Java问题：
退出同步块会自动执行 notifyAll()。这是预期的行为吗？
我已经对其进行了测试，它看起来像 1. 当执行超出同步块时，它会自动 notifyAll() 2. 当方法本身同步时，它会在返回时自动 notify()。（不是 notifyAll()）
代码 ：
public class Test {
public static void main(String[] args) throws InterruptedException {
MyThread lock = new MyThread();
new WatingThread(lock,1).start();
new WatingThread(lock,2).start();
//above tow threads would start and then wait for a lock
lock.start();
}
}
class MyThread extends Thread {
public void run() {
try {
Thread.sleep(2000);
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println("MyThread is trying to acquire the lock ..");
synchronized (this) {
System.out.println("MyThread has acquired the lock !!");
System.out.println("MyThread is Coming out of synch block..");
}
System.out.println("MyThread has released the lock !!");
}
}
class WatingThread extends Thread
{
private Object lock;
private int id;
public WatingThread(Object lock, int id )
{
this.lock = lock;
this.id = id;
}
@Override
public void run() {
System.out.println(String.format("[%d] : Check if lock is available ...",new Object[]{id}));
synchronized (lock) {
System.out.println(String.format("[%d] : Acquired the lock !!",new Object[]{id}));
try {
System.out.println(String.format("[%d] : Going to wait on lock.. ",new Object[]{id}));
lock.wait();
System.out.println(String.format("[%d] : Got notified !!!",new Object[]{id}));
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println(String.format("[%d] :I am done !!",new Object[]{id}));
}
}
}
输出：
[2]：检查锁是否可用...
[2]：获得锁！
[1] : 检查锁是否可用...
[2] : 等待锁..
[1] : 获得锁！！
[1] : 正在等待锁..
MyThread 正在尝试获取锁..
MyThread 已获取锁！
MyThread 正在脱离同步块..
MyThread 已释放锁定！
[1]：收到通知！！！
[1]：我完成了！
[2]：收到通知！！！
[2]：我完成了！