KeyListener in Java is abstract; cannot be instantiated?

KeyListener listener = new KeyListener();

KeyListener listener = new SomeKeyListenerImplementation();

KeyListener listener = new KeyListener()
{
    public void keyPressed(KeyEvent e) { /* ... */ }

    public void keyReleased(KeyEvent e) { /* ... */ }

    public void keyTyped(KeyEvent e) { /* ... */ }
};

KeyListener listener = new KeyAdapter()
{
    public void keyPressed(KeyEvent e) { /* ... */ }
};