我想兩個線程共享的變量,但有時在運行時它打印出2次,而不是1和2線程共享實例變量
public class man implements Runnable{
int value = 0;
public static void main(String[] args){
Runnable job = new man();
Thread work1 = new Thread(job);
work1.setName("Thread1");
Thread work2 = new Thread(job);
work2.setName("Thread2");
work1.start();
work2.start();
}
public void run(){
synchronized(this){
value = value + 1;
}
System.out.println("VALUE = " + value +", Running " + Thread.currentThread().getName());
}
}
輸出有時是:
VALUE = 2, Running Thread2
VALUE = 2, Running Thread1
等次是:
VALUE = 1, Running Thread2
VALUE = 2, Running Thread1
這究竟是爲什麼?我在HeadFirst的書中學習Java,這個問題出現了。
哦,不錯,謝謝你的提示。 –