Java Thread holdLock()方法

如果當前執行緒在指定物件上儲存監視器鎖，則Thread類的holdLock()方法返回true。

語法

public static boolean holdsLock(Object obj)

引數

• obj：它定義了測試鎖所有權的物件

返回
當且僅當當前執行緒在指定物件上儲存監視器鎖時，它才返回true。 否則，它返回false。

範例

• NullPointerException：如果obj為null，則丟擲此異常。

範例

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();  
    }  
}

執行上面範例程式碼，得到以下結果：

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