Mega Code Archive
FocusListener and FocusEvent
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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.
*/
/*
* FocusEventDemo.java
*
*/
import java.awt.Container;
import java.awt.Dimension;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import java.awt.event.FocusEvent;
import java.awt.event.FocusListener;
import java.util.Vector;
import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JList;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class FocusEventDemo extends JFrame implements FocusListener {
final static String newline = "\n";
JTextArea display;
public FocusEventDemo(String name) {
super(name);
}
public void addComponentsToPane(final Container pane) {
GridBagLayout gridbag = new GridBagLayout();
pane.setLayout(gridbag);
GridBagConstraints c = new GridBagConstraints();
c.fill = GridBagConstraints.HORIZONTAL;
c.weightx = 1.0; // Make column as wide as possible.
JTextField textField = new JTextField("A TextField");
textField.setMargin(new Insets(0, 2, 0, 2));
textField.addFocusListener(this);
gridbag.setConstraints(textField, c);
add(textField);
c.weightx = 0.1; // Widen every other column a bit, when possible.
c.fill = GridBagConstraints.NONE;
JLabel label = new JLabel("A Label");
label.setBorder(BorderFactory.createEmptyBorder(0, 5, 0, 5));
label.addFocusListener(this);
gridbag.setConstraints(label, c);
add(label);
String comboPrefix = "ComboBox Item #";
final int numItems = 15;
Vector<String> vector = new Vector<String>(numItems);
for (int i = 0; i < numItems; i++) {
vector.addElement(comboPrefix + i);
}
JComboBox comboBox = new JComboBox(vector);
comboBox.addFocusListener(this);
gridbag.setConstraints(comboBox, c);
add(comboBox);
c.gridwidth = GridBagConstraints.REMAINDER;
JButton button = new JButton("A Button");
button.addFocusListener(this);
gridbag.setConstraints(button, c);
add(button);
c.weightx = 0.0;
c.weighty = 0.1;
c.fill = GridBagConstraints.BOTH;
String listPrefix = "List Item #";
Vector<String> listVector = new Vector<String>(numItems);
for (int i = 0; i < numItems; i++) {
listVector.addElement(listPrefix + i);
}
JList list = new JList(listVector);
list.setSelectedIndex(1); // It's easier to see the focus change
// if an item is selected.
list.addFocusListener(this);
JScrollPane listScrollPane = new JScrollPane(list);
gridbag.setConstraints(listScrollPane, c);
add(listScrollPane);
c.weighty = 1.0; // Make this row as tall as possible.
c.gridheight = GridBagConstraints.REMAINDER;
// Set up the area that reports focus-gained and focus-lost events.
display = new JTextArea();
display.setEditable(false);
// The setRequestFocusEnabled method prevents a
// component from being clickable, but it can still
// get the focus through the keyboard - this ensures
// user accessibility.
display.setRequestFocusEnabled(false);
display.addFocusListener(this);
JScrollPane displayScrollPane = new JScrollPane(display);
gridbag.setConstraints(displayScrollPane, c);
add(displayScrollPane);
setPreferredSize(new Dimension(450, 450));
((JPanel) pane).setBorder(BorderFactory.createEmptyBorder(20, 20, 20, 20));
}
public void focusGained(FocusEvent e) {
displayMessage("Focus gained", e);
}
public void focusLost(FocusEvent e) {
displayMessage("Focus lost", e);
}
void displayMessage(String prefix, FocusEvent e) {
display.append(prefix
+ (e.isTemporary() ? " (temporary):" : ":")
+ e.getComponent().getClass().getName()
+ "; Opposite component: "
+ (e.getOppositeComponent() != null ? e.getOppositeComponent()
.getClass().getName() : "null") + newline);
display.setCaretPosition(display.getDocument().getLength());
}
/**
* Create the GUI and show it. For thread safety, this method should be
* invoked from the event dispatch thread.
*/
private static void createAndShowGUI() {
// Create and set up the window.
FocusEventDemo frame = new FocusEventDemo("FocusEventDemo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// Set up the content pane.
frame.addComponentsToPane(frame.getContentPane());
// Display the window.
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args) {
/* Use an appropriate Look and Feel */
try {
// UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel");
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();
}
});
}
}
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