这是我的代码 我写了下面的java方法，当我调用它时，给我错误 1 :)当用户在文本字段中输入challan编号时，我必须更新日期。
public class datechnagemainmenu extends javax.swing.JFrame {
public static final String DATE_FORMAT_NOW = "dd/MMM/YYYY ";
Calendar cal = Calendar.getInstance();
SimpleDateFormat sdf = new SimpleDateFormat(DATE_FORMAT_NOW);
Date date = new Date();
/**
* Creates new form datechnagemainmenu
*/
public datechnagemainmenu() {
initComponents();
String dt = sdf.format(cal.getTime());
System.out.println(dt);
jLabel4.setText(dt);
}
/**
* This method is called from within the constructor to initialize the form.
* WARNING: Do NOT modify this code. The content of this method is always
* regenerated by the Form Editor.
*/
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {
jLabel1 = new javax.swing.JLabel();
jLabel7 = new javax.swing.JLabel();
jPanel1 = new javax.swing.JPanel();
jLabel2 = new javax.swing.JLabel();
jLabel3 = new javax.swing.JLabel();
jLabel4 = new javax.swing.JLabel();
jPanel2 = new javax.swing.JPanel();
jLabel5 = new javax.swing.JLabel();
jSeparator1 = new javax.swing.JSeparator();
jPanel3 = new javax.swing.JPanel();
jLabel6 = new javax.swing.JLabel();
jLabel8 = new javax.swing.JLabel();
jLabel9 = new javax.swing.JLabel();
jTextField1 = new javax.swing.JTextField();
jLabel1.setText("jLabel1");
jLabel7.setText("jLabel7");
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
jPanel1.setBorder(javax.swing.BorderFactory.createTitledBorder(null, "Carlsberg india pvt ltd", javax.swing.border.TitledBorder.CENTER, javax.swing.border.TitledBorder.TOP));
jLabel2.setText("Phone number:42570000");
jLabel3.setText("ver -02/03/1.01");
jLabel4.setText("date");
javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
jPanel1.setLayout(jPanel1Layout);
jPanel1Layout.setHorizontalGroup(
jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel1Layout.createSequentialGroup()
.addGap(106, 106, 106)
.addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jLabel2)
.addGroup(jPanel1Layout.createSequentialGroup()
.addGap(12, 12, 12)
.addComponent(jLabel3, javax.swing.GroupLayout.PREFERRED_SIZE, 124, javax.swing.GroupLayout.PREFERRED_SIZE)))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 36, Short.MAX_VALUE)
.addComponent(jLabel4, javax.swing.GroupLayout.PREFERRED_SIZE, 63, javax.swing.GroupLayout.PREFERRED_SIZE)
.addContainerGap())
);
jPanel1Layout.setVerticalGroup(
jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel1Layout.createSequentialGroup()
.addComponent(jLabel2)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jLabel3)
.addGap(0, 0, Short.MAX_VALUE))
.addGroup(jPanel1Layout.createSequentialGroup()
.addContainerGap()
.addComponent(jLabel4)
.addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
);
jPanel2.setBorder(javax.swing.BorderFactory.createLineBorder(new java.awt.Color(0, 0, 0)));
jLabel5.setText("main menu");
javax.swing.GroupLayout jPanel2Layout = new javax.swing.GroupLayout(jPanel2);
jPanel2.setLayout(jPanel2Layout);
jPanel2Layout.setHorizontalGroup(
jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel2Layout.createSequentialGroup()
.addGap(159, 159, 159)
.addComponent(jLabel5)
.addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
);
jPanel2Layout.setVerticalGroup(
jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel2Layout.createSequentialGroup()
.addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(jLabel5)
.addGap(25, 25, 25))
);
jPanel3.setBorder(javax.swing.BorderFactory.createLineBorder(new java.awt.Color(0, 0, 0)));
jLabel6.setText("Please enter the bill no");
jLabel9.setText("give <zero> to exit");
jTextField1.setText("0");
jTextField1.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jTextField1ActionPerformed(evt);
}
});
javax.swing.GroupLayout jPanel3Layout = new javax.swing.GroupLayout(jPanel3);
jPanel3.setLayout(jPanel3Layout);
jPanel3Layout.setHorizontalGroup(
jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel3Layout.createSequentialGroup()
.addContainerGap()
.addGroup(jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel3Layout.createSequentialGroup()
.addComponent(jLabel6)
.addGap(18, 18, 18)
.addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, 89, javax.swing.GroupLayout.PREFERRED_SIZE)
.addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel3Layout.createSequentialGroup()
.addGap(0, 0, Short.MAX_VALUE)
.addGroup(jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel3Layout.createSequentialGroup()
.addComponent(jLabel8)
.addGap(54, 54, 54))
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel3Layout.createSequentialGroup()
.addComponent(jLabel9)
.addContainerGap())))))
);
jPanel3Layout.setVerticalGroup(
jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel3Layout.createSequentialGroup()
.addGap(18, 18, 18)
.addGroup(jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jLabel6)
.addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(18, 18, 18)
.addComponent(jLabel8)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jLabel9)
.addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
);
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(jSeparator1, javax.swing.GroupLayout.Alignment.TRAILING)
.addComponent(jPanel2, javax.swing.GroupLayout.Alignment.TRAILING, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(jPanel3, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addComponent(jPanel1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jSeparator1, javax.swing.GroupLayout.PREFERRED_SIZE, 20, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(18, 18, 18)
.addComponent(jPanel2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(27, 27, 27)
.addComponent(jPanel3, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(0, 7, Short.MAX_VALUE))
);
pack();
}// </editor-fold>
private void jTextField1ActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
//System.out.println(jTextField1);
System.out.println("gfj");
if (evt.getSource() == jTextField1) //add
{
try {
String host = "jdbc:mysql://localhost:3306/indospirit";
String uName = "root";
String uPass = "paras123";
//Class.forName("com.mysql.jdbc.Driver").newInstance();
java.sql.Driver d = new com.mysql.jdbc.Driver();
Connection con = DriverManager.getConnection(host, uName, uPass);
String sql =("update challan set date=('dt') where challan_no='"+jTextField1+"' ");
System.out.println(sql);
PreparedStatement ps;
ps = con.prepareStatement(sql);
ps.setString(1,jTextField1.getText().trim());
ps.setString(2,jLabel4.getText().trim());
int i = ps.executeUpdate();
if(i>0)
JOptionPane.showMessageDialog(null,"Record Updated");
else
JOptionPane.showMessageDialog(null,"Record NOT Updated");
}
catch (SQLException ex) {
System.err.println(ex.toString());
} catch (Exception ex1) {
System.err.println(ex1.toString());
}
}
}
答案 0 :(得分：2)
这一行
String sql =("update challan set date=('dt') where challan_no='"+jTextField1+"' ");
需要看起来像这样
String sql =("update challan set date=? where challan_no=?");
根据？改变指数？在查询中
ps.setString(1,jTextField1.getText().trim());
ps.setString(2,jLabel4.getText().trim());
答案 1 :(得分：1)
这是一个SQL异常。您已将参数传递给预准备语句，但尚未在SQL字符串（Statement）中使用它们。
答案 2 :(得分：0)
这不是Swing错误，而是SQL错误。只使用SQL代码粘贴方法就可以更容易阅读。
您准备好的语句没有任何参数，因此当您尝试设置值时，您会收到该错误。使用 ？用于参数。有关详细信息，请参阅http://docs.oracle.com/javase/tutorial/jdbc/basics/prepared.html。