Question

当用户点击JFrame的红色“X”按钮时，如何检测JFrame是打开还是关闭？我有一个摆动计时器，JFrame不断更新它的标签，直到用户关闭JFrame。

int delay = 1000;           //milliseconds    

final Timer timer = new Timer(delay, null);
timer.addActionListener(new ActionListener() {
    public void actionPerformed(ActionEvent evt) {
        tempLabel.setVisible(true);
        String tmp = "test";                           
        tempLabel.setText("Temperature :  " + tmp);
        // timer.stop();
    }
});

timer.start();

Answer 1

您必须实现WindowStateListener或WindowListener。如果您使用WindowListener，它可能如下所示：

import java.awt.event.WindowEvent;
import java.awt.event.WindowListener;
import javax.swing.Timer;

public class Foo implements WindowListener {

    private Timer timer;

    public static void main(String args[]){
       initTimerComponent();
    }

    private void initTimerComponent() {
      int delay = 1000;           //milliseconds    

      timer = new Timer(delay, null);
      timer.addActionListener(new ActionListener() {
          public void actionPerformed(ActionEvent evt) {
            tempLabel.setVisible(true);
            String tmp = "test";                           
            tempLabel.setText("Temperature :  " + tmp);   
          }
      });

      timer.start();  
    }

    @Override
    public void windowOpened(WindowEvent e) { }

    @Override
    public void windowClosing(WindowEvent e) {
       timer.stop();
    }

    @Override
    public void windowClosed(WindowEvent e) { }

    @Override
    public void windowIconified(WindowEvent e) { }

    @Override
    public void windowDeiconified(WindowEvent e) { }

    @Override
    public void windowActivated(WindowEvent e) { }

    @Override
    public void windowDeactivated(WindowEvent e) { }
}

您必须全部实现它们，因为WindowListener是一个接口，并且实现接口的第一个具体类被强制实现其所有抽象方法。但实际上你只需要一种方法。

使用此方法

public void windowClosing(WindowEvent e) {
   timer.stop();
}

在用户点击红色X后，在窗口关闭后立即停止计时器。

Answer 2

回答

addWindowListener(new WindowAdapter() {
        //for closing
        @Override
        public void windowClosing(WindowEvent e) {
            JOptionPane.showMessageDialog(null, "Closing");
        }
        //for closed

        @Override
        public void windowClosed(WindowEvent e) {
        }
    });

Java - 如何检查JFrame是否已关闭

2 个答案: