Question

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());
        }
}                                           

}

Answer 1

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());

Answer 2

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。

Answer 3

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。

error java.sql.SQLException：参数索引超出范围（1>参数个数，为0

3 个答案: