我已经花了好几个小时将数据插入jcombobox并且让我感到沮丧 有人可以帮我找到我的错误
这是我的代码
import java.awt.BorderLayout;
import java.awt.EventQueue;
import javax.swing.DefaultListModel;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import javax.swing.JLabel;
import javax.swing.JButton;
import java.awt.GridLayout;
import java.awt.Font;
import java.sql.SQLException;
import java.util.Vector;
import javax.swing.JList;
import javax.swing.JTextField;
import javax.swing.JComboBox;
import java.awt.event.ItemListener;
import java.awt.event.ItemEvent;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
public class StaffEditDelete extends JFrame {
private JPanel contentPane;
private JTextField textField;
private JTextField textField_1;
private JTextField textField_2;
private JTextField textField_3;
private JTextField textField_4;
private JTextField textField_5;
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
StaffEditDelete frame = new StaffEditDelete();
frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Create the frame.
*/
Connect con;
// String []alpha;
Vector<String> alpha;
JComboBox comboBox;
public StaffEditDelete() {
setTitle("Staff");
setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
setBounds(100, 100, 450, 424);
contentPane = new JPanel();
contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
setContentPane(contentPane);
contentPane.setLayout(new BorderLayout(0, 0));
JPanel panel = new JPanel();
contentPane.add(panel, BorderLayout.NORTH);
JLabel lblStaff = new JLabel("Staff");
lblStaff.setFont(new Font("Times New Roman", Font.BOLD, 24));
panel.add(lblStaff);
JPanel panel_1 = new JPanel();
contentPane.add(panel_1, BorderLayout.CENTER);
panel_1.setLayout(new GridLayout(7, 2, 10, 10));
JLabel lblNewLabel = new JLabel("ID");
panel_1.add(lblNewLabel);
con.rs = con.executeQuery("Select * from Detail");
try {
while(con.rs.next())
{
// System.out.println("True");
comboBox.addItem(con.rs.getString(1));
}
} catch (Exception e2) {
// TODO Auto-generated catch block
e2.printStackTrace();
}
comboBox = new JComboBox();
comboBox.addItemListener(new ItemListener() {
public void itemStateChanged(ItemEvent e)
{
String items = e.getSource().toString();
con.rs = con.executeQuery("select * from Staff where [ID Staff ='"+items+"']");
try {
textField.setText(con.rs.getString(2));
textField_1.setText(con.rs.getString(3));
textField_2.setText(con.rs.getString(4));
textField_3.setText(con.rs.getString(5));
textField_4.setText(con.rs.getString(6));
textField_5.setText(con.rs.getString(7));
} catch (SQLException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
}
});
panel_1.add(comboBox);
JLabel lblNewLabel_1 = new JLabel("Nama");
panel_1.add(lblNewLabel_1);
textField = new JTextField();
panel_1.add(textField);
textField.setColumns(10);
JLabel lblNewLabel_2 = new JLabel("Alamat");
panel_1.add(lblNewLabel_2);
textField_1 = new JTextField();
panel_1.add(textField_1);
textField_1.setColumns(10);
JLabel lblNewLabel_3 = new JLabel("Nomor Telepon");
panel_1.add(lblNewLabel_3);
textField_2 = new JTextField();
panel_1.add(textField_2);
textField_2.setColumns(10);
JLabel lblNewLabel_4 = new JLabel("Jabatan");
panel_1.add(lblNewLabel_4);
textField_3 = new JTextField();
panel_1.add(textField_3);
textField_3.setColumns(10);
JLabel lblNewLabel_5 = new JLabel("Password");
panel_1.add(lblNewLabel_5);
textField_4 = new JTextField();
panel_1.add(textField_4);
textField_4.setColumns(10);
JLabel lblNewLabel_6 = new JLabel("Gaji");
panel_1.add(lblNewLabel_6);
textField_5 = new JTextField();
panel_1.add(textField_5);
textField_5.setColumns(10);
JPanel panel_2 = new JPanel();
contentPane.add(panel_2, BorderLayout.SOUTH);
JButton btnEdit = new JButton("Edit");
btnEdit.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
if (cekTelpon())
{
int reply = JOptionPane.showConfirmDialog(null, "Edit "+comboBox.getSelectedItem().toString()+"?","Edit?",JOptionPane.YES_NO_OPTION);
if (reply == JOptionPane.YES_OPTION)
{
con.executeUpdateStaff(comboBox.getSelectedItem().toString(), textField.getText(), textField_1.getText(), textField_2.getText(), textField_3.getText(), textField_4.getText(), textField_5.getText());
JOptionPane.showMessageDialog(null, "Data Berhasil di Edit");
}
} else {
JOptionPane.showMessageDialog(null, "Nomor Telepon Harus Angka", "ERROR", JOptionPane.ERROR_MESSAGE);
}
}
});
panel_2.add(btnEdit);
JButton btnDelete = new JButton("Delete");
btnDelete.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
int reply = JOptionPane.showConfirmDialog(null, "Delete "+comboBox.getSelectedItem().toString()+"?","Delete?",JOptionPane.YES_NO_OPTION);
if(reply == JOptionPane.YES_OPTION)
{
con.executeDeleteStaff(comboBox.getSelectedItem().toString());
JOptionPane.showMessageDialog(null, "Data Berhasil di Delete");
}
}
});
panel_2.add(btnDelete);
JButton btnReset = new JButton("Reset");
btnReset.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
comboBox.setSelectedIndex(0);
con.rs = con.executeQuery("Select * from Staff where [ID Staff] = '"+ comboBox.getSelectedItem().toString()+"'");
try {
textField.setText(con.rs.getString(2));
textField_1.setText(con.rs.getString(3));
textField_2.setText(con.rs.getString(4));
textField_3.setText(con.rs.getString(5));
textField_4.setText(con.rs.getString(6));
textField_5.setText(con.rs.getString(7));
} catch (SQLException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
}
});
panel_2.add(btnReset);
JButton btnCancel = new JButton("Cancel");
btnCancel.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
dispose();
}
});
panel_2.add(btnCancel);
}
public boolean cekTelpon()
{
int flag = 0;
for (int i =0 ;i < textField_2.getText().length();i++)
{
if (textField_2.getText().charAt(i) == '0')
{
flag ++;
}
if (textField_2.getText().charAt(i) == '1')
{
flag ++;
}
if (textField_2.getText().charAt(i) == '2')
{
flag ++;
}
if (textField_2.getText().charAt(i) == '3')
{
flag ++;
}
if (textField_2.getText().charAt(i) == '4')
{
flag ++;
}
if (textField_2.getText().charAt(i) == '5')
{
flag ++;
}
if (textField_2.getText().charAt(i) == '6')
{
flag ++;
}
if (textField_2.getText().charAt(i) == '7')
{
flag ++;
}
if (textField_2.getText().charAt(i) == '8')
{
flag ++;
}
if (textField_2.getText().charAt(i) == '9')
{
flag ++;
}
}
if (flag == 0)
{
return true;
} else
{
return false;
}
}
}
这是我的错误
java.lang.NullPointerException
at StaffEditDelete.<init>(StaffEditDelete.java:85)
at StaffEditDelete$1.run(StaffEditDelete.java:44)
at java.awt.event.InvocationEvent.dispatch(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$000(Unknown Source)
at java.awt.EventQueue$1.run(Unknown Source)
at java.awt.EventQueue$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.AccessControlContext$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)
我已经尝试了几个小时，请帮我找到代码中的错误
答案 0 :(得分：0)
显示java.lang.NullPointerException
在StaffEditDelete。（StaffEditDelete.java:85）
您正在使用JComboBox对象后初始化comboBox。所以这个陈述应该在你正在使用这个对象的while循环之前。
comboBox = new JComboBox();
//should be before this block
try {
while(con.rs.next())
{
// System.out.println("True");
//here you are using comboBox. so it should be initialized before this statement.
comboBox.addItem(con.rs.getString(1));
}
} catch (Exception e2) {
// TODO Auto-generated catch block
e2.printStackTrace();
}//not after this block
还有一个问题是con对象尚未创建。所以也请检查一下。
请看一下这句话。
con.rs = con.executeQuery("Select * from Detail");
此处con和rs是什么。