JLabel显示倒计时，java [英] JLabel displaying countdown, java

问题描述

我在一个类（名为Welcome）中有一个statusJLabel，在另一个类中有一个计时器（名为Timer）。现在，第一个显示状态一词，第二个显示倒计时。我希望它的方式，但不知道如何 - 显示10,9,8,7 ... 0（然后转到下一个窗口）。到目前为止我的尝试：

I've got a "status" JLabel in one class (named Welcome) and the timer in another one (named Timer). Right now, the first one displays the word "status" and the second one should be doing the countdown. The way I would like it to be, but don't know how to - display 10, 9, 8, 7 ... 0 (and go to the next window then). My attempts so far:

// class Welcome

setLayout(new BorderLayout());
JPanel area = new JPanel();
JLabel status = new JLabel("status");
area.setBackground(Color.darkGray);
Font font2 = new Font("SansSerif", Font.BOLD, 25);
status.setFont(font2);
status.setForeground(Color.green);      
area.add(status, BorderLayout.EAST); // can I put it in the bottom-right corner?
this.add(area);

和计时器：

 public class Timer implements Runnable {

//  public void runThread() {
//      new Thread(this).start();
//  }

public void setText(final String text) {
    SwingUtilities.invokeLater(new Runnable() {
        public void run() {
            setText(text); // link to status here I guess
        }
    });
}

public void run() {
    for (int i = 10; i > 0; i--) {
        // set the label
        final String text = "(" + i + ") seconds left";
        setText(text);

//          // sleep for 1 second
//          try {
//              Thread.currentThread();
//              Thread.sleep(1000);
//          } catch (Exception ex) {
//          }
    }
    // go to the next window
    UsedBefore window2 = new UsedBefore();
    window2.setVisible(true);
}

public static void main(String[] args) {
    // TODO Auto-generated method stub
    // runThread();
}

} // end class

推荐答案

我同意您应该考虑按照Anh Pham使用Java计时器，但实际上，有几个Timer类可用，并且为了您的目的，Swing Timer而不是java.util.Timer as Anh建议最适合您的目的。

I agree that you should consider using a "Java" Timer as per Anh Pham, but in actuality, there are several Timer classes available, and for your purposes a Swing Timer not a java.util.Timer as suggested by Anh would suit your purposes best.

至于你的问题，它只不过是一个简单的引用问题。给带有标签的类一个公共方法，比如 setCountDownLabelText（String text），然后从包含计时器的类中调用该方法。您需要在另一个类中使用计时器JLabel来引用GUI类。

As for your problem, it's really nothing more than a simple problem of references. Give the class with the label a public method, say setCountDownLabelText(String text), and then call that method from the class that holds the timer. You'll need to have a reference of the GUI class with the timer JLabel in the other class.

例如：

import java.awt.BorderLayout;
import java.awt.CardLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.*;

public class Welcome extends JPanel {
   private static final String INTRO = "intro";
   private static final String USED_BEFORE = "used before";
   private CardLayout cardLayout = new CardLayout();
   private JLabel countDownLabel = new JLabel("", SwingConstants.CENTER);

   public Welcome() {
      JPanel introSouthPanel = new JPanel();
      introSouthPanel.add(new JLabel("Status:"));
      introSouthPanel.add(countDownLabel);

      JPanel introPanel = new JPanel();
      introPanel.setPreferredSize(new Dimension(400, 300));
      introPanel.setLayout(new BorderLayout());
      introPanel.add(new JLabel("WELCOME", SwingConstants.CENTER), BorderLayout.CENTER);
      introPanel.add(introSouthPanel, BorderLayout.SOUTH);

      JPanel usedBeforePanel = new JPanel(new BorderLayout());
      usedBeforePanel.setBackground(Color.pink);
      usedBeforePanel.add(new JLabel("Used Before", SwingConstants.CENTER));

      setLayout(cardLayout);
      add(introPanel, INTRO);
      add(usedBeforePanel, USED_BEFORE);

      new HurdlerTimer(this).start();
   }

   private static void createAndShowUI() {
      JFrame frame = new JFrame("Welcome");
      frame.getContentPane().add(new Welcome());
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.pack();
      frame.setLocationRelativeTo(null);
      frame.setVisible(true);
   }

   public static void main(String[] args) {
      java.awt.EventQueue.invokeLater(new Runnable() {
         public void run() {
            createAndShowUI();
         }
      });
   }

   public void setCountDownLabelText(String text) {
      countDownLabel.setText(text);
   }

   public void showNextPanel() {
      cardLayout.next(this);
   }
}

class HurdlerTimer {
   private static final int TIMER_PERIOD = 1000;
   protected static final int MAX_COUNT = 10;
   private Welcome welcome; // holds a reference to the Welcome class
   private int count;

   public HurdlerTimer(Welcome welcome) {
      this.welcome = welcome; // initializes the reference to the Welcome class.
      String text = "(" + (MAX_COUNT - count) + ") seconds left";
      welcome.setCountDownLabelText(text);
   }

   public void start() {
      new Timer(TIMER_PERIOD, new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
            if (count < MAX_COUNT) {
               count++;
               String text = "(" + (MAX_COUNT - count) + ") seconds left";
               welcome.setCountDownLabelText(text); // uses the reference to Welcome
            } else {
               ((Timer) e.getSource()).stop();
               welcome.showNextPanel();
            }
         }
      }).start();
   }

}

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