java synchronized 同步问题

Question

请问通过下面这种方法能起到防止haha()和run()中的synchronized中的内容同时执行的作用吗？

 public class A{
     public synchronized void haha(){

     }
     class B extends TimerTask{
        @Override
        public void run(){
            synchronized(A.this){

            }
        }
     }
 }

Answer 1

 public class A{
  int value = 0;

  final int NUMBER = 1000000;

    public synchronized void haha(){
        for (int i = 0; i < NUMBER; i++)
            value ++;
  }

  class B extends TimerTask{
     @Override
     public void run(){
         synchronized(A.this){
            for (int i = 0; i < NUMBER; i++)
                value ++;
         }
     }
  }

  public static void main(String args[]) throws InterruptedException {
    A a = new A();
    B b = a.new B();

    ScheduledThreadPoolExecutor executor = new ScheduledThreadPoolExecutor(2);

    executor.scheduleWithFixedDelay(b, 1, 1, TimeUnit.SECONDS);
    executor.scheduleWithFixedDelay(new Runnable() {

            @Override
            public void run() {
                a.haha();
            }

    }, 1, 1, TimeUnit.SECONDS);

    Thread.sleep(1000 * 9 + 500);

    executor.shutdownNow();

    System.out.printf("value: %d\n", a.value);  
  }

}