是否可以在 Swing 应用程序中间创建暂停? [英] Is it possible to create a pause in the middle of Swing application?

问题描述

我正在处理一个涉及通过从物理卡读取字符串进行访问的项目，以下代码简化了我的程序的要点，但是当我尝试在用户滑动后暂停几秒钟时他的卡，出了点问题，行为不是我所需要的，程序暂停，但颜色的窗格没有改变，标签也没有改变.

I'm working on a project that involves access by reading a String from a physical card, the following code simplifies the main point of my program, however when I try to make a pause for a few seconds after an user has swipe his card, something goes wrong and the behavior is not what I need, the program pauses but the color's pane doesn't change nor the label.

有什么建议吗?

这是代码:

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

public class B2 extends JFrame implements ActionListener {
JLabel lbl;
JButton btn;
JTextField jtf;
String password = "123";

public B2() {
    super("");

    this.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
    this.setLayout(null);
    this.setVisible(true);

    setBounds(0,0,480, 250);
    getContentPane().setBackground(Color.cyan);

    btn = new JButton("OK");
    lbl = new JLabel("Enter your password");
    jtf = new JTextField(25);

    btn.addActionListener(this);
    lbl.setBounds(50, 100, 200, 25);
    btn.setBounds(150, 180, 110, 25);
    jtf.setBounds(20, 180, 110, 25);

    getContentPane().add(btn);
    getContentPane().add(lbl);
    getContentPane().add(jtf);
 }

public void actionPerformed(ActionEvent e) {

    if(jtf.getText().equals(password)) {
        getContentPane().setBackground(Color.green);
        lbl.setText("Welcome");
    } else {
        getContentPane().setBackground(Color.red);
        lbl.setText("Access Denied");
    }

    try {
        Thread.sleep(3000);
    } catch (InterruptedException e1) {
        e1.printStackTrace();
    }

    getContentPane().setBackground(Color.cyan);
    lbl.setText("Enter your password");
}

  public static void main(String[] args) {

  javax.swing.SwingUtilities.invokeLater(new Runnable() {
         @Override
         public void run() {
             B2 frame = new B2();
         }
      });
}
}

推荐答案

使用 Thread.sleep() 可以防止 Swing 在暂停完成之前执行重绘.所以它会改变颜色并同时改变它，你不会看到效果.

Using Thread.sleep() prevents Swing from doing a repaint until the pause has finished. So it will change the color and change it back at the same time and you won't see the effect.

尝试使用 Timer 代替.将此添加到您的代码中，它将起作用:

Try to use a Timer instead. Add this to your code and it will work:

if(jtf.getText().equals(password)) {
    getContentPane().setBackground(Color.green);
    lbl.setText("Welcome");

} else {
    getContentPane().setBackground(Color.red);
    lbl.setText("Access Denied");
}

Timer timer = new Timer(3000, new ActionListener() {
    @Override
    public void actionPerformed(ActionEvent e) {
        getContentPane().setBackground(Color.cyan);
        lbl.setText("Enter your password");
    }
});
timer.setRepeats(false);
timer.start();

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