请问大牛，小弟我写的程序编译没有错。解释时老是出现异常：Exception in thread "main" java.lang.NullPointerExcept

import java.awt.*;import java.awt.GridBagConstraints;import java.awt.GridBagLayout;import java.awt.GridLayout;import java.awt.event.ActionEvent;import java.awt.event.ActionListener;import javax.swing.*;public class TestDemo extends JFrame implements ActionListener{    private static final long serialVersionUID = 1L;    private JLabel lbname, lbaddr, lbTel;    private JTextField jfname, jfaddr, jfTel;    private JTextArea taCollect;    private JPanel inputpanel, collectpanel;    private GridBagLayout inputlayout;    private GridBagConstraints constraints;    private Container container;    public TestDemo()    {        super("个人信息");        setSize(300,260);        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);        container=this.getContentPane();        container.setLayout(new GridLayout(2,1));    }    //以设定的网格包布局向面板中添加组件    private void AddComponent(JPanel panel, GridBagLayout Layout, GridBagConstraints gbc,            Component com, int row, int column, int numRows, int numColumns, int Weightx, int Weighty )    {        gbc.gridx = row;        gbc.gridy = column;        gbc.weightx = Weightx;        gbc.weighty = Weighty;        gbc.gridheight = numColumns;        gbc.gridwidth = numRows;        Layout.setConstraints(com, gbc);        panel.add(com);            }    @SuppressWarnings("deprecation")    public void setLayout()    {        inputpanel = new JPanel();        inputlayout = new GridBagLayout();        constraints = new GridBagConstraints();        inputpanel.setLayout(inputlayout);                //创建姓名标签并添加到输入面板        constraints.anchor = GridBagConstraints.CENTER;        lbname = new JLabel("姓名");        constraints.fill = GridBagConstraints.NONE;        AddComponent(inputpanel, inputlayout, constraints, lbname, 0,0,1,1,20,0);        //创建姓名文本框并添加到输入面板        jfname = new JTextField();        constraints.fill = GridBagConstraints.HORIZONTAL;        AddComponent(inputpanel, inputlayout, constraints, jfname, 1,0,1,1,80,100);        //创建住址标签        lbaddr = new JLabel("住址");        constraints.fill = GridBagConstraints.NONE;        AddComponent(inputpanel, inputlayout, constraints, lbaddr, 0,1,1,1,20,0);        //创建住址文本框        jfaddr = new JTextField();        constraints.fill = GridBagConstraints.HORIZONTAL;        AddComponent(inputpanel, inputlayout, constraints, jfaddr, 1,1,1,1,80,100);        //创建电话标签        lbTel = new JLabel("电话");        constraints.fill = GridBagConstraints.NONE;        AddComponent(inputpanel, inputlayout, constraints, lbTel, 0,2,1,1,20,0);        //创建电话文本框        jfaddr = new JTextField();        jfaddr.addActionListener(this);        constraints.fill = GridBagConstraints.HORIZONTAL;        AddComponent(inputpanel, inputlayout, constraints, jfTel, 1,2,1,1,80,100);        //添加汇总信息面板        collectpanel = new JPanel();        collectpanel.setLayout(new BorderLayout());        taCollect = new JTextArea("汇总列表");        taCollect.enable(false);//直接对汇总信息编辑         collectpanel.add(taCollect);        //将输入面板和汇总信息面板添加到框架中        container.add(inputpanel);        container.add(collectpanel);        }        @SuppressWarnings("deprecation")        public static void main(String[] args)        {            TestDemo frame = new TestDemo();            frame.setLayout();            frame.show();                    }        public void actionPerformed(ActionEvent e)        {            if(e.getSource() instanceof JTextField)            {                //想文本框中添加信息                taCollect.append("\n");                taCollect.append(jfname.getText()+"\n");                taCollect.append(jfaddr.getText()+"\n");                taCollect.append(jfTel.getText()+"\n");                            }                    }}