Exception in thread "main" java.lang.NullPointerException
package   yan1;

import   javax.swing.*;
import   javax.swing.table.*;
import   java.awt.*;
import   java.awt.event.*;
//vist   BBS   java
public   class   Customer   extends   JFrame   {

//   variables   of   labels
JLabel   Heading;

JLabel   labelCustNo;

JLabel   labelCustName;

JLabel   labelCustSex;

JLabel   labelCustAge;

//   variables   for   data   entry   controls
JTextField   textCustNo;

JTextField   textCustName;

JComboBox   comboCustSex;

JTextField   textCustAge;
Customer()   {
super( "Customer ");
Container   con;
con   =   this.getContentPane();
con.setLayout(new   FlowLayout());
//   Initializing   textfield
textCustNo   =   new   JTextField(20);
textCustName   =   new   JTextField(25);
textCustAge   =   new   JTextField();

String   Sex[]   =   {   "Male ",   "Female "   };
comboCustSex   =   new   JComboBox(Sex);
//   Adding   controls   for   Customer   Number
con.add(labelCustNo);
con.add(textCustNo);
//   Adding   controls   for   Customer   Name
con.add(labelCustName);
con.add(textCustName);
//   Adding   controls   for   Customer   Sex
con.add(labelCustSex);
con.add(comboCustSex);
//   Adding   controls   for   Customer   Age
con.add(labelCustAge);
con.add(textCustAge);
//   close   the   program   when   close   button   is   clicked
setDefaultCloseOperation(EXIT_ON_CLOSE);
setSize(350,   250);
show();

}

public   static   void   main(String[]   args)   {
Customer   cust   =   new   Customer();
}
}
错误提示为：
Exception   in   thread   "main "   java.lang.NullPointerException
at   java.awt.Container.addImpl(Unknown   Source)
at   java.awt.Container.add(Unknown   Source)
at   yan1.Customer. <init> (Customer.java:42)
at   yan1.Customer.main(Customer.java:61)
请哪一位高手帮忙看啊～我调试了好久，小弟现在在学java开发环境是eclipse+myEclipse,jdk1.4


------解决方案--------------------
try 一下！！１
------解决方案--------------------
看不懂 。 不过看异常的类型 我觉得可能是你用了一个没有指向任何对象的引用吧。。
------解决方案--------------------
labelXXX都没有初始化，也要labelXXX = new JLabel( "xxx ")的
------解决方案--------------------
con.add(labelCustNo);这里没有new一下的都会空指针