请帮助，我是编程的新手，所以我真的不知道问题是什么以及如何诊断它。我试图将数据写入我创建的访问数据库，但我继续收到以下错误
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at javaapplication1.Registration.BtnRegActionPerformed(Registration.java:267)
at javaapplication1.Registration.access$300(Registration.java:15)
at javaapplication1.Registration$4.actionPerformed(Registration.java:221)
这是我的代码：
package javaapplication1;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
*
* @author Boosta
*/
public class Registration extends javax.swing.JFrame {
private static Statement st;
private static ResultSet rs;
private static Connection conn;
private static String selTable;
public Registration() {
initComponents();
}
public void CreateResultSet(){
try {
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
} catch (ClassNotFoundException ex) {
Logger.getLogger(Registration.class.getName()).log(Level.SEVERE, null, ex);
}
try{
conn = DriverManager.getConnection("jdbc:odbc:cb1");
st = conn.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_READ_ONLY);
String sql = "INSERT INTO Users(Title,FName,SName,IDNO,PAddress,EAddress,Username,Password)" + "VALUES (?,?,?,?,?,?,?,?)";
//st.execute(sql);
rs = st.executeQuery(sql);
}
catch(SQLException ex){
Logger.getLogger(Registration.class.getName()).log(Level.SEVERE, null, ex);
}
}
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {
jLabel1 = new javax.swing.JLabel();
jLabel2 = new javax.swing.JLabel();
jLabel3 = new javax.swing.JLabel();
jLabel4 = new javax.swing.JLabel();
txtName = new javax.swing.JTextField();
txtSname = new javax.swing.JTextField();
txtID = new javax.swing.JTextField();
txtPA = new javax.swing.JTextField();
jLabel5 = new javax.swing.JLabel();
jLabel6 = new javax.swing.JLabel();
txtE = new javax.swing.JTextField();
jLabel7 = new javax.swing.JLabel();
txtUsern = new javax.swing.JTextField();
jLabel8 = new javax.swing.JLabel();
txtPass = new javax.swing.JPasswordField();
jLabel10 = new javax.swing.JLabel();
BtnReg = new javax.swing.JButton();
jButton2 = new javax.swing.JButton();
txtTitle = new javax.swing.JTextField();
jLabel9 = new javax.swing.JLabel();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
getContentPane().setLayout(null);
jLabel1.setFont(new java.awt.Font("Tahoma", 0, 12)); // NOI18N
jLabel1.setForeground(new java.awt.Color(255, 255, 255));
jLabel1.setText("Name");
getContentPane().add(jLabel1);
jLabel1.setBounds(40, 90, 40, 15);
jLabel2.setFont(new java.awt.Font("Tahoma", 0, 12)); // NOI18N
jLabel2.setForeground(new java.awt.Color(255, 255, 255));
jLabel2.setText("Surname");
getContentPane().add(jLabel2);
jLabel2.setBounds(40, 130, 50, 15);
jLabel3.setFont(new java.awt.Font("Tahoma", 0, 12)); // NOI18N
jLabel3.setForeground(new java.awt.Color(255, 255, 255));
jLabel3.setText("ID Number");
getContentPane().add(jLabel3);
jLabel3.setBounds(40, 170, 60, 15);
jLabel4.setFont(new java.awt.Font("Tahoma", 0, 12)); // NOI18N
jLabel4.setForeground(new java.awt.Color(255, 255, 255));
jLabel4.setText("Physical Address");
getContentPane().add(jLabel4);
jLabel4.setBounds(30, 210, 90, 15);
getContentPane().add(txtName);
txtName.setBounds(130, 80, 100, 30);
txtSname.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
txtSnameActionPerformed(evt);
}
});
getContentPane().add(txtSname);
txtSname.setBounds(130, 120, 100, 30);
getContentPane().add(txtID);
txtID.setBounds(130, 160, 190, 30);
getContentPane().add(txtPA);
txtPA.setBounds(130, 200, 250, 30);
jLabel5.setFont(new java.awt.Font("Tahoma", 0, 12)); // NOI18N
jLabel5.setForeground(new java.awt.Color(255, 255, 255));
jLabel5.setText("Title");
getContentPane().add(jLabel5);
jLabel5.setBounds(40, 50, 40, 15);
jLabel6.setFont(new java.awt.Font("Tahoma", 0, 12)); // NOI18N
jLabel6.setForeground(new java.awt.Color(255, 255, 255));
jLabel6.setText("Email Address");
getContentPane().add(jLabel6);
jLabel6.setBounds(30, 250, 80, 15);
txtE.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
txtEActionPerformed(evt);
}
});
getContentPane().add(txtE);
txtE.setBounds(130, 240, 160, 30);
jLabel7.setFont(new java.awt.Font("Tahoma", 0, 12)); // NOI18N
jLabel7.setForeground(new java.awt.Color(255, 255, 255));
jLabel7.setText("Username");
getContentPane().add(jLabel7);
jLabel7.setBounds(30, 290, 70, 15);
getContentPane().add(txtUsern);
txtUsern.setBounds(130, 280, 130, 30);
jLabel8.setFont(new java.awt.Font("Tahoma", 0, 12)); // NOI18N
jLabel8.setForeground(new java.awt.Color(255, 255, 255));
jLabel8.setText("Password");
getContentPane().add(jLabel8);
jLabel8.setBounds(30, 330, 60, 15);
txtPass.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
txtPassActionPerformed(evt);
}
});
getContentPane().add(txtPass);
txtPass.setBounds(130, 320, 130, 30);
jLabel10.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
jLabel10.setForeground(new java.awt.Color(255, 255, 255));
jLabel10.setText("Registration");
getContentPane().add(jLabel10);
jLabel10.setBounds(10, 0, 170, 30);
BtnReg.setText("Submit");
BtnReg.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
BtnRegActionPerformed(evt);
}
});
getContentPane().add(BtnReg);
BtnReg.setBounds(70, 370, 65, 23);
jButton2.setText("Cancel");
getContentPane().add(jButton2);
jButton2.setBounds(170, 370, 65, 23);
getContentPane().add(txtTitle);
txtTitle.setBounds(130, 40, 140, 30);
jLabel9.setIcon(new javax.swing.ImageIcon("C:\\Users\\Boosta\\Pictures\\keyboard-register.jpg")); // NOI18N
jLabel9.setText("jLabel9");
getContentPane().add(jLabel9);
jLabel9.setBounds(0, -20, 410, 440);
pack();
}// </editor-fold>
private void txtSnameActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
}
private void txtEActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
}
private void txtPassActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
}
private void BtnRegActionPerformed(java.awt.event.ActionEvent evt) {
//SaveRecord();
//CreateResultSet();
String Title = txtTitle.getText();
String FName = txtName.getText();
String SName = txtSname.getText();
String IDNO = txtID.getText();
String PAddress = txtPA.getText();
String EAddress = txtE.getText();
String UserName = txtUsern.getText();
String Password = txtPass.getText();
try {
rs.moveToInsertRow();
rs.updateString("Title",Title);
rs.updateString("FName",FName);
rs.updateString("SName",SName);
rs.updateString("IDNO",IDNO);
rs.updateString("PAddress",PAddress);
rs.updateString("EAddress",EAddress);
rs.updateString("UserName",UserName);
rs.updateString("Password",Password);
rs.insertRow();
st.close();
rs.close();
st = conn.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_READ_ONLY);
String sql = "INSERT INTO Users(Title,FName,SName,IDNO,PAddress,EAddress,Username,Password)" + "VALUES (?,?,?,?,?,?,?,?)";
rs = st.executeQuery(sql);
rs.next();
txtTitle.setText(rs.getString("Title"));
txtName.setText(rs.getString("FName"));
txtSname.setText(rs.getString("SName"));
txtID.setText(rs.getString("IDNO"));
txtPA.setText(rs.getString("PAddress"));
txtE.setText(rs.getString("EAddress"));
txtUsern.setText(rs.getString("UserName"));
txtPass.setText(rs.getString("Password"));
} catch (SQLException ex) {
//Logger.getLogger(Registration.class.getName()).log(Level.SEVERE, null, ex);
}
}
/**
* @param args the command line arguments
*/
public static void main(String args[]) {
/* Set the Nimbus look and feel */
//<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
/* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
* For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html
*/
try {
for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
if ("Nimbus".equals(info.getName())) {
javax.swing.UIManager.setLookAndFeel(info.getClassName());
break;
}
}
} catch (ClassNotFoundException ex) {
java.util.logging.Logger.getLogger(Registration.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (InstantiationException ex) {
java.util.logging.Logger.getLogger(Registration.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (IllegalAccessException ex) {
java.util.logging.Logger.getLogger(Registration.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (javax.swing.UnsupportedLookAndFeelException ex) {
java.util.logging.Logger.getLogger(Registration.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
}
//</editor-fold>
/* Create and display the form */
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new Registration().setVisible(true);
}
});
}
// Variables declaration - do not modify
private javax.swing.JButton BtnReg;
private javax.swing.JButton jButton2;
private javax.swing.JLabel jLabel1;
private javax.swing.JLabel jLabel10;
private javax.swing.JLabel jLabel2;
private javax.swing.JLabel jLabel3;
private javax.swing.JLabel jLabel4;
private javax.swing.JLabel jLabel5;
private javax.swing.JLabel jLabel6;
private javax.swing.JLabel jLabel7;
private javax.swing.JLabel jLabel8;
private javax.swing.JLabel jLabel9;
private javax.swing.JTextField txtE;
private javax.swing.JTextField txtID;
private javax.swing.JTextField txtName;
private javax.swing.JTextField txtPA;
private javax.swing.JPasswordField txtPass;
private javax.swing.JTextField txtSname;
private javax.swing.JTextField txtTitle;
private javax.swing.JTextField txtUsern;
// End of variables declaration
}
答案 0 :(得分：0)
您conn变量为空。您正在方法CreateResultSet()中初始化它，这似乎从未被调用过，因为它在异常发生之前只注释了几行。