下面是我在类Frame1中的全部源代码（只是一个很小的程序）
import java.awt.*;
import javax.swing.*;
import com.borland.jbcl.layout.*;
import java.sql.*;
import java.awt.event.*;

public class Frame1 extends JFrame {
  private BoxLayout2 boxLayout21 = new BoxLayout2();
  ResultSet rs;
  private JTextField jTextField1 = new JTextField();
  private JButton jButton1 = new JButton();

  public Frame1() {
    try {
      jbInit();
      this.show();
      this.pack();
    }
    catch(Exception e) {
      e.printStackTrace();
    }
  }

  public static void main(String[] args) {
    Frame1 frame1 = new Frame1();
    String url="jdbc:odbc:test";
    try{
      Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
      Connection con=DriverManager.getConnection(url,"","");
      String sql="select name,age from test";
      Statement sta=con.createStatement();
      ResultSet rs=sta.executeQuery(sql);
    }
    catch(Exception ex){
      ex.printStackTrace();
    }
  }

  private void jbInit() throws Exception {
    jTextField1.setText("jTextField1");
    this.setDefaultCloseOperation(EXIT_ON_CLOSE);
    this.getContentPane().setLayout(boxLayout21);
    jButton1.setText("jButton1");
    jButton1.addActionListener(new java.awt.event.ActionListener() {
      public void actionPerformed(ActionEvent e) {
        jButton1_actionPerformed(e);
      }
    });
    this.getContentPane().add(jTextField1, null);
    this.getContentPane().add(jButton1, null);
  }

  public void setData(){//点击jButton1时置jTextField1中文本为数据库中的值
    try{
     while（rs.next）
      jTextField1.setText(rs.getString(1));
    }
    catch(Exception ex){
      ex.printStackTrace();
    }
  }

  void jButton1_actionPerformed(ActionEvent e) {
    this.setData();
  }
}

编译时无错,可是当我点击按钮jButton1时出现错误提示如下：
java.lang.NullPointerException

at wmr.Frame1.setData(Frame1.java:66)

at wmr.Frame1.jButton1_actionPerformed(Frame1.java:74)

at wmr.Frame1$1.actionPerformed(Frame1.java:57)

at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1450)

at javax.swing.AbstractButton$ForwardActionEvents.actionPerformed(AbstractButton.java:1504)

at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:378)

at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:250)

at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:216)

at java.awt.Component.processMouseEvent(Component.java:3715)

at java.awt.Component.processEvent(Component.java:3544)

at java.awt.Container.processEvent(Container.java:1164)

at java.awt.Component.dispatchEventImpl(Component.java:2593)

at java.awt.Container.dispatchEventImpl(Container.java:1213)

at java.awt.Component.dispatchEvent(Component.java:2497)

at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:2451)

at java.awt.LightweightDispatcher.processMouseEvent(Container.java:2216)

at java.awt.LightweightDispatcher.dispatchEvent(Container.java:2125)

at java.awt.Container.dispatchEventImpl(Container.java:1200)

at java.awt.Window.dispatchEventImpl(Window.java:914)

at java.awt.Component.dispatchEvent(Component.java:2497)

at java.awt.EventQueue.dispatchEvent(EventQueue.java:339)

at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:131)

at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:98)

at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)

at java.awt.EventDispatchThread.run(EventDispatchThread.java:85)

请您帮我分析一下是什麽原因,是不是需要配置JBuilder7还是...?

ODBC中你建立test文件了吗？如果没建的话，就会出现的。