尋找使用thread.sleep暫停線程

Question

我正在使用鼠標偵聽器來按下和釋放鼠標。 按下鼠標時，我想讓計數器增加一個變量，釋放鼠標時，我要減少該變量。 現在，我的代碼可以正常工作，但是這樣做的速度太快了，我想減慢速度，因為我將這些數字用作游戲中的坐標。 我嘗試添加Thread.sleep（100），但是輸出偏斜。 似乎有多個線程同時出現，並且到處都是數字。 下面是示例代碼。

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JButton;
import java.awt.event.*;
import java.awt.event.ActionListener;
import java.lang.*;

public class Sample extends JFrame {
    private JPanel jp = new JPanel();

    int i = 0;
    boolean once = true;
    boolean on = true;

    Thread t1 = new Thread(new Increase());
    Thread t2 = new Thread(new Decrease());

    public sample() {
        setVisible(true);
        setSize(300, 300);
        setDefaultCloseOperation(EXIT_ON_CLOSE);

        add(jp);

        addMouseListener(new MouseAdapter() {
            public void mousePressed(MouseEvent event) {
                if (!once) //false
                {
                    t2.interrupt();
                }

                if (once) //true
                {
                    once = false;
                    t1.start();
                }
                else {
                    t1 = new Thread(new Increase());
                    t1.start();
                }
            }

            public void mouseReleased(MouseEvent event) {
                t1.interrupt();
                if (on) //true
                {
                    on = false;
                    t2.start();
                }
                else {
                    t2 = new Thread(new Decrease());
                    t2.start();
                }
            }
        });
    }

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

    public int getI() {
        return i;
    }

    public void setI(int num) {
        i = num;
    }

    class Increase implements Runnable {
        public void run() {
            int num = getI();
            while (!Thread.currentThread().isInterrupted()) {
                try {
                    setI(++num);
                    Thread.sleep(100);
                    System.out.println(num);
                }
                catch (InterruptedException e) {
                }
            }
        }
    }

    //Thread.currentThread().isInterrupted()
    class Decrease implements Runnable {
        public void run() {
            int num = getI();
            while (!Thread.currentThread().isInterrupted()) {
                try {
                    setI(--num);
                    Thread.sleep(100);
                    System.out.println(num);
                }
                catch (InterruptedException e) {
                }
            }
        }
    }
}

Answer 1

你可能運行到兩個線程之間的競爭條件，事實上， i是不揮發也表明線程可能不相同的實際值相互合作。

線程也是不可重入的，這意味着一旦存在run方法，就無法重新啟動它們。

您只需使用一個Thread和一個“增量”（或更改）值即可達到相同的結果。

以下示例使用了Swing Timer ，因為它更簡單，並且允許我安全地更新UI，但是原理是相同的。

import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class Test {

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

    public Test() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                    ex.printStackTrace();
                }

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.add(new TestPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel {

        private JLabel label;
        private Timer timer;
        private int value = 0;
        private int delta = 1;

        public TestPane() {
            setLayout(new GridBagLayout());
            label = new JLabel("0");
            add(label);
            addMouseListener(new MouseAdapter() {

                @Override
                public void mousePressed(MouseEvent e) {
                    delta *= -1;
                }

                @Override
                public void mouseReleased(MouseEvent e) {
                    delta *= -1;
                }

            });

            timer = new Timer(100, new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    setValue(getValue() + delta);
                }
            });
            timer.start();
        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(200, 200);
        }

        public int getValue() {
            return value;
        }

        public void setValue(int value) {
            this.value = value;
            label.setText(Integer.toString(value));
        }

    }

}

更新了雙“線程”

只是因為我完全瘋了，很高興演示額外的工作量。 本示例使用兩個Thread 。

import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class Test {

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

    public Test() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                    ex.printStackTrace();
                }

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.add(new TestPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel implements Value {

        private JLabel label;
        private volatile int value = 0;

        private ManipulateRunner incrementRunner;
        private ManipulateRunner decrementRunner;

        private Thread incrementThread;
        private Thread decrementThread;

        public TestPane() {

            incrementRunner = new ManipulateRunner(this, 1);
            decrementRunner = new ManipulateRunner(this, -1);

            setLayout(new GridBagLayout());
            label = new JLabel("0");
            add(label);
            addMouseListener(new MouseAdapter() {

                @Override
                public void mousePressed(MouseEvent e) {

                    decrementRunner.pause();
                    if (incrementThread == null) {
                        incrementThread = new Thread(incrementRunner);
                        incrementThread.start();
                    }

                    incrementRunner.resume();

                }

                @Override
                public void mouseReleased(MouseEvent e) {

                    incrementRunner.pause();
                    if (decrementThread == null) {
                        decrementThread = new Thread(decrementRunner);
                        decrementThread.start();
                    }

                    decrementRunner.resume();

                }

            });
        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(200, 200);
        }

        @Override
        public int getValue() {
            return value;
        }

        @Override
        public void setValue(final int value) {
            if (EventQueue.isDispatchThread()) {
                this.value = value;
                label.setText(Integer.toString(value));
            } else {
                SwingUtilities.invokeLater(new Runnable() {
                    @Override
                    public void run() {
                        setValue(value);
                    }
                });
            }
        }

    }

    public static interface Value {

        public int getValue();

        public void setValue(int value);
    }

    public static class ManipulateRunner implements Runnable {

        protected final Object pauseLock = new Object();
        private int delta;
        private AtomicBoolean paused = new AtomicBoolean(false);
        private AtomicBoolean stopped = new AtomicBoolean(false);
        private Value value;

        public ManipulateRunner(Value value, int delta) {
            this.delta = delta;
            this.value = value;
        }

        public void pause() {

            if (!paused.get() && !stopped.get()) {

                paused.set(true);
                synchronized (pauseLock) {
                    pauseLock.notify();
                }

            }

        }

        public void resume() {

            if (paused.get() && !stopped.get()) {

                paused.set(false);
                synchronized (pauseLock) {
                    pauseLock.notify();
                }

            }

        }

        public void stop() {

            if (!stopped.get()) {

                stopped.set(true);
                synchronized (pauseLock) {
                    pauseLock.notify();
                }

            }

        }

        @Override
        public void run() {

            while (!stopped.get()) {

                while (!stopped.get() && paused.get()) {
                    synchronized (pauseLock) {
                        try {
                            pauseLock.wait();
                        } catch (InterruptedException ex) {
                        }
                    }
                }

                if (!stopped.get()) {
                    value.setValue(value.getValue() + delta);

                    try {
                        Thread.sleep(100);
                    } catch (InterruptedException ex) {
                    }
                }

            }

        }

    }

}

就個人而言，最簡單有效的解決方案是更好的解決方案，但這就是我