title: How can I check when a JFrame has been closed?
body: <p>How do I check when <code>JFrame</code> window is closed?</p>
  
  <pre><code>MediaPanel mediaPanel=new MediaPanel();
  JFrame_of_subtitle frame=new JFrame_of_subtitle(mediaPanel);
  JPanel panel=new JPanel();
  frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  </code></pre>