The volatile modifier is used to let the JVM know that a thread accessing the variable must always merge its own private copy of the variable with the master copy in the memory. Accessing a volatile variable synchronizes all the cached copied of the variables in the main memory.

Is volatile thread safe in Java?

Unlike synchronized methods or blocks, it does not make other threads wait while one thread is working on a critical section. Therefore, the volatile keyword does not provide thread safety when non-atomic operations or composite operations are performed on shared variables.

When should volatile be used?

A variable should be declared volatile whenever its value could change unexpectedly. In practice, only three types of variables could change: Memory-mapped peripheral registers.

What is the difference between volatile and transient in Java?

The volatile keyword flushes the changes directly to the main memory instead of the CPU cache. On the other hand, the transient keyword is used during serialization. Fields that are marked as transient can not be part of the serialization and deserialization.

What is difference between volatile and static?

volatile variable value access will be direct from main memory. It should be used only in multi-threading environment. static variable will be loaded one time. If its used in single thread environment, even if the copy of the variable will be updated and there will be no harm accessing it as there is only one thread.

What is volatile keyword used for?

The volatile qualifier is applied to a variable when we declare it. It is used to tell the compiler, that the value may change at any time. These are some properties of volatile. The volatile keyword cannot remove the memory assignment.

When should we use volatile in Java?

Yes, volatile must be used whenever you want a mutable variable to be accessed by multiple threads. It is not very common usecase because typically you need to perform more than a single atomic operation (e.g. check the variable state before modifying it), in which case you would use a synchronized block instead.

What is deadlock in Java?

Deadlock in Java is a condition where two or more threads are blocked forever, waiting for each other. This usually happens when multiple threads need the same locks but obtain them in different orders. Multithreaded Programming in Java suffers from the deadlock situation because of the synchronized keyword.

Is volatile necessary?

Conclusion. The volatile field is needed to make sure that multiple threads always see the newest value, even when the cache system or compiler optimizations are at work. Reading from a volatile variable always returns the latest written value from this variable.

Can we make array volatile in Java?

The answer is, Yes, you can make an array (both primitive and reference type array e.g. an int array and String array) volatile in Java but only changes to reference pointing to an array will be visible to all threads, not the whole array.

What is static volatile in Java?

A static variable in Java is stored once per class (not once per object, such as non-static variables are). This means all your objects (and static methods) share the same variable. Declaring a variable as volatile (be it static or not) states that the variable will be accessed frequently by multiple threads.

What is difference between transient and static?

The main difference between the two ( static versus transient ) is that static variables exist only once per transaction, but transient variables can exist many times. In other words, static variables have a global scope, while transient variables have a local scope.

What is serializable in Java?

To serialize an object means to convert its state to a byte stream so that the byte stream can be reverted back into a copy of the object. A Java object is serializable if its class or any of its superclasses implements either the java. io. Serializable interface or its subinterface, java.

What is volatile and atomic variable in Java?

Volatile and Atomic are two different concepts. Volatile ensures, that a certain, expected (memory) state is true across different threads, while Atomics ensure that operation on variables are performed atomically.

Can volatile variable be serialized?

Yes, it can be serialized. The field modifier volatile is used for the Java Memory Model to ensure that all Threads see a consistent value.

Why volatile is used in Singleton?

The volatile prevents memory writes from being re-ordered, making it impossible for other threads to read uninitialized fields of your singleton through the singleton’s pointer.