当我浏览你的代码时，我发现它有一些严重的问题！
当您按next或时prev。你是openning文件，然后是read三行，然后closing是文件。因为一直在做同样的事情而没有记录你想阅读的位置，所以基本上你看到的是相同的数据（第一个位置的数据）。
解决方案：
假设您需要读取第 i^th 个数据，因此您需要跳过(i-1)3行，然后为三个文本字段读取三行。这里给出了示例代码！
public void readFile(int offset){
//Scanner x = new Scanner(new File("C://wew.txt"));
int i = 0;
while (x.hasNext() && i <= offset ) {
String a = x.next();
String b = x.next();
String c = x.next();
System.out.println("offset: "+offset);
if (i == offset) {
number.setText(a);
name2.setText(b);
lastname2.setText(c);
break;
}
i++;
}
// x.close();
}
只需将您的 readFile() 方法替换为我的方法即可。readFile()在您的 update() 方法readFile(index)中替换int index = 5为int index = 0. 注释掉if (index >= 1)并替换if(index<= 5)为if (index >= 0).
编辑：
这是整个代码！
import javax.swing.*;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.util.*;
import java.io.*;
import javax.swing.JOptionPane;
import javax.swing.event.DocumentListener;
import javax.swing.event.UndoableEditListener;
import javax.swing.text.*;
public class GuiMain implements ActionListener {
static String summary, summary2, summary3;
private Scanner x;
JFrame frame = new JFrame("Generator X");
JPanel p = new JPanel();
JLabel studentno = new JLabel("Student No:");
JLabel name = new JLabel("First name:");
JLabel lastname = new JLabel("Last Name:");
JTextField number = new JTextField();
JTextField name2 = new JTextField();
JTextField lastname2 = new JTextField();
JButton next = new JButton("NEXT---->");
JButton prev = new JButton("<----PREV");
JButton add = new JButton("Add");
JButton save = new JButton("Save");
JButton delete = new JButton("Delete");
JButton edit = new JButton("Edit");
JButton cancel = new JButton("Cancel");
JButton exit = new JButton("Exit");
JButton clear = new JButton("Clear");
static int index = -1;
public void openFile() {
try {
x = new Scanner(new File("C://wew.txt"));
} catch (Exception d) {
}
}
public void readFile(int offset) {
int i = 0;
while (x.hasNext() && i <= offset ) {
String a = x.next();
String b = x.next();
String c = x.next();
System.out.println("offset: "+offset);
if (i == offset) {
number.setText(a);
name2.setText(b);
lastname2.setText(c);
break;
}
i++;
}
}
public void closeFile() {
x.close();
}
public void update() {
openFile();
readFile(index);
closeFile();
}
public GuiMain() {
frame.setSize(300, 500);//frame
frame.setLayout(null);
frame.setVisible(true);
frame.setResizable(false);
studentno.setBounds(30, 30, 80, 60);//LABEL
number.setBounds(100, 45, 100, 25);//TextField
number.addActionListener(this);
//number.setDocument();
//number.setDocument(new JTextFieldLimit(7));
number.setEditable(false);
name.setBounds(30, 70, 100, 65);//LABEL
name2.setBounds(100, 90, 100, 28);//TextField
name2.addActionListener(this);
name2.setEditable(false);
lastname.setBounds(30, 115, 100, 65);//LABEL
lastname2.setBounds(100, 133, 120, 28);//TextField
lastname2.addActionListener(this);
lastname2.setEditable(false);
next.setBounds(150, 170, 100, 30);//Next Button
next.addActionListener(this);
prev.setBounds(50, 170, 100, 30);//Previous Button
prev.addActionListener(this);
add.setBounds(50, 210, 100, 30);
add.addActionListener(this);
save.setBounds(100, 250, 100, 30);//Save Button
save.addActionListener(this);
cancel.setBounds(50, 330, 200, 35);
cancel.addActionListener(this);
delete.setBounds(50, 290, 200, 35);
delete.addActionListener(this);
edit.setBounds(150, 210, 100, 30);
edit.addActionListener(this);
exit.setBounds(50, 370, 200, 35);
exit.addActionListener(this);
frame.add(studentno);
frame.add(name);
frame.add(lastname);
frame.add(number);
frame.add(name2);
frame.add(lastname2);
frame.add(next);
frame.add(prev);
frame.add(add);
frame.add(save);
frame.add(cancel);
frame.add(exit);
frame.add(delete);
frame.add(clear);
}
public void actionPerformed(ActionEvent e) {
if (e.getSource() == cancel) {
number.setEditable(false);
name2.setEditable(false);
lastname2.setEditable(false);
delete.setEnabled(true);
next.setEnabled(true);
prev.setEnabled(true);
edit.setEnabled(true);
}
if (e.getSource() == add) {
number.setEditable(true);
name2.setEditable(true);
lastname2.setEditable(true);
next.setEnabled(true);
prev.setEnabled(false);
edit.setEnabled(false);
delete.setEnabled(false);
number.setText("");
name2.setText("");
lastname2.setText("");
} else if (e.getSource() == save) {//save button
summary = (" " + number.getText());
summary2 = ("" + name2.getText());
summary3 = (" " + lastname2.getText());
String I = GuiMain.summary;
String Love = GuiMain.summary2;
String You = GuiMain.summary3;
try {
BufferedWriter bw = new BufferedWriter(new FileWriter(new File("C://wew.txt"), true));
bw.write(I);
bw.newLine();
bw.write(Love);
bw.newLine();
bw.write(You);
bw.newLine();
bw.close();
JOptionPane.showMessageDialog(frame, "Your File has been Saved");
} catch (IOException E) {
}
} else if (e.getSource() == next) {
//if (index >= 1)//Next Button
index++;
update();
// System.out.println(index);
} else if (e.getSource() == prev) {
if (index >= 0) {
index--;
update();
// System.out.println(index);
}
} else if (e.getSource() == exit) {
JOptionPane.showConfirmDialog(frame, "Want To Exit?");
frame.dispose();
}
}
public static void main(String args[]) {
new GuiMain();
}
}
最后但是同样重要的。首先学习基本的Java概念，相信我，有很多东西要知道！