The Java Thread holdsLock() method returns true if and only if the current thread holds the monitor lock on the specified object.
DeclarationFollowing 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 ValueThis method returns true if the current thread holds the monitor lock on the specified object.
ExceptionNullPointerException − if obj is null.
Example: Checking if a thread holds lock as trueThe following example shows the usage of Java Thread holdsLock() method. In this program, we've created a class ThreadDemo. In main method, we've created a new thread and started it using start() method. In run() method, we're print hold lock status using holdsLock() method. Being in synchronized block, holdsLock() method returns true.
package com.tutorialspoint; 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 */ synchronized (this) { System.out.println("Holds Lock = " + Thread.holdsLock(this)); } } public static void main(String[] args) { new ThreadDemo(); } }Output
Let us compile and run the above program, this will produce the following result −
Holds Lock = trueExample: Checking if a thread holds lock as false
The following example shows the usage of Java Thread holdsLock() method. In this program, we've created a class ThreadDemo. In main method, we've created a new thread and started it using start() method. In run() method, we're print hold lock status using holdsLock() method. Being not in synchronized block, holdsLock() method returns false.
package com.tutorialspoint; 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)); } public static void main(String[] args) { new ThreadDemo(); } }Output
Let us compile and run the above program, this will produce the following result −
Holds Lock = false
java_lang_thread.htm
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