当我想要线程时，线程不会停止吗？（Java）

Question

我的屏幕录制应用程序中有一个线程无法配合：

package recorder;

import java.awt.AWTException;
import java.awt.Insets;
import java.io.IOException;

import javax.swing.JFrame;

public class RepeatThread extends Thread {
    volatile boolean stop;
    public volatile Thread recordingThread;
    JFrame frame;
    int count = 0;

    RepeatThread( JFrame myFrame ) {
        stop = false;
        frame = myFrame;
    }

    public void run() {
        while( stop == false ) {
            int loopDelay = 33; // 33 is approx. 1000/30, or 30 fps
            long loopStartTime = System.currentTimeMillis();
            Insets insets = frame.getInsets(); // Get the shape we're recording

            try {
                ScreenRecorder.capture( frame.getX() + insets.left, 
                        frame.getY() + insets.top, frame.getWidth()
                        - ( insets.left + insets.right ), 
                        frame.getHeight() - ( insets.top + insets.bottom ) );
            }
            catch( AWTException e1 ) {
                // TODO Auto-generated catch block
                e1.printStackTrace();
            }
            catch( IOException e1 ) {
                // TODO Auto-generated catch block
                e1.printStackTrace();
            } // Add another picture

            long loopEndTime = System.currentTimeMillis();
            int loopTime = (int )( loopEndTime - loopStartTime );
            if( loopTime < loopDelay ) {
                try {
                    sleep( loopDelay - loopTime ); // If we have extra time,
                                                   // sleep
                }
                catch( Exception e ) {
                } // If something interrupts it, I don't give a crap; just
                  // ignore it
            }
        }

    }

    public void endThread() {
        stop = true;
        count = 0;
        ScreenRecorder.reset();
        // Once I get this annoying thread to work, I have to make the pictures
        // into a video here!
    }
}

多年来一直困扰着我。它会定期将屏幕截图带到指定区域。

当您开始录制时，它会隐藏（缩小）窗口。在Mac上，当您以应用程序为焦点时，所有隐藏的窗口都会激活。在我的课程中WListener（我已经确认可以工作），我有：

    public void windowActivated（WindowEvent e）{
        if（ScreenRecorder.recordingThread！= null）{
            ScreenRecorder.recordingThread.endThread（）;
        }
    }

所以应该发生的是，当他单击应用程序时，截屏线程将停止。但是，我必须残酷地搞砸一些东西，因为当线程运行时，它甚至不会让窗口重新出现。这是我的第一个话题，所以我期待这样的怪异问题。你知道怎么了吗

编辑：好的，我使stop变为volatile，这是我创建线程的地方：

package recorder;

import java.awt.AWTException;
import java.awt.Robot;
import java.awt.Rectangle;
import java.awt.image.BufferedImage;
import java.io.*;
import javax.imageio.ImageIO;
import javax.swing.JFrame;

public class ScreenRecorder {

    static RepeatThread recordingThread;
    static int count;

    public static void record(JFrame frame) {

        if(recordingThread == null) { //Make a new thread if we don't have one
            recordingThread = new RepeatThread(frame);
            recordingThread.start();
        }
    }

    public static void capture(int x, int y, int width, int height) throws AWTException, IOException {
        // capture the whole screen
        //BufferedImage screencapture = new Robot().createScreenCapture(
        //      new Rectangle(Toolkit.getDefaultToolkit().getScreenSize()) );

        BufferedImage screencapture = new Robot().createScreenCapture(
                new Rectangle( x, y, width, height));

        // Save as JPEG
        File directory = new File("/Users/stuart/Movies/temp");
        if(directory.exists() == false) {
            directory.mkdirs();
        }

        count ++;
        File file = new File("/Users/stuart/Movies/temp/screencapture" + count + ".jpg");
        ImageIO.write(screencapture, "jpg", file);


        // Save as PNG
        // File file = new File("screencapture.png");
        // ImageIO.write(screencapture, "png", file);

    }

    public static void stop() {

    }

    public static void reset() {
        count = 0;
    }
}

Answer 1

因为您显然试图每X毫秒执行一个工作单元，所以如果使用Java的Executor，这将容易得多：

ScheduledExecutorService service = executors.newSingleThreadScheduledExecutor();
service.scheduleAtFixedRate(new Runnable() {
  public void run() {
    // do one iteration of your work
    ScreenRecorder.capture(...);
    ...
  }
}, 0L, 33L, TimeUnit.MILLISECONDS);

...
service.shutdown(); // to stop

手动执行操作并Thread没有您做的那么麻烦（不是在挖洞，只是说在Java中并不那么糟糕），但是以上内容仍然是最简单的选择。