jTextArea1.addKeyListener(new java.awt.event.KeyAdapter() {
      public void keyPressed(KeyEvent e) {
        int key=e.getKeyCode();
        if(key==KeyEvent.VK_TAB){
          jTextArea1.append("Tab Pressed");
        }
      }
    });

class MyAdapter
    extends KeyAdapter {
  public void keyPressed(KeyEvent e) {
    System.out.println("Pressed!");
  }
}