By Alvin Alexander. Last updated: June 6, 2016
The following Java source code comes from this Oracle URL. I’ve copied it here so I can find it more easily, because I’m currently doing a lot of work with Java/Scala Swing keycode/keystroke events, including KeyListener and KeyEvent types of things.
/**
* Copyright (c) 1995, 2008, Oracle and/or its affiliates. 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 Oracle or 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.
*/
package events;
/*
* KeyEventDemo
*/
import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.event.*;
import javax.swing.*;
public class KeyEventDemo extends JFrame
implements KeyListener,
ActionListener
{
JTextArea displayArea;
JTextField typingArea;
static final String newline = System.getProperty("line.separator");
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 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.
KeyEventDemo frame = new KeyEventDemo("KeyEventDemo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//Set up the content pane.
frame.addComponentsToPane();
//Display the window.
frame.pack();
frame.setVisible(true);
}
private void addComponentsToPane() {
JButton button = new JButton("Clear");
button.addActionListener(this);
typingArea = new JTextField(20);
typingArea.addKeyListener(this);
//Uncomment this if you wish to turn off focus
//traversal. The focus subsystem consumes
//focus traversal keys, such as Tab and Shift Tab.
//If you uncomment the following line of code, this
//disables focus traversal and the Tab events will
//become available to the key event listener.
//typingArea.setFocusTraversalKeysEnabled(false);
displayArea = new JTextArea();
displayArea.setEditable(false);
JScrollPane scrollPane = new JScrollPane(displayArea);
scrollPane.setPreferredSize(new Dimension(375, 125));
getContentPane().add(typingArea, BorderLayout.PAGE_START);
getContentPane().add(scrollPane, BorderLayout.CENTER);
getContentPane().add(button, BorderLayout.PAGE_END);
}
public KeyEventDemo(String name) {
super(name);
}
/** Handle the key typed event from the text field. */
public void keyTyped(KeyEvent e) {
displayInfo(e, "KEY TYPED: ");
}
/** Handle the key pressed event from the text field. */
public void keyPressed(KeyEvent e) {
displayInfo(e, "KEY PRESSED: ");
}
/** Handle the key released event from the text field. */
public void keyReleased(KeyEvent e) {
displayInfo(e, "KEY RELEASED: ");
}
/** Handle the button click. */
public void actionPerformed(ActionEvent e) {
//Clear the text components.
displayArea.setText("");
typingArea.setText("");
//Return the focus to the typing area.
typingArea.requestFocusInWindow();
}
/*
* We have to jump through some hoops to avoid
* trying to print non-printing characters
* such as Shift. (Not only do they not print,
* but if you put them in a String, the characters
* afterward won't show up in the text area.)
*/
private void displayInfo(KeyEvent e, String keyStatus){
//You should only rely on the key char if the event
//is a key typed event.
int id = e.getID();
String keyString;
if (id == KeyEvent.KEY_TYPED) {
char c = e.getKeyChar();
keyString = "key character = '" + c + "'";
} else {
int keyCode = e.getKeyCode();
keyString = "key code = " + keyCode
+ " ("
+ KeyEvent.getKeyText(keyCode)
+ ")";
}
int modifiersEx = e.getModifiersEx();
String modString = "extended modifiers = " + modifiersEx;
String tmpString = KeyEvent.getModifiersExText(modifiersEx);
if (tmpString.length() > 0) {
modString += " (" + tmpString + ")";
} else {
modString += " (no extended modifiers)";
}
String actionString = "action key? ";
if (e.isActionKey()) {
actionString += "YES";
} else {
actionString += "NO";
}
String locationString = "key location: ";
int location = e.getKeyLocation();
if (location == KeyEvent.KEY_LOCATION_STANDARD) {
locationString += "standard";
} else if (location == KeyEvent.KEY_LOCATION_LEFT) {
locationString += "left";
} else if (location == KeyEvent.KEY_LOCATION_RIGHT) {
locationString += "right";
} else if (location == KeyEvent.KEY_LOCATION_NUMPAD) {
locationString += "numpad";
} else { // (location == KeyEvent.KEY_LOCATION_UNKNOWN)
locationString += "unknown";
}
displayArea.append(keyStatus + newline
+ " " + keyString + newline
+ " " + modString + newline
+ " " + actionString + newline
+ " " + locationString + newline);
displayArea.setCaretPosition(displayArea.getDocument().getLength());
}
}
See the URL I linked to for more discussion on this KeyListener/KeyEvent example.
