Definition:
The KeyListener interface is used to track the characters a user types into a text component. The interface is a simple one with only three methods that must be implemented by a class:
public interface KeyListener{
public void keyPressed(KeyEvent e);
public void keyReleased(KeyEvent e);
public void keyTyped(KeyEvent e);
}When a class implements the interface it can listen to key events:
inputText.addKeyListener(new KeyListener()
{
@Override
public void keyPressed(KeyEvent e)
{
//when a key is pressed down then this method is called.
}
@Override
public void keyReleased(KeyEvent e)
{
//when the key is released this method is called.
}
@Override
public void keyTyped(KeyEvent e)
{
//In order for this method to be invoked the key combination
//must include a proper character. Modifying
//(e.g., SHIFT, CTRL) or action (e.g., ENTER, DELETE) keys
//will not trigger this method by themselves.
}
});
To find out more about the KeyListener interface and capturing key events have a look at Using a Key Listener and A KeyListener Example Program.
The KeyEvent object is passed to the KeyListener methods and contains information about the key event that occurs.
