一、等待与通知

public class AnimatedCharacterDisplayCanvas extends CharacterDisplayCanvas implements CharacterListener, Runnable {

    private boolean done = true;
    private int curX = 0;
    private Thread timer = null;

    public AnimatedCharacterDisplayCanvas() {
    }

    public AnimatedCharacterDisplayCanvas(CharacterSource cs) {
        super(cs);
    }

    public synchronized void newCharacter(CharacterEvent ce) {
        curX = 0;
        tmpChar[0] = (char) ce.character;
        repaint();
    }

    protected synchronized void paintComponent(Graphics gc) {
        Dimension d = getSize();
        gc.clearRect(0, 0, d.width, d.height);
        if (tmpChar[0] == 0)
            return;
        int charWidth = fm.charWidth(tmpChar[0]);
        gc.drawChars(tmpChar, 0, 1,
                     curX++, fontHeight);
    }

    public synchronized void run() {
        while (true) {
            try {
                if (done) {
                    wait();
                } else {
                    repaint();
                    wait(100);
                }
            } catch (InterruptedException ie) {
                return;
            }
        }
    }

    public synchronized void setDone(boolean b) {
        done = b;

        if (timer == null) {
            timer = new Thread(this);
            timer.start();
        }
        if (!done)
            notify();
    }
 }

public class AnimatedCharacterDisplayCanvas extends CharacterDisplayCanvas implements CharacterListener, Runnable {

    private boolean done = true;
    private int curX = 0;
    private Thread timer = null;
    private Object doneLock = new Object();

    public AnimatedCharacterDisplayCanvas() {
    }

    public AnimatedCharacterDisplayCanvas(CharacterSource cs) {
        super(cs);
    }

    public synchronized void newCharacter(CharacterEvent ce) {
        curX = 0;
        tmpChar[0] = (char) ce.character;
        repaint();
    }

    protected synchronized void paintComponent(Graphics gc) {
        Dimension d = getSize();
        gc.clearRect(0, 0, d.width, d.height);
        if (tmpChar[0] == 0)
            return;
        int charWidth = fm.charWidth(tmpChar[0]);
        gc.drawChars(tmpChar, 0, 1,
                     curX++, fontHeight);
    }

    public void run() {
	synchronized(doneLock) {
            while (true) {
                try {
                    if (done) {
                        doneLock.wait();
                    } else {
                        repaint();
                        doneLock.wait(100);
                    }
                } catch (InterruptedException ie) {
                    return;
                }
            }
	}
    }

    public void setDone(boolean b) {
	synchronized(doneLock) {
            done = b;

            if (timer == null) {
                timer = new Thread(this);
                timer.start();
            }
            if (!done)
                doneLock.notify();
	}
    }
 }

二、条件变量

public class RandomCharacterGenerator extends Thread implements CharacterSource {
    private static char[] chars;
    private static String charArray = "abcdefghijklmnopqrstuvwxyz0123456789";
    static {
        chars = charArray.toCharArray();
    }

    private Random random;
    private CharacterEventHandler handler;
    private boolean done = true;
    private Lock lock = new ReentrantLock();
    private Condition cv = lock.newCondition();

    public RandomCharacterGenerator() {
        random = new Random();
        handler = new CharacterEventHandler();
    }

    public int getPauseTime() {
        return (int) (Math.max(1000, 5000 * random.nextDouble()));
    }

    public void addCharacterListener(CharacterListener cl) {
        handler.addCharacterListener(cl);
    }

    public void removeCharacterListener(CharacterListener cl) {
        handler.removeCharacterListener(cl);
    }

    public void nextCharacter() {
        handler.fireNewCharacter(this,
                                (int) chars[random.nextInt(chars.length)]);
    }

    public void run() {
        try {
            lock.lock();
            while (true) {
                try {
                    if (done) {
                        cv.await();
                    } else {
                        nextCharacter();
                        cv.await(getPauseTime(), TimeUnit.MILLISECONDS);
                    }
                } catch (InterruptedException ie) {
                    return;
                }
            }
        } finally {
            lock.unlock();
        }
    }

    public void setDone(boolean b) {
        try {
            lock.lock();
            done = b;

            if (!done) cv.signal();
        } finally {
            lock.unlock();
        }
    }
}