The difference between ReentrantLock and synchronization in Java

There are two methods to lock shared resources using multiple threads. One is the reentrant lock (Or ReadWriteLock), and the other is by using the Synchronized method.

Java 5The ReentrantLock class is provided in the Java concurrency package.　

It is the implementation of the Lock interface. According to java docs, the implementation of the Lock interface provides a wider range of operations than those that can be obtained by using synchronized methods.

Number	Key	Reentrant lock	Synchronized
1	Obtain lock	The ReentrantLock class provided by the ReentrantLock class`lock()`The method to obtain the shared resource lock through threads	You only need to write the synced keyword to get the lock
2	Release lock	To release the lock, the programmer must call`unlock()`Method	Implicit completion
3	Interruptibility	The lockInterruptible() method can be used to interrupt a thread	There is no way to interrupt a thread
4	Fairness	The constructor of this class has a fairness parameter. If it is set to true, the lock will be granted to the one who has been waiting the longest　*Thread access permission	Lock does not guarantee any specific access permission
5	Lock release order	Locks can be released in any order	Locks should be released in the order of obtaining the lock

ReentrantLock example

public class ReentrantLockExample implements Runnable{
　　　private Lock lock = new ReentrantLock();
　　　@Override
　　　public void run() {
　　　　　　try {
　　　　　　　　　lock.lock()
　　　　　　　　　//Lock some resources
　　　　　　}
　　　　　　catch (InterruptedException e) {
　　　　　　　　　e.printStackTrace();
　　　　　　}
　　　　　　finally {
　　　　　　　　　lock.unlock();
　　　　　　}
　　　}
}

SynchronizedLock example

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

Basic Tutorial