Добавить полосу прокрутки на панель

Question

Я создал простую Java-программу и добавил простой JApplet файл к ресурсам и создал JApplet форму. Затем я сделал простой Java-класс с именем Main_Draw_JPanel. Я добавляю к панели апплета, что один из них является объектом класса Main_Draw_JPanel.

Мне нужна эта панель, чтобы нарисовать на ней дерево структуры данных. почти эти деревья будут расти так, что панель не сможет показать их в полноэкранном режиме. Как я могу добавить JScrollbar на эту панель? Я не знаю, как панель могла перекрасить с помощью прокрутки.

Вот мой код:

import java.awt.Color;
import java.awt.Graphics;
import java.awt.ScrollPane;
import javax.swing.JPanel;

 public class Main_Draw_JPanel extends JPanel
 {     
      public void init (   )
      {

      }
      public void paintComponent ( Graphics g )
      {
           super.paintComponent ( g ) ;
           g.setColor ( Color.red ) ;
           g.fillRect ( 100 , 100 , 200 , 200 ) ;
           g.setColor ( Color.green ) ;
           g.fillRect ( 130 , 130 , 140 , 140 ) ;
           g.setColor ( Color.yellow ) ;
           g.fillRect ( 330 , 330 , 140 , 140 ) ;

      }
 }

Этот второй файл представляет собой простой файл формы апплета!

import JPanel.Main_Draw_JPanel ;
import java.awt.BorderLayout;
import java.awt.ScrollPane;
import javax.swing.JScrollPane;

public class Main_Tree_JApplet extends javax.swing.JApplet
{
     public void init ()
     {
          /*
           * Set the Nimbus look and feel
           */
          //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
        /*
           * If Nimbus (introduced in Java SE 6) is not available, stay with the default
           * look and feel. For details see
           * http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html
           */
          try
          {
               for ( javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels () )
               {
                    if ( "Nimbus".equals ( info.getName () ) )
                    {
                         javax.swing.UIManager.setLookAndFeel ( info.getClassName () );
                         break;
                    }
               }
          }
          catch ( ClassNotFoundException ex )
          {
               java.util.logging.Logger.getLogger ( Main_Tree_JApplet.class.getName () ).log ( java.util.logging.Level.SEVERE , null , ex );
          }
          catch ( InstantiationException ex )
          {
               java.util.logging.Logger.getLogger ( Main_Tree_JApplet.class.getName () ).log ( java.util.logging.Level.SEVERE , null , ex );
          }
          catch ( IllegalAccessException ex )
          {
               java.util.logging.Logger.getLogger ( Main_Tree_JApplet.class.getName () ).log ( java.util.logging.Level.SEVERE , null , ex );
          }
          catch ( javax.swing.UnsupportedLookAndFeelException ex )
          {
               java.util.logging.Logger.getLogger ( Main_Tree_JApplet.class.getName () ).log ( java.util.logging.Level.SEVERE , null , ex );
          }
          //</editor-fold>

          /*
           * Create and display the applet
           */
          resize ( 1000 , 500 ) ;
          //JPanel panel = new JPanel();  
          //jPanel1.add ( jScrollBar1 ) ;

          //add ( sp , "Center" ) ;
          //jScrollBar1.
          try
          {
               java.awt.EventQueue.invokeAndWait ( new Runnable ()
               {

                    public void run ()
                    {
                         initComponents ();
                    }
               } );
          }
          catch ( Exception ex )
          {
               ex.printStackTrace ();
          }
     }

     /**
      * This method is called from within the init() method to initialize the form.
      * WARNING: Do NOT modify this code. The content of this method is always regenerated
      * by the Form Editor.
      */
     @SuppressWarnings ( "unchecked" )
    // <editor-fold defaultstate="collapsed" desc="Generated Code">
    private void initComponents() {

        /*
        jPanel1 = new javax.swing.JPanel();
        */
        jPanel1 = new Main_Draw_JPanel (   ) ;
        jPanel2 = new javax.swing.JPanel();

        setPreferredSize(new java.awt.Dimension(900, 500));

        jPanel1.setBackground(new java.awt.Color(0, 102, 102));

        javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
        jPanel1.setLayout(jPanel1Layout);
        jPanel1Layout.setHorizontalGroup(
            jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 880, Short.MAX_VALUE)
        );
        jPanel1Layout.setVerticalGroup(
            jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 371, Short.MAX_VALUE)
        );

        jPanel2.setBackground(new java.awt.Color(0, 102, 255));

        javax.swing.GroupLayout jPanel2Layout = new javax.swing.GroupLayout(jPanel2);
        jPanel2.setLayout(jPanel2Layout);
        jPanel2Layout.setHorizontalGroup(
            jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 0, Short.MAX_VALUE)
        );
        jPanel2Layout.setVerticalGroup(
            jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 89, Short.MAX_VALUE)
        );

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                .addContainerGap()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
                    .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                    .addComponent(jPanel2, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
                .addContainerGap())
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addContainerGap()
                .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                .addGap(18, 18, 18)
                .addComponent(jPanel2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addContainerGap())
        );
    }// </editor-fold>

    // Variables declaration - do not modify
    /*
    private javax.swing.JPanel jPanel1;
    */
    private Main_Draw_JPanel jPanel1 ;
    private javax.swing.JPanel jPanel2;
    // End of variables declaration
}

Спасибо за ваши ответы!