如何从用作提示的JOptionPane返回到JFrame主窗口？

debugcn 发表于 Dev

雅克

这里是一名业余Java程序员。这是我仍在处理的代码。我的计划是使用JOptionPane来显示输入的密码是否正确以及尝试的次数。我的问题是，尝试输入的次数不会改变，如果输入正确的密码，循环就会继续，而不是我打算终止的计划。

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class Password extends JFrame {
private static final int WIDTH = 300;
private static final int HEIGHT = 165;
private static final int tries = 3;

private JLabel passwordLabel;
private JTextField passwordTF;

private JButton okB , cancelB;

private OkButtonHandler obHandler;
private CancelButtonHandler cbHandler;

public Password () {
    passwordLabel = new JLabel ("Input password: " , SwingConstants.LEFT);

    passwordTF = new JTextField (25);

    okB = new JButton ("OK");
    obHandler = new OkButtonHandler();
    okB.addActionListener(obHandler);

    cancelB = new JButton("Cancel");
    cbHandler = new CancelButtonHandler();
    cancelB.addActionListener(cbHandler);

    Container pane = getContentPane();
    pane.setLayout(null);

    pane.add(passwordLabel);
    pane.add(passwordTF);
    pane.add(okB);
    pane.add(cancelB);

    passwordLabel.setBounds(100 , 0 , 100 , 50);
    passwordTF.setBounds(5 , 40 , 275 , 30);
    okB.setBounds(35 , 75 , 100 , 40);
    cancelB.setBounds(150 , 75 , 100 , 40);

    setTitle("Password");
    setSize(WIDTH , HEIGHT);
    setDefaultCloseOperation(EXIT_ON_CLOSE);
    setVisible(true);
}
private class OkButtonHandler implements ActionListener {
    public void actionPerformed (ActionEvent e) {
        String prompt = passwordTF.getText();

        for (int x = 1 ; x<=3 ; x++) {
            if (x==1) {
                if (prompt.equals("Computer")) {
                    passwordTF.setText("");
                    JOptionPane.showMessageDialog(null , "Access granted" , "Password" , JOptionPane.INFORMATION_MESSAGE);
                    break;
                }
                else {
                    passwordTF.setText("");
                    JOptionPane.showMessageDialog(null , "Access denied: "+(tries-1) , "Password" , JOptionPane.WARNING_MESSAGE);
                    continue;
                }
            }
            else if (x==2) {
                if (prompt.equals("Computer")) {
                    passwordTF.setText("");
                    JOptionPane.showMessageDialog(null , "Access granted" , "Password" , JOptionPane.INFORMATION_MESSAGE);
                    break;
                }
                else {
                    passwordTF.setText("");
                    JOptionPane.showMessageDialog(null , "Access denied: "+(tries-2) , "Password" , JOptionPane.WARNING_MESSAGE);
                    continue;
                }
            }
            else if (x==3) {
                if (prompt.equals("Computer")) {
                    passwordTF.setText("");
                    JOptionPane.showMessageDialog(null , "Access granted" , "Password" , JOptionPane.INFORMATION_MESSAGE);
                    break;
                }
                else {
                    passwordTF.setText("");
                    JOptionPane.showMessageDialog(null , "Access denied: System blocked" , "Password" , JOptionPane.WARNING_MESSAGE);
                    continue;
                }
            }
        }
    }
}
private class CancelButtonHandler implements  ActionListener {
    public void actionPerformed (ActionEvent e) {
        System.exit(0);
    }
}
public static void main (String[] args) {
    Password password = new Password ();
}

}

马特·温斯坦利（Matt Winstanley）

在这方面，无需使用for循环，方法是使用

continue;

它将继续通过for循环并依次打印每个错误消息。

每次按下“确定”按钮时调用actionListener时，请尝试如下操作：

private class OkButtonHandler implements ActionListener {
public void actionPerformed (ActionEvent e) {
    String prompt = passwordTF.getText();
            if (prompt.equals("Computer")) {
                passwordTF.setText("");
                JOptionPane.showMessageDialog(null , "Access granted" , "Password" , JOptionPane.INFORMATION_MESSAGE);
            }
            else {
                tries--;
                if (tries != 0){
                passwordTF.setText("");
                JOptionPane.showMessageDialog(null , "Access denied: "+(tries) , "Password" , JOptionPane.WARNING_MESSAGE);
                }
                 else {
                     passwordTF.setText("");
                     JOptionPane.showMessageDialog(null , "Access denied: System blocked" , "Password" , JOptionPane.WARNING_MESSAGE);
                     System.exit(0);
                 }
            }
        }
}