Mega Code Archive
How to Write a Key Listener
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import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import javax.swing.JFrame;
import javax.swing.JTextField;
public class UsingKeyListener {
public static void main(String[] args) {
JFrame aWindow = new JFrame("This is the Window Title");
aWindow.setBounds(50, 100, 300, 300);
aWindow.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JTextField typingArea = new JTextField(20);
typingArea.addKeyListener(new KeyListener() {
/** 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: ");
}
protected void displayInfo(KeyEvent e, String s) {
String keyString, modString, tmpString, actionString, locationString;
// You should only rely on the key char if the event
// is a key typed event.
int id = e.getID();
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 modifiers = e.getModifiersEx();
modString = "modifiers = " + modifiers;
tmpString = KeyEvent.getModifiersExText(modifiers);
if (tmpString.length() > 0) {
modString += " (" + tmpString + ")";
} else {
modString += " (no modifiers)";
}
actionString = "action key? ";
if (e.isActionKey()) {
actionString += "YES";
} else {
actionString += "NO";
}
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";
}
System.out.println(keyString);
System.out.println(modString);
System.out.println(actionString);
System.out.println(locationString);
}
});
aWindow.add(typingArea);
aWindow.setVisible(true);
}
}
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