执行如下程序, 输出结果是()

class Test {
	private int data;
	int result = 0;
	public void m() {
		result += 2;
		data += 2;
	System.out.print(result + " " + data);
	}
}
class ThreadExample extends Thread {
	private Test mv;
	public ThreadExample(Test mv)  {
	this.mv = mv;
	}
	public void run() {
		synchronized(mv){
			mv.m();
		}
	}
}
class ThreadTest {
	public static void main(String args[]) {
		Test mv = new Test();	// 声明并初始化对data赋默认值 
		Thread t1 = new ThreadExample(mv);
		Thread t2 = new ThreadExample(mv);
		Thread t3 = new ThreadExample(mv);
		t1.start();
		t2.start();
		t3.start();
	}
}

A. 0 22 44 6

B. 2 42 42 4

C.2 24 46 6

D. 4 44 46 6

解析: 

1. 使用synchronized关键字加同步锁, 使三个线程一次顺序操作m()方法
2. t1.start();     使得result = 2; data = 2
3. t2.start();     使得result = 4; data = 4;
4. t3.start():     使得result = 6; data = 6;
5. System.out.print(result+” “+data);  print方法, 不会自动换行, 所以输出结果是2 24 46 6