title: What addActionListener does?
body: <p>I have the following code:</p>
  
  <pre><code>JButton button = new JButton("Clear");
  button.addActionListener(this);
  </code></pre>
  
  <p>As far as I understand I create a button on which it is written "Clear". Then I have to associate an action with this button (what will happen if the button is pressed) and it is done by <code>addActionListener</code>. Is it right?</p>
  
  <p>But what I do not understand is where the action is specified. The press of the button should clear text area and, as far as I understand, there should be somewhere a code which clear the text area. But in the given example there is only "this" in the arguments of the <strong><code>addActionListener()</code></strong>.</p>
  
  <p>How the program knows that it should clear the text area when the button is pressed?</p>
  
  <p>If it is needed, the full code is given <a href="http://java.sun.com/docs/books/tutorial/uiswing/examples/events/KeyEventDemoProject/src/events/KeyEventDemo.java" rel="noreferrer">here</a>.</p>