Atomic Operations and multithreading

Question

Recently I was reading a tutorial, in that I came across a statement that says..

\"The Java language specification guarantees that reading or writing a variable is

Answer 1

atomicity of an operation is required when you mutate a variable. doing int a = 10; is an atomic operation but its not the one which will give you the problem. the problem giving operations usually are mutating ones like a++ or a = a + 2; and so on.

Java Specification guarantees that 'reading' and 'writing' are atomic operations not their combinations. so an operation which 'reads, adds 1 and then writes the result back' is not atomic as per specification. such operations are called compound operations and they usually need to be atomic in context of their usage in our code.

Atomic types help solve this problem. using incrementAndget() on an atomic type makes 'reads, adds 1 and then writes the result back and reads the new result' a single atomic operation in context to thread safety.

Hope this helps. By the way you should read this (http://walivi.wordpress.com/2013/08/24/concurrency-in-java-a-beginners-introduction/) article about basics of concurrency and threads. it explains such stuff beautifully.