Question

我的代码遇到了问题。我的代码的逻辑是，当它找不到我输入的用户名时，会出现一个确认框，真正发生的是当在一行中找到输入的用户名时它没有启动确认框“没关系”但它继续搜索每一行并初始化其他{statement}顺便说一句，我的else语句是确认框。

我的代码写的示例data.dat

shawn | qwerty1234
cloe | password1234
jones | shittybrix

当我输入“shawn”时，它会启动我的if语句“那没关系” 但它继续搜索整个字符串，输入的用户名“shawn”变得不等于cloe和jones，它启动else语句，分别给我两个确认框。我想避免这个错误，但我不知道如何。 REGISTER.JAVA中的错误发生

这是我的登录代码：

package login;

import java.awt.HeadlessException;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.*;
import javax.swing.JOptionPane;

public class Login extends javax.swing.JFrame {

    public Login() {
        initComponents0();
    }

    @SuppressWarnings("unchecked")
    private void initComponents0() {

        jLabel1 = new javax.swing.JLabel();
        jLabel2 = new javax.swing.JLabel();
        uname = new javax.swing.JTextField();
        jLabel3 = new javax.swing.JLabel();
        login = new javax.swing.JButton();
        reset = new javax.swing.JButton();
        pwd = new javax.swing.JPasswordField();
        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        jLabel1.setFont(new java.awt.Font("Tahoma", 0, 18)); // NOI18N
        jLabel1.setText("Login Pane");
        jLabel2.setText("User Name:");
        jLabel3.setText("Password:");
        login.setText("Login");
        login.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                String un = uname.getText();
                try {
                    try (BufferedReader br = new BufferedReader(new Filereader("data.dat"))) {
                        String strLine;
                        while ((strLine = br.readLine()) != null) {
                            if (strLine.startsWith(un)) {
                                JOptionPane.showMessageDialog(null, "Hello: " + un, "Registration", JOptionPane.INFORMATION_MESSAGE);
                            } else {
                                int sel = JOptionPane.showConfirmDialog(null, "It seems that you haven't registered yet? \n Lunch Registration Pane?", "Admin", JOptionPane.INFORMATION_MESSAGE);
                                if (sel == JOptionPane.YES_OPTION) {
                                    java.awt.EventQueue.invokeLater(new Runnable() {
                                        @Override
                                        public void run() {
                                            new Register().setVisible(true);
                                        }
                                    });
                                }
                            }
                        }
                    }
                } catch (IOException | HeadlessException ez) {
                    JOptionPane.showMessageDialog(null, "A null file was created in order to \n avoid File Catch errors", "Admin", JOptionPane.INFORMATION_MESSAGE);
                    File file = new File("data.dat");
                    try {
                        try (FileWriter writer = new FileWriter(file, true)) {
                            String data0 = "null";
                            String data1 = "null";
                            writer.write(data0 + " | " + data1 + "\n");
                        }
                    } catch (IOException | HeadlessException z) {
                        JOptionPane.showMessageDialog(null, e);
                    }
                }
            }
        });
        reset.setText("Reset Field");

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
                layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                .addGroup(layout.createSequentialGroup()
                .addContainerGap()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
                .addComponent(jLabel1)
                .addGroup(layout.createSequentialGroup()
                .addComponent(jLabel2)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addComponent(uname, javax.swing.GroupLayout.PREFERRED_SIZE, 300, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addGroup(layout.createSequentialGroup()
                .addComponent(jLabel3)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                .addGroup(layout.createSequentialGroup()
                .addComponent(login, javax.swing.GroupLayout.PREFERRED_SIZE, 137, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                .addComponent(reset, javax.swing.GroupLayout.PREFERRED_SIZE, 137, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addComponent(pwd))))
                .addContainerGap(30, Short.MAX_VALUE)));
        layout.setVerticalGroup(
                layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                .addGroup(layout.createSequentialGroup()
                .addContainerGap()
                .addComponent(jLabel1)
                .addGap(18, 18, 18)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                .addComponent(jLabel2)
                .addComponent(uname, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addGap(18, 18, 18)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                .addComponent(jLabel3)
                .addComponent(pwd, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addGap(18, 18, 18)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                .addComponent(login)
                .addComponent(reset))
                .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)));

        pack();
    }

    /**
     * @param args the command line arguments
     */
    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                new Login().setVisible(true);
            }
        });
    }
    // Variables declaration - do not modify
    private javax.swing.JLabel jLabel1;
    private javax.swing.JLabel jLabel2;
    private javax.swing.JLabel jLabel3;
    private javax.swing.JButton login;
    private javax.swing.JPasswordField pwd;
    private javax.swing.JButton reset;
    private javax.swing.JTextField uname;
    // End of variables declaration
}

这是我在确认框中单击是时启动的注册码

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package login;

import java.awt.HeadlessException;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import javax.swing.JOptionPane;

/**
 *
 * @author Jfetizanan
 */
class Register extends javax.swing.JFrame {

    /**
     * Creates new form GUIREG
     */
    public Register() {
        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")
    private void initComponents() {
        jLabel1 = new javax.swing.JLabel();
        jLabel2 = new javax.swing.JLabel();
        unamereg = new javax.swing.JTextField();
        jLabel3 = new javax.swing.JLabel();
        pwdreg = new javax.swing.JTextField();
        submit = new javax.swing.JButton();
        resetreg = new javax.swing.JButton();
        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        jLabel1.setFont(new java.awt.Font("Tahoma", 0, 18)); // NOI18N
        jLabel1.setText("Registration Pane");
        jLabel2.setText("User Name:");
        jLabel3.setText("Password:");
        submit.setText("Submit");
        submit.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                System.out.println("Runned");
                File file = new File("data.dat");
                try {
                    try (FileWriter writer = new FileWriter(file, true)) {
                        String data0 = unamereg.getText();
                        String data1 = pwdreg.getText();
                        writer.write(data0 + " | " + data1 + "\n");
                    }
                    JOptionPane.showMessageDialog(null, "Registered", "Registration", JOptionPane.INFORMATION_MESSAGE);
                } catch (IOException | HeadlessException z) {
                    JOptionPane.showMessageDialog(null, e);
                }
            }
        });
        resetreg.setText("Reset Field");

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
                layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                .addGroup(layout.createSequentialGroup()
                .addContainerGap()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
                .addComponent(jLabel1)
                .addGroup(layout.createSequentialGroup()
                .addComponent(jLabel2)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addComponent(unamereg))
                .addGroup(layout.createSequentialGroup()
                .addComponent(jLabel3)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                .addComponent(pwdreg)
                .addGroup(layout.createSequentialGroup()
                .addComponent(submit, javax.swing.GroupLayout.PREFERRED_SIZE, 139, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                .addComponent(resetreg, javax.swing.GroupLayout.PREFERRED_SIZE, 139, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(0, 0, Short.MAX_VALUE)))))
                .addContainerGap(42, Short.MAX_VALUE)));
        layout.setVerticalGroup(
                layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                .addGroup(layout.createSequentialGroup()
                .addContainerGap()
                .addComponent(jLabel1)
                .addGap(18, 18, 18)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                .addComponent(jLabel2)
                .addComponent(unamereg, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addGap(18, 18, 18)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                .addComponent(jLabel3)
                .addComponent(pwdreg, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addGap(18, 18, 18)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                .addComponent(submit)
                .addComponent(resetreg))
                .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)));

        pack();
    }
    /**
     * @param args the command line arguments
     */
    // Variables declaration - do not modify
    private javax.swing.JLabel jLabel1;
    private javax.swing.JLabel jLabel2;
    private javax.swing.JLabel jLabel3;
    private javax.swing.JTextField pwdreg;
    private javax.swing.JButton resetreg;
    private javax.swing.JButton submit;
    private javax.swing.JTextField unamereg;
    // End of variables declaration
}

Answer 1

管理通过这个大混乱找到问题。在你的if语句弹出说'helh'，你需要让它摆脱while循环，然后移动else语句。在while语句中复制什么，只是因为它与第一个人不匹配，并不意味着它不会与后一个匹配，所以不要对它们直到最后都大喊大叫。所以它是这样的：

BufferedReader br = new BufferedReader(
        new InputStreamReader(fstream));
String strLine;
boolean registered = false;
while ((strLine = br.readLine()) != null) {
    if (strLine.startsWith(un)) {
        registered = true;
        break;
    }
}
if(registered) {
    //blah
} else {
    //blah
}

此外，您应该将午餐注册更改为启动注册;）

回应你的评论，这是由于这一行：

    setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

你在两个框架中都有这个，它会在你关闭JVM时立即停止它。您希望这是您的登录框架（如果他们关闭登录窗口，停止程序），但不是注册窗口。为此，你只需要javax.swing.WindowConstants.DISPOSE_ON_CLOSE，它表示在关闭框架时会处理框架（良好的清理）。如果处置了所有帧，JVM将结束（假设没有其他线程正在运行），因此只要Login保持打开状态，它就不会退出。

如果并且始于错误

1 个答案: