JPanelをスクロールする

JTextAreaやJTableをJScrollPaneで
スクロールさせるサンプルはよく見かけのですが
JPanelにJScrollPaneで画面をスクロールさせる方法は
見つからなかったので自分で作ってみました。

package jp.co.sakahara;
import javax.swing.*;
import java.awt.Dimension;

import java.awt.Rectangle;

import java.awt.Color;
public class AddPanelToScroll extends JFrame {
    private JPanel jContentPane = null;
    private JPanel panel01 = null;
    private JScrollPane scroll = null;
    private JTextField jTextField01 = null;
    /**

     * This is the default constructor

     */

    public AddPanelToScroll() {

        super();

        initialize();

    }
    /**

     * This method initializes this

     * 

     * @return void

     */

    private void initialize() {

        this.setSize(450, 250);

        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        this.setContentPane(getJContentPane());

        this.setTitle("JScrollPane Test!!");

    }
    /**

     * This method initializes jContentPane

     * 

     * @return javax.swing.JPanel

     */

    private JPanel getJContentPane() {

        if (jContentPane == null) {

            jContentPane = new JPanel();

            jContentPane.setLayout(null);

            jContentPane.add(getScroll());

        }

        return jContentPane;

    }
    /**

     * This method initializes jPanel01

     * 

     * @return javax.swing.JPanel

     */

    private JPanel getJPanel01() {

        if (panel01 == null) {

            panel01 = new JPanel();

            panel01.setLayout(null);

            panel01.setBorder(BorderFactory.createLineBorder(Color.gray, 1));

            panel01.setBackground(Color.lightGray);

            panel01.setPreferredSize(new Dimension(200, 200));

            panel01.add(getJTextField01(), null);

        }

        return panel01;

    }
    /**

     * This method initializes scroll

     * 

     * @return javax.swing.JScrollPane

     */

    private JScrollPane getScroll() {

        if (scroll == null) {

            scroll = new JScrollPane();

            scroll.setBounds(50, 50, 330, 130);

            scroll.setViewportView(getJPanel01());

        }

        return scroll;

    }
    /**

     * This method initializes jTextField01

     * 

     * @return javax.swing.JTextField

     */

    private JTextField getJTextField01() {

        if (jTextField01 == null) {

            jTextField01 = new JTextField();

            jTextField01.setBounds(new Rectangle(40, 20, 230, 100));

        }

        return jTextField01;

    }
    /**

     * mainメソッド

     * 

     * @param args

     */

    public static void main(String[] args) {
        AddPanelToScroll test = new AddPanelToScroll();

        test.setVisible(true);

    }

}