这是我的代码，它从数据库中检索信息（代码未显示）。然后，它意味着在文本字段中设置字符串文本。但是，当我运行代码时，文本字段中不会显示任何文本。当我使用system.out
时，它会在控制台中打印出值 int id_col = rs.getInt("ID");
String id = Integer.toString(id_col);
String surname = rs.getString("surname");
String forename = rs.getString("forename");
String dob = rs.getString("DOB");
String address = rs.getString("address");
String number = rs.getString("number");
String gender = rs.getString("gender");
String tutor = rs.getString("tutor");
String email = rs.getString("email");
idtext.setText(id);
stext.setText(surname);
ftext.setText(forename);
gtext.setText(gender);
dobtext.setText(dob);
HM.setText(address);
pe.setText(number);
tg.setText(tutor);
ea.setText(email);
完整代码：
package test;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;
import java.sql.ResultSet;
import javax.swing.JOptionPane;
import javax.swing.JFrame;
public class Search extends javax.swing.JFrame {
Connection con;
Statement stmt;
ResultSet rs;
public Search() {
initComponents();
DoConnect();
}
public void DoConnect() {
try {
String host = "jdbc:derby://localhost:1527/Students";
String uName = "admin1";
String uPass = "admin1";
con = DriverManager.getConnection(host, uName, uPass);
stmt = con.createStatement();
String sql = "SELECT * FROM student";
rs = stmt.executeQuery("SELECT * FROM student");
rs.next();
int id_col = rs.getInt("ID");
String id = Integer.toString(id_col);
String surname = rs.getString("surname");
String forename = rs.getString("forename");
String dob = rs.getString("DOB");
String address = rs.getString("address");
String number = rs.getString("number");
String gender = rs.getString("gender");
String tutor = rs.getString("tutor");
String email = rs.getString("email");
idtext.setText(id);
stext.setText(surname);
ftext.setText(forename);
gtext.setText(gender);
dobtext.setText(dob);
HM.setText(address);
pe.setText(number);
tg.setText(tutor);
ea.setText(email);
System.out.println( (id) + " " + (forename) + " " + (surname) + " " + (gender) );
}
catch ( SQLException err ) {
System.out.println( err.getMessage( ) );
}
}
/**
* Creates new form Search
*/
{
initComponents();
}
/**
* 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();
jLabel2 = new javax.swing.JLabel();
jLabel3 = new javax.swing.JLabel();
idtext = new javax.swing.JTextField();
stext = new javax.swing.JTextField();
ftext = new javax.swing.JTextField();
gtext = new javax.swing.JTextField();
jLabel4 = new javax.swing.JLabel();
jLabel5 = new javax.swing.JLabel();
jLabel6 = new javax.swing.JLabel();
jLabel7 = new javax.swing.JLabel();
jLabel8 = new javax.swing.JLabel();
jLabel9 = new javax.swing.JLabel();
dobtext = new javax.swing.JTextField();
HM = new javax.swing.JTextField();
pe = new javax.swing.JTextField();
tg = new javax.swing.JTextField();
ea = new javax.swing.JTextField();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
jLabel1.setText("ID Number");
jLabel2.setHorizontalAlignment(javax.swing.SwingConstants.CENTER);
jLabel2.setText("Surname");
jLabel3.setHorizontalAlignment(javax.swing.SwingConstants.CENTER);
jLabel3.setText("Forename");
idtext.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
idtextActionPerformed(evt);
}
});
ftext.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
ftextActionPerformed(evt);
}
});
gtext.setHorizontalAlignment(javax.swing.JTextField.CENTER);
gtext.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
gtextActionPerformed(evt);
}
});
jLabel4.setHorizontalAlignment(javax.swing.SwingConstants.CENTER);
jLabel4.setText("Date of Birth");
jLabel5.setHorizontalAlignment(javax.swing.SwingConstants.CENTER);
jLabel5.setText("Home Address");
jLabel6.setHorizontalAlignment(javax.swing.SwingConstants.CENTER);
jLabel6.setText("Phone Number");
jLabel7.setHorizontalAlignment(javax.swing.SwingConstants.CENTER);
jLabel7.setText("Gender");
jLabel8.setHorizontalAlignment(javax.swing.SwingConstants.CENTER);
jLabel8.setText("Tutor Group");
jLabel9.setHorizontalAlignment(javax.swing.SwingConstants.CENTER);
jLabel9.setText("Email Address");
dobtext.setHorizontalAlignment(javax.swing.JTextField.CENTER);
dobtext.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
dobtextActionPerformed(evt);
}
});
HM.setHorizontalAlignment(javax.swing.JTextField.CENTER);
pe.setHorizontalAlignment(javax.swing.JTextField.CENTER);
tg.setHorizontalAlignment(javax.swing.JTextField.CENTER);
ea.setHorizontalAlignment(javax.swing.JTextField.CENTER);
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
.addGroup(javax.swing.GroupLayout.Alignment.LEADING, layout.createSequentialGroup()
.addGap(47, 47, 47)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING, false)
.addComponent(jLabel5, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(jLabel4, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(jLabel6, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(jLabel7, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(jLabel8, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(jLabel9, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(gtext)
.addComponent(dobtext)
.addComponent(HM)
.addComponent(pe)
.addComponent(tg)
.addComponent(ea)))
.addGroup(layout.createSequentialGroup()
.addContainerGap(37, Short.MAX_VALUE)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jLabel1)
.addComponent(idtext, javax.swing.GroupLayout.PREFERRED_SIZE, 61, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(30, 30, 30)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
.addComponent(stext)
.addComponent(jLabel2, javax.swing.GroupLayout.DEFAULT_SIZE, 100, Short.MAX_VALUE))
.addGap(34, 34, 34)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jLabel3, javax.swing.GroupLayout.PREFERRED_SIZE, 100, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(ftext, javax.swing.GroupLayout.PREFERRED_SIZE, 100, javax.swing.GroupLayout.PREFERRED_SIZE))))
.addGap(38, 38, 38))
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addContainerGap()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jLabel1)
.addComponent(jLabel2)
.addComponent(jLabel3))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(ftext, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(stext, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addComponent(idtext, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(22, 22, 22)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jLabel7)
.addComponent(gtext, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jLabel4)
.addComponent(dobtext, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jLabel5)
.addComponent(HM, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jLabel6)
.addComponent(pe, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(10, 10, 10)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jLabel8)
.addComponent(tg, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jLabel9)
.addComponent(ea, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addContainerGap(26, Short.MAX_VALUE))
);
pack();
}// </editor-fold>
private void idtextActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
}
private void ftextActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
}
private void gtextActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
}
private void dobtextActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
}
/**
* @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(Search.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (InstantiationException ex) {
java.util.logging.Logger.getLogger(Search.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (IllegalAccessException ex) {
java.util.logging.Logger.getLogger(Search.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (javax.swing.UnsupportedLookAndFeelException ex) {
java.util.logging.Logger.getLogger(Search.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
}
//</editor-fold>
//</editor-fold>
//</editor-fold>
//</editor-fold>
/* Create and display the form */
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new Search().setVisible(true);
}
});
}
// Variables declaration - do not modify
private javax.swing.JTextField HM;
private javax.swing.JTextField dobtext;
private javax.swing.JTextField ea;
private javax.swing.JTextField ftext;
private javax.swing.JTextField gtext;
private javax.swing.JTextField idtext;
private javax.swing.JLabel jLabel1;
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 pe;
private javax.swing.JTextField stext;
private javax.swing.JTextField tg;
// End of variables declaration
}
答案 0 :(得分：1)
问题是你调用了initComponents(); twise。一个在构造函数中：
public Search() {
initComponents();
DoConnect();
}
还有一个：
{
initComponents();
}
尝试删除最后一个块。