Difference Between ReentrantLock and Synchronized in Java

Java Object Oriented Programming Programming

There are two ways to get a lock on the shared resource by multiple threads. One is Reentrant Lock (Or ReadWriteLock ) and the other is by using the Synchronized method.

ReentrantLock class has been provided in Java concurrency package from Java 5.

It is the implementation of Lock interface and According to java docs, implementation of Lock interface provides more extensive operation than can be obtained using synchronized method.

Sr. No.	Key	ReentrantLock	Synchronized
1	Acquire Lock	Reentrant lock class provides lock() methods to get a lock on the shared resource by thread	You need to just write synchronized keyword to acquire a lock
2	Release Lock	To release lock , programmers have to call unlock() method	It is done implicitly
3	Ability to interrupt	lockInterruptibly() method can be used to interrupt the thread	There is no way to interrupt the thread
4	Fairness	Constructor of this class has fairness parameter. If it is set to true then locks favor granting access to the longest-waiting * thread	Lock does not guarantee any particular access orde
5	Lock Release Order	Lock can be released in any order	Lock should be released in the same order in which they were acquired

Example of ReentrantLock

public class ReentrantLockExample implements Runnable{
   private Lock lock=new ReentrantLock();
   @Override
   public void run() {
      try {
         lock.lock()
         //Lock some resource

      }
      catch (InterruptedException e) {
         e.printStackTrace();
      }
      finally {
         lock.unlock();
      }
   }
}

Example of SynchronizedLock

public class SynchronizedLockExample implements Runnable{
   @Override
   public void run() {
      synchronized (resource) {
         //Lock some resource
      }
   }
}

Mahesh Parahar

Updated on 18-Nov-2019 07:06:01

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