我有2个按钮用于登录，另一个用于注销。我希望他们两个都表现出不同的时间，但由于某些原因，我不了解他们。当所有信息都保存到文件中时，如果没有信息则显示为null。如果有办法改变，那将非常感激。
import java.awt.BorderLayout;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.GridLayout;
import java.awt.Insets;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.io.FileNotFoundException;
import java.io.PrintWriter;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;
import javax.swing.*;
import javax.swing.event.ListSelectionEvent;
import javax.swing.event.ListSelectionListener;
import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.PlainDocument;
public class MainGUI extends JFrame {
DateFormat dateFormat = new SimpleDateFormat("MM/dd/yyyy HH:mm:ss");
Date date = new Date();
String[] columnNames = {"ID", "NAME", "COURSE", "Professor", "Reason for Tutor", "Login Time", "Logout Time"};
Object[][] data = new Object[25][7];
// table
JTable table = new JTable(data, columnNames) {
@Override
public boolean isCellEditable(int row, int column) {
return false;
}
};
JFrame frame, frame1;
JPanel buttonPanel, buttonPanel2, tablePanel, addPanel, editPanel;
JLabel labelID, labelName, labelCourse, labelProfessor, labelHelp, labelDate, labelDate2;
JTextField txtID, txtName, txtCourse, txtProfessor, txtHelp, txtDate, txtDate2;
JButton btnAdd, btnEdit, btnDelete, btnSort, btnSave, btnAddInput, btnCancel;
int keyCode, rowIndex, rowNumber, noOfStudents;
MainGUI.ButtonHandler bh = new MainGUI.ButtonHandler();
public MainGUI() {
table.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
table.getSelectionModel().addListSelectionListener(new MainGUI.RowListener());
table.getColumnModel().getColumn(1).setPreferredWidth(150);
table.getColumnModel().getColumn(3).setPreferredWidth(100);
table.getColumnModel().getColumn(4).setPreferredWidth(200);
table.getColumnModel().getColumn(5).setPreferredWidth(150);
table.getColumnModel().getColumn(6).setPreferredWidth(150);
table.getTableHeader().setResizingAllowed(false);
table.getTableHeader().setReorderingAllowed(false);
JScrollPane scrollPane = new JScrollPane(table);
btnAdd = new JButton("Login");
btnAdd.addActionListener(bh);
btnEdit = new JButton("EDIT");
btnEdit.addActionListener(bh);
btnEdit.setEnabled(false);
btnDelete = new JButton("DELETE");
btnDelete.addActionListener(bh);
btnDelete.setEnabled(false);
btnSort = new JButton("Logout");
btnSort.addActionListener(bh);
btnSave = new JButton("SAVE");
btnSave.addActionListener(bh);
btnSave.setActionCommand("Save");
btnAddInput = new JButton("Login");
btnAddInput.addActionListener(bh);
btnAddInput.setActionCommand("AddInput");
btnCancel = new JButton("Cancel");
btnCancel.addActionListener(bh);
labelID = new JLabel("ID");
labelName = new JLabel("NAME");
labelCourse = new JLabel("Course");
labelProfessor = new JLabel("Professor");
labelHelp = new JLabel("Reason for Tutoring");
labelDate = new JLabel("Login");
labelDate2 = new JLabel("Logout");
txtID = new JTextField(20);
txtName = new JTextField(20);
txtCourse = new JTextField(20);
txtProfessor = new JTextField(20);
txtHelp = new JTextField(20);
txtDate = new JTextField(20);
txtDate2 = new JTextField(20);
txtID.setDocument(new MainGUI.JTextFieldLimit(15));
txtID.addKeyListener(keyListener);
tablePanel = new JPanel();
tablePanel.setLayout(new BoxLayout(tablePanel, BoxLayout.PAGE_AXIS));
tablePanel.setBorder(BorderFactory.createEmptyBorder(10, 2, 0, 10));
tablePanel.add(table.getTableHeader());
tablePanel.add(table);
buttonPanel = new JPanel();
buttonPanel.setLayout(new GridBagLayout());
GridBagConstraints c = new GridBagConstraints();
c.gridx = 0;
c.gridy = 0;
c.ipady = 20;
c.insets = new Insets(10, 10, 10, 10);
c.fill = GridBagConstraints.HORIZONTAL;
buttonPanel.add(btnAdd, c);
c.gridx = 0;
c.gridy = 1;
c.fill = GridBagConstraints.HORIZONTAL;
c.ipady = 20;
c.insets = new Insets(10, 10, 10, 10);
buttonPanel.add(btnEdit, c);
c.gridx = 0;
c.gridy = 2;
c.fill = GridBagConstraints.HORIZONTAL;
c.ipady = 20;
c.insets = new Insets(10, 10, 10, 10);
buttonPanel.add(btnDelete, c);
c.gridx = 0;
c.gridy = 3;
c.ipady = 20;
c.insets = new Insets(10, 10, 10, 10);
c.fill = GridBagConstraints.HORIZONTAL;
buttonPanel.add(btnSort, c);
c.gridx = 0;
c.gridy = 4;
c.ipady = 20;
c.insets = new Insets(10, 10, 10, 10);
c.fill = GridBagConstraints.HORIZONTAL;
buttonPanel.add(btnSave, c);
frame = new JFrame("Tutoring Database");
frame.setVisible(true);
frame.setResizable(false);
frame.setDefaultCloseOperation(EXIT_ON_CLOSE);
frame.add(tablePanel, BorderLayout.CENTER);
frame.add(buttonPanel, BorderLayout.EAST);
frame.pack();
addPanel = new JPanel();
addPanel.setLayout(new GridBagLayout());
c.insets = new Insets(1, 0, 1, 1);
c.gridx = 0;
c.gridy = 0;
addPanel.add(labelID, c);
c.gridy = 1;
addPanel.add(labelName, c);
c.gridy = 2;
addPanel.add(labelCourse, c);
c.gridy = 3;
addPanel.add(labelProfessor, c);
c.gridy = 4;
addPanel.add(labelHelp, c);
c.gridy = 5;
addPanel.add(labelDate, c);
c.gridy = 6;
addPanel.add(labelDate2, c);
// text fields
c.gridx = 1;
c.gridy = 0;
c.ipady = 1;
addPanel.add(txtID, c);
c.gridy = 1;
c.ipady = 1;
addPanel.add(txtName, c);
c.gridy = 2;
c.ipady = 1;
addPanel.add(txtCourse, c);
c.gridy = 3;
c.ipady = 1;
addPanel.add(txtProfessor, c);
c.gridy = 4;
c.ipady = 1;
addPanel.add(txtHelp, c);
c.gridy = 5;
c.ipady = 1;
addPanel.add(txtDate, c);
c.gridy = 5;
c.ipady = 1;
addPanel.add(txtDate2, c);
buttonPanel2 = new JPanel();
buttonPanel2.setLayout(new GridLayout(1, 1));
buttonPanel2.add(btnAddInput);
buttonPanel2.add(btnCancel);
frame1 = new JFrame("Student Database");
frame1.setVisible(false);
frame1.setResizable(false);
frame1.setDefaultCloseOperation(HIDE_ON_CLOSE);
frame1.add(addPanel, BorderLayout.CENTER);
frame1.add(buttonPanel2, BorderLayout.PAGE_END);
frame1.pack();
}// end
KeyListener keyListener = new KeyListener() {
@Override
public void keyTyped(KeyEvent e) {
}
@Override
public void keyPressed(KeyEvent e) {
keyCode = e.getKeyCode();
if (!(keyCode >= 48 && keyCode <= 57) && !(keyCode >= 96 && keyCode <= 105)
&& !(keyCode >= 37 && keyCode <= 40) && !(keyCode == 127 || keyCode == 8)) {
txtID.setEditable(false);
}
}
@Override
public void keyReleased(KeyEvent e) {
txtID.setEditable(true);
}
};
class RowListener implements ListSelectionListener {
@Override
public void valueChanged(ListSelectionEvent event) {
if (event.getValueIsAdjusting()) {
rowIndex = table.getSelectedRow();
if (data[rowIndex][0] == null || data[rowIndex][0] == "") {
btnEdit.setEnabled(false);
btnDelete.setEnabled(false);
} else {
btnEdit.setEnabled(true);
btnDelete.setEnabled(true);
}
}
}
}
class ButtonHandler implements ActionListener {
@Override
public void actionPerformed(ActionEvent e) {
if (e.getActionCommand().equals("Login")) {
txtID.setText("");
txtName.setText("");
txtCourse.setText("");
txtProfessor.setText("");
txtHelp.setText("");
txtDate.setText(dateFormat.format(date));
frame1.setTitle("Add Student data"); // title bar name for add
frame1.setVisible(true);
} else if (e.getActionCommand().equals("EDIT")) {
txtID.setText(data[rowIndex][0] + "");
txtName.setText(data[rowIndex][1] + "");
txtCourse.setText(data[rowIndex][2] + "");
txtProfessor.setText(data[rowIndex][3] + "");
txtHelp.setText(data[rowIndex][4] + "");
txtDate.setText(data[rowIndex][5] + "");
txtID.setEditable(false);
frame1.setTitle("Edit Student data");
btnAddInput.setActionCommand("Edit2");
btnAddInput.setText("ACCEPT");
frame1.setVisible(true);
} else if (e.getActionCommand().equals("DELETE")) {
int confirm = JOptionPane.showConfirmDialog(frame, "ARE YOU SURE?", "CONFIRM",
JOptionPane.YES_NO_OPTION);
if (confirm == 0) {
rowIndex = table.getSelectedRow();
rowNumber = 0;
noOfStudents--;
for (int i = 0; i <= 10; i++) {
if (rowIndex != i && i <= noOfStudents) {
data[rowNumber][0] = data[i][0];
data[rowNumber][1] = data[i][1];
data[rowNumber][2] = data[i][2];
data[rowNumber][3] = data[i][3];
data[rowNumber][4] = data[i][4];
data[rowNumber][5] = data[i][5];
rowNumber++;
} else if (rowIndex != i && i > noOfStudents) {
data[rowNumber][0] = "";
data[rowNumber][1] = "";
data[rowNumber][2] = "";
data[rowNumber][3] = "";
data[rowNumber][4] = "";
data[rowNumber][5] = "";
rowNumber++;
}
}
if (noOfStudents == 1000) {
btnAdd.setEnabled(false);
}
else {
btnAdd.setEnabled(true);
}
if (noOfStudents == 0) {
btnDelete.setEnabled(false);
btnEdit.setEnabled(false);
} else {
btnDelete.setEnabled(true);
btnEdit.setEnabled(true);
}
rowIndex = table.getSelectedRow();
if (data[rowIndex][0] == null || data[rowIndex][0] == "") {
btnEdit.setEnabled(false);
btnDelete.setEnabled(false);
} else {
btnEdit.setEnabled(true);
btnDelete.setEnabled(true);
}
table.updateUI();
}
} else if (e.getActionCommand().equals("AddInput")) {
if (txtID.getText().isEmpty() || txtName.getText().isEmpty()
|| txtCourse.getText().isEmpty()// /
|| txtProfessor.getText().isEmpty() || txtHelp.getText().isEmpty()) {
JOptionPane.showMessageDialog(null, "PLEASE FILL IN THE BLANKS.", "ERROR!",
JOptionPane.ERROR_MESSAGE);
}
else {
int dup = 0;
for (int i = 0; i < 10; i++) {
if (txtID.getText().equals(data[i][0])) {
JOptionPane.showMessageDialog(null, "ID NUMBER ALREADY EXISTS.", "ERROR!",
JOptionPane.ERROR_MESSAGE);
dup++;
}
}
if (dup == 0) {
rowIndex = table.getSelectedRow();
data[noOfStudents][0] = txtID.getText();
data[noOfStudents][1] = txtName.getText();
data[noOfStudents][2] = txtCourse.getText();
data[noOfStudents][3] = txtProfessor.getText();
data[noOfStudents][4] = txtHelp.getText();
data[noOfStudents][5] = txtDate.getText();
table.updateUI();
frame1.dispose();
noOfStudents++;
if (noOfStudents == 50){
btnAdd.setEnabled(false);
}
else {
btnAdd.setEnabled(true);
}
if (data[rowIndex][0] == null) {
btnEdit.setEnabled(false);
btnDelete.setEnabled(false);
} else {
btnEdit.setEnabled(true);
btnDelete.setEnabled(true);
}
}
}
table.updateUI();
}else if(e.getActionCommand().equals("Save")){
try {
PrintWriter out = new PrintWriter("Tutor.txt");
for(int i = 0; i < 25; i++)
{
for(int j = 0; j < 7; j++)
{
out.print(data[i][j]);
out.print(", ");
if(j == 6){
out.println();
}
} out.flush();
}} catch (FileNotFoundException ex) {
}
} else if (e.getActionCommand().equals("Logout")) {
int confirm = JOptionPane.showConfirmDialog(frame, "ARE YOU SURE?", "CONFIRM",
JOptionPane.YES_NO_OPTION);
if (confirm == 0) {
rowIndex = table.getSelectedRow();
rowNumber = 0;
txtDate2.setText(dateFormat.format(date));
}
}
if (txtID.getText().isEmpty() || txtName.getText().isEmpty()
|| txtCourse.getText().isEmpty() || txtProfessor.getText().isEmpty()
|| txtHelp.getText().isEmpty()|| txtHelp.getText().isEmpty()) {
} else {
data[rowIndex][0] = txtID.getText();
data[rowIndex][1] = txtName.getText();
data[rowIndex][2] = txtCourse.getText();
data[rowIndex][3] = txtProfessor.getText();
data[rowIndex][4] = txtHelp.getText();
data[rowIndex][5] = txtDate.getText();
data[rowIndex][6] = txtDate2.getText();
frame1.dispose();
}
table.updateUI();
}
}
class JTextFieldLimit extends PlainDocument {
private int limit;
JTextFieldLimit(int limit) {
super();
this.limit = limit;
}
JTextFieldLimit(int limit, boolean upper) {
super();
this.limit = limit;
}
@Override
public void insertString(int offset, String str, AttributeSet attr)
throws BadLocationException {
if (str == null) {
return;
}
if ((getLength() + str.length()) <= limit) {
super.insertString(offset, str, attr);
}
}
}
public static void main(String[] args) {
new MainGUI();
}
}
答案 0 :(得分：0)
简单回答游泳你的代码海洋，你需要在你的actionPerformed创建一个新的日期，只要你想显示更新的日期
例如
public void actionPerforemd(ActionEvent e){
...
date = new Date();
// do something with date
...
}