使用JTable，在删除DefaultTableModel数据的时候出现异常

使用JTable，在删除DefaultTableModel数据的时候出现错误
import   java.awt.FlowLayout;
import   java.awt.event.ActionEvent;
import   java.awt.event.ActionListener;
import   java.io.BufferedReader;
import   java.io.File;
import   java.io.FileInputStream;
import   java.io.FileNotFoundException;
import   java.io.FileReader;
import   java.io.IOException;
import   java.io.InputStreamReader;
import   java.util.Vector;

import   javax.swing.JButton;
import   javax.swing.JFileChooser;
import   javax.swing.JFrame;
import   javax.swing.JScrollPane;
import   javax.swing.JTable;
import   javax.swing.JTextField;
import   javax.swing.event.ListSelectionEvent;
import   javax.swing.event.ListSelectionListener;
import   javax.swing.table.DefaultTableModel;


public   class   Demo   extends   JFrame   {

final   public   JTextField   name;
final   public   JTextField   jg;
final   public   JTextField   id;
final   public   JTextField   bj;
public   JTable   table;
StringBuffer   s   =   new   StringBuffer();
StringBuffer   sb;
Vector <String>   vector;
DefaultTableModel   dtm;
Vector   titles;
Vector   allrows;
/**
  *   Launch   the   application
  *   @param   args
  */
public   static   void   main(String   args[])   {
try   {
Demo   frame   =   new   Demo();
frame.setVisible(true);
}   catch   (Exception   e)   {
e.printStackTrace();
}
}

/**
  *   Create   the   frame
  */
public   Demo()   {
super();
getContentPane().setLayout(null);
setBounds(100,   100,   500,   375);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

final   JScrollPane   scrollPane   =   new   JScrollPane();
scrollPane.setBounds(98,   106,   302,   120);
getContentPane().add(scrollPane);



bj   =   new   JTextField();
bj.setBounds(275,   10,   84,   19);
getContentPane().add(bj);

id   =   new   JTextField();
id.setBounds(121,   47,   84,   19);
getContentPane().add(id);

jg   =   new   JTextField();
jg.setBounds(275,   47,   84,   19);
getContentPane().add(jg);

final   JButton   button   =   new   JButton();
button.addActionListener(new   ActionListener()   {
public   void   actionPerformed(ActionEvent   e)   {

int   row   =   table.getSelectedRow();
int   rows   =   table.getSelectedRowCount();

Vector   vector=   new   Vector();

vector.add(name.getText());
vector.add(bj.getText());
vector.add(id.getText());
vector.add(jg.getText());

dtm.insertRow(row,   vector);
dtm.removeRow(row+1);
}
});
button.setText( "更新 ");
button.setBounds(190,   77,   93,   23);
getContentPane().add(button);

final   JButton   button_1   =   new   JButton();
button_1.addActionListener(new   ActionListener()   {