Question

我正在使用java8＆amp;我编写了一个程序来识别java中Threads的'Synchronized（）'的行为。这些是我创建的类和＆amp;我得到了意想不到的输出。

public class PrintNumberDemo {

public void printNumbers() {
    for(int i=0;i<=20;i++) {
        System.out.println(i);
    }
}

}

public class PrintStarDemo {
public void printStars() {
    for(int i=0;i<=20;i++) {
        System.out.println("*");
    }
}

}

public class PrintThread implements Runnable {

Thread t;
String name;
PrintNumberDemo pd;
PrintStarDemo ps;

PrintThread(Object ob, String name) {
    if (ob instanceof PrintNumberDemo) {
        this.pd = (PrintNumberDemo) ob;
    }
    if (ob instanceof PrintStarDemo) {
        this.ps = (PrintStarDemo) ob;
    }
    this.name = name;
}

@Override
public void run() {
    // TODO Auto-generated method stub
    if (pd != null)
        synchronized (pd) {
            pd.printNumbers();
        }
    if (ps != null)
        synchronized (ps) {
            ps.printStars();
        }

}

public void start() {
    if (t == null) {
        t = new Thread(this, name);
        System.out.println("Starting " + name);
        t.start();
    }

}

}

public class TestPrintDemo {

public static void main(String[] args) {

    PrintNumberDemo pd1= new PrintNumberDemo();
    PrintStarDemo ps1 = new PrintStarDemo();

    PrintThread t1 = new PrintThread(pd1,"Thread-01");      
    PrintThread t2 = new PrintThread(ps1,"Thread-02");
    t1.start();
    t2.start();
}

}

输出：

Starting Thread-01 Starting Thread-02 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
* 17 18 19 20

任何人都可以解释，为什么它会显示出这样的输出？

在我的多线程类中，Synchronized无法正常工作

0 个答案: