thread

package thread;

public class ThreadIncDec {

	private int j;

	public static void main(String[] args) {
		/*
		 * 如果用下面的代码，inc(),dec()两个方法要加synchronized,锁的是这个方法所在的对象incDec.
		 */
//		ThreadIncDec incDec = new ThreadIncDec();
//		Inc inc = incDec.new Inc();
//		Dec dec = incDec.new Dec();
//		for (int i = 0; i < 1; i++) {
//			Thread t = new Thread(inc);
//			t.start();
//			t = new Thread(dec);
//			t.start();
//		}
		/*
		 * 如果用下面的代码，inc(),dec()两个方法就不需要加synchronized,两个对象
		 */
		ThreadIncDec incDec = new ThreadIncDec();
		ThreadIncDec incDec1 = new ThreadIncDec();
		Inc inc = incDec.new Inc();
		Dec dec = incDec1.new Dec();
		for (int i = 0; i < 2; i++) {//如果这里用四个线程(i<2)，不加syncrhronized就有问题（没有锁定方法入口，可能有别的线程进入inc().Thread-1-inc:2
	//		Thread-0-inc:2)
			Thread t = new Thread(inc);
			t.start();
//			t = new Thread(dec);
//			t.start();
		}
		
	}
	
	//计数加一
	private  void inc() {
		j++;
//		try {
//			Thread.sleep(10);
//		} catch (InterruptedException e) {
//			// TODO Auto-generated catch block
//			e.printStackTrace();
//		}
		System.out.println(Thread.currentThread().getName() + "-inc:" + j);
	}

	//计数减一
	private  void dec() {
		j--;
		System.out.println(Thread.currentThread().getName() + "-dec:" + j);
	}

	//内部类实现的线程，线程对计数器加一
	class Inc implements Runnable {
		public void run() {
			for (int i = 0; i < 100; i++) {
				inc();
			}
		}
	}

	//内部类实现的线程，线程对计数器减一
	class Dec implements Runnable {
		public void run() {
			for (int i = 0; i < 10; i++) {
				dec();
			}
		}
	}
}

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