPosition(display.getDocument().getLength());
// }
}
public void componentHidden(ComponentEvent e) {
displayMessage(e.getComponent().getClass().getName() + " --- Hidden");
}
public void componentMoved(ComponentEvent e) {
displayMessage(e.getComponent().getClass().getName() + " --- Moved");
}
public void componentResized(ComponentEvent e) {
displayMessage(e.getComponent().getClass().getName() + " --- Resized ");
}
public void componentShown(ComponentEvent e) {
displayMessage(e.getComponent().getClass().getName() + " --- Shown");
}
/**
* 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 = new JFrame("ComponentEventDemo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// Create and set up the content pane.
JComponent newContentPane = new ComponentEventDemo();
newContentPane.setOpaque(true); // content panes must be opaque
frame.setContentPane(newContentPane);
// Display the window.
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args) {
// Schedule a job for the event-dispatching thread:
// creating and showing this application's GUI.
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGUI();
}
});
}
}
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