Java - using AtomicInteger vs Static int

Question

While using multiple threads I have learnt to use Static variables whenever I want to use a counter that will be accessed by multiple threads.

Example:

static int count=0; Then later in the program I use it as count++;.

Today I came across something called AtomicInteger and I also learned that it is Thread safe and could use one of its methods called getAndInrement() to achieve the same effect.

Could anyone help me to understand about using static atomicInteger versus static int count?

Answer 1

- AtomicInteger is used to perform the atomic operation over an integer, its an alternative when you don't want to use synchronized keyword.

- Using a volatile on a Non-Atomic field will give inconsistent result.

int volatile count;

public void inc(){

count++

}

- static will make a variable shared by all the instances of that class, But still it will produce an inconsistent result in multi-threading environment.

So try these when you are in multithreading environment:

1. Its always better to follow the Brian's Rule:

When ever we write a variable which is next to be read by another thread, or when we are reading a variable which is written just by another thread, it needs to be synchronized. The shared fields must be made private, making the read and write methods/atomic statements synchronized.

2. Second option is using the Atomic Classes, like AtomicInteger, AtomicLong, AtomicReference, etc.