java - 多线程程序输出不符合预期

Question

多线程

public class RaceData {

public static void main(String[] args) {

    class UnsafeSequence implements Runnable{
        private int value = 0;

        /** Returns a unique value. */

        public void run(){

            synchronized (this) {
                value = value +1;
                System.out.printf("Thread %s and Count value is %d \n",Thread.currentThread().getName(),value);
            }
        }
    }

    UnsafeSequence s = new UnsafeSequence();
    Thread t1 = new Thread(s);
    t1.setName("t1");
    t1.start();
    Thread t2 = new Thread(s);
    t2.setName("t2");
    t2.start();
    Thread t3 = new Thread(s);
    t3.setName("t3");
    t3.start();
    Thread t4 = new Thread(s);
    t4.setName("t4");
    t4.start();
    Thread t5 = new Thread(s);
    t5.setName("t5");
    t5.start();     
}
}

输出是:

Thread t1 and Count value is 1 
Thread t5 and Count value is 2 
Thread t3 and Count value is 3 
Thread t4 and Count value is 4 
Thread t2 and Count value is 5 

为什么计数值没有正确显示？抱歉，我正在修改我的问题，它与计数变量值无关，我预计线程 t2 在 t1 之后执行，因为我在 t1 之后启动了 t2，尽管我一个接一个地启动了线程，但这里的线程并未按顺序执行。

Answer 1

计数正确显示。每次线程访问 synchronized block 时，count 都会递增。

您不能期望线程按照启动的顺序访问synchronized block 。