What is synchronization in Java And why it is important?

[Adalbert]

Hi guys,
Can anyone tell me what synchronization does in java and how it is implemented, and it is important?

please Help.

[Michael25]

Synchronization is best use with the Multi-Threading in Java, Synchronization is the capability to control the access of multiple threads to share resources. Without synchronization it is possible for one thread to modify a shared object while another thread is in the process of using or updating that object's value.This often leads to an error.

Example for Synchronization
public synchronized void enqueue(Object item)
{
// Body of method goes here

}

shorthand notation for
public void enqueue(Object item)
{
synchronized (this)
{
//Body of method goes here
}
}

Hope this will give idea about synchronization and its code implementation.

[Expertz]

The Java programming language provides two basic synchronization idioms: synchronized methods and synchronized statements.
To make a method synchronized, simply add the synchronized keyword to its declaration:
public class SynchronizedCounter
{
private int c = 0;
public synchronized void increment()
{
c++;
}
public synchronized void decrement()
{
c--;
}
public synchronized int value()
{
return c;
}
}

If count is an instance of SynchronizedCounter, then making these methods synchronized has two effects:

* First, it is not possible for two invocations of synchronized methods on the same object to interleave. When one thread is executing a synchronized method for an object, all other threads that invoke synchronized methods for the same object block (suspend execution) until the first thread is done with the object.
* Second, when a synchronized method exits, it automatically establishes a happens-before relationship with any subsequent invocation of a synchronized method for the same object. This guarantees that changes to the state of the object are visible to all threads.