Java Thread holdLock()方法

如果當前線程在指定對象上保存監視器鎖，則Thread類的holdLock()方法返回true。

語法

public static boolean holdsLock(Object obj)

參數

• obj：它定義了測試鎖所有權的對象

返回
當且僅當當前線程在指定對象上保存監視器鎖時，它才返回true。 否則，它返回false。

示例

• NullPointerException：如果obj為null，則拋出此異常。

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();
    }
}

執行上面示例代碼，得到以下結果：

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