Java.lang.Thread.holdsLock() Method

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Description

The java.lang.Thread.holdsLock() method returns true if and only if the current thread holds the monitor lock on the specified object.

Declaration

Following is the declaration for java.lang.Thread.holdsLock() method

public static boolean holdsLock(Object obj)

Parameters

obj − This is the object on which to test lock ownership.

Return Value

This method returns true if the current thread holds the monitor lock on the specified object.

Exception

NullPointerException − if obj is null.

Example

The following example shows the usage of java.lang.Thread.holdsLock() method.

package com.tutorialspoint;

import java.lang.*;

public class ThreadDemo implements Runnable {

   Thread th;

   public ThreadDemo() {

      th = new Thread(this);
      
      // this will call run() function
      th.start();
   }

   public void run() {

      /* returns true if and only if the current thread holds the
         monitor lock on the specified object */
      System.out.println("Holds Lock = " + Thread.holdsLock(this));  

      synchronized (this) {
         System.out.println("Holds Lock = " + Thread.holdsLock(this));
      }
   }

   public static void main(String[] args) {
      new ThreadDemo();
   }
}

Let us compile and run the above program, this will produce the following result −

Holds Lock = false
Holds Lock = TRUE