Java KeyEvent KEY_RELEASED
Syntax
KeyEvent.KEY_RELEASED has the following syntax.
public static final int KEY_RELEASED
Example
In the following code shows how to use KeyEvent.KEY_RELEASED field.
/*from w w w . ja v a 2 s.co m*/
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;
public class Main extends JFrame implements KeyListener, ActionListener {
JTextArea displayArea;
JTextField typingArea;
static final String newline = System.getProperty("line.separator");
public static void main(String[] args) {
Main frame = new Main();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.addComponentsToPane();
frame.pack();
frame.setVisible(true);
}
private void addComponentsToPane() {
JButton button = new JButton("Clear");
button.addActionListener(this);
typingArea = new JTextField(20);
typingArea.addKeyListener(this);
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);
}
/** 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();
}
private void displayInfo(KeyEvent e, String keyStatus) {
int id = e.getID();
String keyString;
if (id == KeyEvent.KEY_RELEASED) {
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());
}
}
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