为什么画图显示不出来呢?

import java.awt.*;
import java.awt.geom.Rectangle2D;
import javax.swing.*;

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */

/*
 * MyJframe.java
 *
 * Created on 2009-8-19, 9:24:05
 */

/**
 *
 * @author Administrator
 */
public class MyJframe extends javax.swing.JFrame {

  /** Creates new form MyJframe */
  public MyJframe() {
  initComponents();
  DrawComponent component=new DrawComponent();
  add(component);
  }

  /** This method is called from within the constructor 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() {

  setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
  setBackground(new java.awt.Color(255, 255, 102));
  setCursor(new java.awt.Cursor(java.awt.Cursor.DEFAULT_CURSOR));
  setLocationByPlatform(true);

  javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
  getContentPane().setLayout(layout);
  layout.setHorizontalGroup(
  layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
  .addGap(0, 427, Short.MAX_VALUE)
  );
  layout.setVerticalGroup(
  layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
  .addGap(0, 372, Short.MAX_VALUE)
  );

  pack();
  }// </editor-fold>

  /**
  * @param args the command line arguments
  */
  public static void main(String args[]) {
  java.awt.EventQueue.invokeLater(new Runnable() {
  public void run() {
  new MyJframe().setVisible(true);
  }
  });
  }

  // Variables declaration - do not modify
  // End of variables declaration

}

class DrawComponent extends JComponent{
  public void paintComponent(Graphics g){
  Graphics2D g2=(Graphics2D)g;
  Rectangle2D rect=new Rectangle2D.Double(100,100,200,200);
  g2.setPaint(Color.ORANGE);
  g2.fill(rect);
  }
}



如题啊..只能显示一个frame 画的图出不来

------解决方案--------------------
布局管理器有问题，netbeans生成的代码和后面的使用add代码增加有冲突的