Почему я получаю это сообщение об ошибке компиляции из кода ниже?

(Программа перемещает стрелку в 4 направлениях в зависимости от того, какая клавиша со стрелкой нажата на клавиатуре: d)

Direction.java:41: ошибка: DirectionPanel.DirectionListener не является абстрактным и не переопределяет абстрактный метод keyReleased (KeyEvent) в KeyListener

private class DirectionListener implements KeyListener  {

    //Direction.java

    import javax.swing.*;
    import javax.swing.JFrame;
    import java.awt.*;
    import java.awt.event.*;

    class DirectionPanel extends JPanel  {

      private final int WIDTH = 300, HEIGHT = 200;
      private final int JUMP = 10; //increment for image movement
      private final int IMAGE_SIZE = 31;
      private ImageIcon up, down, right, left, currentImage;
      private int x, y;

      //constructor:
      public DirectionPanel ()  {

      addKeyListener (new DirectionListener());
      x =WIDTH / 2;
      y = HEIGHT / 2;
      up = new ImageIcon ("arrowUp.gif");
      down = new ImageIcon ("arrowDown.gif");
      left = new ImageIcon ("arrowLeft.gif");
      right = new ImageIcon ("arrowRight.gif");

      currentImage = right;

      setBackground (Color.black);
      setPreferredSize (new Dimension(WIDTH, HEIGHT));
      setFocusable(true);
      }

      //draws
      public void paintComponent (Graphics page)  {
        super.paintComponent (page);
        currentImage.paintIcon (this, page, x, y);
      }

      //represents the listener for keyboard activity
      private class DirectionListener implements KeyListener  {
        public void keyPressed (KeyEvent event)  {
          switch (event.getKeyCode())  {
            case KeyEvent.VK_UP:
                currentImage = up;
                y -= JUMP;
                break;
            case KeyEvent.VK_DOWN:
                currentImage = down;
                y += JUMP;
                break;
            case KeyEvent.VK_LEFT:
                currentImage = left;
                x -= JUMP;
                break;
            case KeyEvent.VK_RIGHT:
                currentImage = right;
                x += JUMP;
                break;
          }
        repaint();
        }
      //empty definitions for unused methods
      private void KeyTyped (KeyEvent event) {}
      private void KeyReleased (KeyEvent event) {}

      }
    }


    public class Direction  {

      public static void main (String[] args)  {

      JFrame frame = new JFrame ("Direction");
      frame.setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE);
      frame.getContentPane().add (new DirectionPanel());
      frame.pack();
      frame.setVisible(true);
      }
    }