一个简单的多线程同步例子

/** * Created by pengyi on 2015/3/30 0030. */public class Hello implements Runnable {    private Integer amount = 50;    private String s = "-";    boolean a = true;    public void run() {        if ("线程一".equals(Thread.currentThread().getName()) ||                "线程二".equals(Thread.currentThread().getName()) ||                "线程三".equals(Thread.currentThread().getName()) ||                "线程四".equals(Thread.currentThread().getName()) ||                "线程五".equals(Thread.currentThread().getName()) ||                "线程11".equals(Thread.currentThread().getName()) ||                "线程12".equals(Thread.currentThread().getName()) ||                "线程13".equals(Thread.currentThread().getName()) ||                "线程14".equals(Thread.currentThread().getName()) ||                "线程15".equals(Thread.currentThread().getName()) ||                "线程21".equals(Thread.currentThread().getName()) ||                "线程22".equals(Thread.currentThread().getName()) ||                "线程23".equals(Thread.currentThread().getName()) ||                "线程24".equals(Thread.currentThread().getName()) ||                "线程25".equals(Thread.currentThread().getName()) ||                "线程31".equals(Thread.currentThread().getName()) ||                "线程32".equals(Thread.currentThread().getName()) ||                "线程33".equals(Thread.currentThread().getName()) ||                "线程34".equals(Thread.currentThread().getName()) ||                "线程35".equals(Thread.currentThread().getName()) ||                "线程41".equals(Thread.currentThread().getName()) ||                "线程42".equals(Thread.currentThread().getName()) ||                "线程43".equals(Thread.currentThread().getName()) ||                "线程44".equals(Thread.currentThread().getName()) ||                "线程45".equals(Thread.currentThread().getName())) {            while (0 < amount) {                if (a) {                    a = false;                    synchronized (this) {                        amount = (amount - 1);                        System.out.println(amount + "<---------->" + Thread.currentThread().getName());                    }                    try {                        Thread.sleep(200);                    } catch (InterruptedException e) {                        System.out.println(e.getMessage());                    }                } else {                    try {                        synchronized (this) {                            super.wait();                        }                    } catch (InterruptedException e) {                        e.printStackTrace();                    }                }                a = true;                synchronized (this) {                    super.notify();                }            }        }else {            while (100 > amount) {                if (a) {                    a = false;                    synchronized (this) {                        amount = (amount + 1);                        System.out.println(amount + "<---------->" + Thread.currentThread().getName());                    }                    try {                        Thread.sleep(200);                    } catch (InterruptedException e) {                        System.out.println(e.getMessage());                    }                } else {                    try {                        synchronized (this) {                            super.wait();                        }                    } catch (InterruptedException e) {                        e.printStackTrace();                    }                }                a = true;                synchronized (this) {                    super.notify();                }            }        }    }    public static void main(String[] args) {        Hello he = new Hello();        Thread thread1 = new Thread(he, "线程一");        thread1.start();        Thread thread2 = new Thread(he, "线程二");        thread2.start();        Thread thread3 = new Thread(he, "线程三");        thread3.start();        Thread thread4 = new Thread(he, "线程四");        thread4.start();        Thread thread5 = new Thread(he, "线程五");        thread5.start();        Thread thread6 = new Thread(he, "线程六");        thread6.start();        Thread thread7 = new Thread(he, "线程七");        thread7.start();        Thread thread8 = new Thread(he, "线程八");        thread8.start();        Thread thread9 = new Thread(he, "线程九");        thread9.start();        Thread thread10 = new Thread(he, "线程十");        thread10.start();        Thread thread11 = new Thread(he, "线程11");        thread11.start();        Thread thread12 = new Thread(he, "线程12");        thread12.start();        Thread thread13 = new Thread(he, "线程13");        thread13.start();        Thread thread14 = new Thread(he, "线程14");        thread14.start();        Thread thread15 = new Thread(he, "线程15");        thread15.start();        Thread thread16 = new Thread(he, "线程16");        thread16.start();        Thread thread17 = new Thread(he, "线程17");        thread17.start();        Thread thread18 = new Thread(he, "线程18");        thread18.start();        Thread thread19 = new Thread(he, "线程19");        thread19.start();        Thread thread20 = new Thread(he, "线程20");        thread20.start();        Thread thread21 = new Thread(he, "线程21");        thread21.start();        Thread thread22 = new Thread(he, "线程22");        thread22.start();        Thread thread23 = new Thread(he, "线程23");        thread23.start();        Thread thread24 = new Thread(he, "线程24");        thread24.start();        Thread thread25 = new Thread(he, "线程25");        thread25.start();        Thread thread26 = new Thread(he, "线程26");        thread26.start();        Thread thread27 = new Thread(he, "线程27");        thread27.start();        Thread thread28 = new Thread(he, "线程28");        thread28.start();        Thread thread29 = new Thread(he, "线程29");        thread29.start();        Thread thread30 = new Thread(he, "线程30");        thread30.start();        Thread thread31 = new Thread(he, "线程31");        thread31.start();        Thread thread32 = new Thread(he, "线程32");        thread32.start();        Thread thread33 = new Thread(he, "线程33");        thread33.start();        Thread thread34 = new Thread(he, "线程34");        thread34.start();        Thread thread35 = new Thread(he, "线程35");        thread35.start();        Thread thread36 = new Thread(he, "线程36");        thread36.start();        Thread thread37 = new Thread(he, "线程37");        thread37.start();        Thread thread38 = new Thread(he, "线程38");        thread38.start();        Thread thread39 = new Thread(he, "线程39");        thread39.start();        Thread thread40 = new Thread(he, "线程40");        thread40.start();        Thread thread41 = new Thread(he, "线程41");        thread41.start();        Thread thread42 = new Thread(he, "线程42");        thread42.start();        Thread thread43 = new Thread(he, "线程43");        thread43.start();        Thread thread44 = new Thread(he, "线程44");        thread44.start();        Thread thread45 = new Thread(he, "线程45");        thread45.start();        Thread thread46 = new Thread(he, "线程46");        thread46.start();        Thread thread47 = new Thread(he, "线程47");        thread47.start();        Thread thread48 = new Thread(he, "线程48");        thread48.start();        Thread thread49 = new Thread(he, "线程49");        thread49.start();        Thread thread50 = new Thread(he, "线程50");        thread50.start();    }}//开了50个线程，25个线程是+1，25个是-1，所以理论上是死循环