How do you synchronize java?

Answer 1

Synchronizaion is the process by which only one Thread can access an object at a time,until and unless thread releases it's lock no other thread can acess the object. there are two forms of syncronization method and statement.

to make a method synchronized just add the keyword synchronized to the signature ie: public synchronized void increment() {

c++;

}

to create syncrhonized statements are like this:

synchronized(this) {

lastName = name;

nameCount++;

}

note: constructors can not be syncronized

Answer 2

Synchronization is a process where by a mutually-exclusive (mutex) lock is placed on a particular object for the duration of the execution of a block of code. It cannot be applied to primitives (double, int, etc.)

Synchronization ensures that only one thread has access to the synchronized object at a time, such as to prevent two threads from modifying a variable or to prevent the contents of a collection being changed while it is being iterated over.

Whole methods and arbitrary individual parts of one may be declared as synchronized.

An example of a synchronized method is:

public synchronized void setBalance(int amount) { ... }

Which effectively locks the object to which that method belongs (this), so it may be modified by only one thread at a time.

An example of a synchronized block, which requires exclusive access to the object myBankAccount is:

public void addMoney(Account act, int amount) {

// ... non-critical code can go here ...

synchronized(act) {

// it is imperative that nothing else is able to change

// the balance in this person's account while we do this!

act.setBalance(act.getBalance() + amount);

}

// ... more non-critical code can go here ...

}

In both cases, while either object is locked any additional threads which try to call either the setBalance or addMoney methods will block, meaning they will 'freeze' until they can gain exclusive access. Any code before or after the synchronized section can run as normal before and after the synchronized section completes: the block happens when a synchronized code section is encountered and it is not possible to get exclusive access to the target object.

Synchronization in Java is very expensive (in terms of time), and can easily become a performance bottleneck, however it is sometimes possible to overcome such performance loss simply moving superfluous synchronization to another place. In a situation where a data structure is being iterated over continually but rarely changed, it would be far slower to synchronize MyDataStructure.getData() resulting in continual, largely unnecessary locking/unlocking, than it would be simply to synchronize the add-/remove element methods.

Answer 3

Synchronization is the capability od controlling the access of multiple threads to any shared resource. It is used : 1) to prevent thread interface. 2)to prevent consistency problem