问一道线程同步面试题

Question

面试题thread线程

Answer 1

 ⑴处        Thread t=new Thread(inc);          这个线程直接用   函数inc做参数是什么意思？
      Thread构造函数定义：
       public Thread(Runnable target) {
        init(null, target, "Thread-" + nextThreadNum(), 0);
    }
class Inc implements Runnable
  Inc实现了Runnable接口，此处作为target，告知新产生的Thread到底执行哪个target的run函数   ⑵处      for(int i=0;i<100;i++)       这个循环的目的是什么？
        这里循环一百次的目的是为了控制每个线程执行的时间。
      如果改为 for(int i=0;i<10;i++)（方便展示），输出结果：
第一次：
      Thread-0-inc:1
Thread-0-inc:2
Thread-0-inc:3
Thread-0-inc:4
Thread-0-inc:5
Thread-0-inc:6
Thread-0-inc:7
Thread-0-inc:8
Thread-0-inc:9
Thread-0-inc:10
Thread-3-dec:9
Thread-3-dec:8
Thread-3-dec:7
Thread-3-dec:6
Thread-3-dec:5
Thread-3-dec:4
Thread-3-dec:3
Thread-3-dec:2
Thread-3-dec:1
Thread-3-dec:0
Thread-1-dec:-1
Thread-1-dec:-2
Thread-1-dec:-3
Thread-1-dec:-4
Thread-1-dec:-5
Thread-1-dec:-6
Thread-1-dec:-7
Thread-1-dec:-8
Thread-1-dec:-9
Thread-1-dec:-10
Thread-2-inc:-9
Thread-2-inc:-8
Thread-2-inc:-7
Thread-2-inc:-6
Thread-2-inc:-5
Thread-2-inc:-4
Thread-2-inc:-3
Thread-2-inc:-2
Thread-2-inc:-1
Thread-2-inc:0（两次增的过程，两次减的过程）
第二次：
Thread-0-inc:1
Thread-0-inc:2
Thread-0-inc:3
Thread-1-dec:2
Thread-3-dec:1
Thread-3-dec:0
Thread-3-dec:-1
Thread-3-dec:-2
Thread-3-dec:-3
Thread-3-dec:-4
Thread-3-dec:-5
Thread-3-dec:-6
Thread-3-dec:-7
Thread-3-dec:-8
Thread-0-inc:-7
Thread-0-inc:-6
Thread-0-inc:-5
Thread-0-inc:-4
Thread-0-inc:-3
Thread-0-inc:-2
Thread-0-inc:-1
Thread-1-dec:-2
Thread-1-dec:-3
Thread-1-dec:-4
Thread-1-dec:-5
Thread-1-dec:-6
Thread-1-dec:-7
Thread-1-dec:-8
Thread-1-dec:-9
Thread-1-dec:-10
Thread-2-inc:-9
Thread-2-inc:-8
Thread-2-inc:-7
Thread-2-inc:-6
Thread-2-inc:-5
Thread-2-inc:-4
Thread-2-inc:-3
Thread-2-inc:-2
Thread-2-inc:-1
Thread-2-inc:0（三次增，两次减）所以这个地方加循环主要是为了增加线程循环体的时间，从而可以体现出不同线程对共同资源的操作的特点