title: show character count in swing gui
body: <p>I have a <code>JTextArea</code> called <code>taMessage</code> which displays a message string. This string can be edited by the user at run time.<br>
  I have a <code>JLabel lblLength</code> to show the number of characters.  I am using <code>lblLength.setText(taMessage.getText().length()+"/ 160");</code> to display the character count.</p>
  
  <p>What event listener should I use for taMessage so that as I keep typing text in my text area, lblLength keeps on updating itself? </p>
  
  <p>Something like we see in sites like way2sms or 160by2, where it shows the number of characters left. </p>