Can not find symbol
<p>When I ran this program:</p>

<pre><code>import javax.swing.*;
import java.awt.*;

public class DrawApplet extends JApplet{

    public void init () {

        Container content_pane = getContentPane ();
        // Create an instance of DrawingPanel
        int x=1000, y=1000;

        content_pane.setSize(x, y);

        // And add the DrawingPanel to the content pane.
        main_panel drawing_panel = new main_panel(x,y);
        content_pane.add(drawing_panel);
    }
}
</code></pre>

<p>it showed an error:</p>

<pre><code>DrawApplet.java:16: error: cannot find symbol
main_panel drawing_panel = new main_panel(x,y);
     ^
symbol:   class main_panel
location: class DrawApplet
DrawApplet.java:16: error: cannot find symbol
main_panel drawing_panel = new main_panel(x,y);
                                    ^
symbol:   class main_panel
location: class DrawApplet
2 errors
</code></pre>
