i++操作非原子的验证代码

package incre;

public class Incre {
    public static void main(String[] args) {
        class Count implements Runnable {
            public int num;
            @Override
            public void run() {
                //自增操作，非原子操作，线程不安全
//                for (int i = 0; i < 10000; i++) {
//                    num++;
//                }

                //对代码进行同步，查看正确结果。
                synchronized (this) {
                    for (int i = 0; i < 10000; i++) {
                        num++;
                    }
                }
            }

            public int getNum(){
                return num;
            }
        }

        Count c = new Count();

        //创建多个线程
        final int THREAD_COUNT = 10;
        Thread[] threadArray = new Thread[THREAD_COUNT];
        for(int i = 0; i < threadArray.length; i++){
            threadArray[i] = new Thread(c);
        }

        //启动多个线程
        for(Thread t : threadArray){
            t.start();
        }

        //等待这些线程结束
        for(Thread t : threadArray){
            try {
                t.join();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }

        //查看计数结果
        System.out.println("计数结果：" + c.getNum());
    }
}