What did I do wrong? Exception in thread "main" java.lang.NoSuchMethodError: main
<p>When ever I try to compile and run this code:</p>

<pre><code>import java.awt.GridLayout;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;

public abstract class screen implements ActionListener {
    private JFrame title = new JFrame("Tic-Tac-Toe");
    private JButton play = new JButton("");
    private JButton quit = new JButton("");

    public screen() {

        /* Create Window */
        title.setSize(300,300);
        title.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        title.setLayout(new GridLayout(3,3));

        /* Add Buttons To The Window */
        title.add(play);
        title.add(quit);

        /* Action Listeners */
        play.addActionListener(this);
        quit.addActionListener(this);

        /* Make The Window Visible */
        title.setVisible(true);

        /* Letters */
        play.setText("PLAY");
        quit.setText("QUIT");
    }
}
</code></pre>

<p>I get this:</p>

<blockquote>
  <p>Exception in thread "main" java.lang.NoSuchMethodError: main</p>
</blockquote>

<p>I dont know what I did wrong.</p>

<p>I am a novice.</p>

<p>PLEASE HELP!!!</p>
