Lock Interface In Concurrency API

Q- What is lock in java?
A lock is a thread synchronization mechanism like synchronized blocks except locks can be more sophisticated than Java's synchronized blocks.

Lock interface:  Lock interface is present in java.util.concurrent.locks package
ReentrantLock: ReentrantLock is a class which implements the Lock interface and provides synchronization to methods while accessing shared resources.

• void lock()
• void unlock()
• boolean tryLock() 
• boolean tryLock(long timeout, TimeUnit timeUnit) 
• void lockInterruptibly() 
• getHoldCount():
• isHeldByCurrentThread():

  Lock implementations  
ReentrantLock class implements the Lock interface.

  ReadWriteLock interface  

• Lock readLock() – returns the lock that’s used for reading
• Lock writeLock() – returns the lock that’s used for writing

ReentrantReadWriteLock: ReentrantReadWriteLock class implements the ReadWriteLock interface.

• Read Lock – if no thread acquired the write lock or requested for it then multiple threads can acquire the read lock
• Write Lock – if no threads are reading or writing then only one thread can acquire the write lock

ReadWriteLock lock = new ReentrantReadWriteLock();
Lock writeLock = lock.writeLock();
Lock readLock = lock.readLock();

  StampedLock  

StampedLock is introduced in Java 8. It also supports both read and write locks.

  Conditions  
The Condition class provides the ability for a thread to wait for some condition to occur while executing the critical section.

ReentrantLock lock = new ReentrantLock();
Condition condition1 = lock.newCondition();
Condition condition1 = lock.newCondition();
 

Related Tutorials

• Lock In Java Example
• Differences between Lock and Synchronized block
• Method And Block Synchronization In Java Example
• How To Create Custom Lock
• Fair Lock In Java Example