Java Thread holdLock()方法

如果当前线程在指定对象上保存监视器锁，则Thread类的holdLock()方法返回true。

语法

public static boolean holdsLock(Object obj)

参数

• obj：它定义了测试锁所有权的对象

返回
当且仅当当前线程在指定对象上保存监视器锁时，它才返回true。 否则，它返回false。

示例

• NullPointerException：如果obj为null，则抛出此异常。

示例

public class JavaHoldLockExp implements Runnable   
{  
    public void run()   
    {  
        // print currently executing thread   
        System.out.println("Currently executing thread is: " + Thread.currentThread().getName());  
        // returns true if the current thread holds the lock on the specified object   
        System.out.println("Does thread holds lock? " + Thread.holdsLock(this));  
        synchronized (this)   
        {  
            System.out.println("Does thread holds lock? " + Thread.holdsLock(this));  
        }  
    }  
    public static void main(String[] args)   
    {  
        JavaHoldLockExp g1 = new JavaHoldLockExp();  
        // create a thread  
        Thread t1 = new Thread(g1);  
        // this will call run() function  
        t1.start();  
    }  
}

执行上面示例代码，得到以下结果：

Currently executing thread is: Thread-0
Does thread holds lock? false
Does thread holds lock? true