title: activate and deactivate ComboBox
body: <p>How can I make the comboBox available when the checkBox was uncheck (vice versa)</p>
  
  <p>Why the comboBox is still disable after I unChecked the checkBox? </p>
  
  <pre><code>choice [] = {"A","B","C"};
  JComboBox a = new JComboBox(choice);
  
  JCheckBox chk = new JCheckBox("choice");
  
  ...
  a.addActionListener(this);
  chk.addActionListener(this);
  ...
  
  public void actionPerformed(ActionEvent e) {
  
     //disable the a comboBox when the checkBox chk was checked
    if(e.getSource()==chk)
      a.setEnabled(false);
  
    //enable the a comboBox when the checkBox chk was unchecked
    else if(e.getSource()!=chk)
      a.setEnabled(true);
  }
  </code></pre>