Can AtomicInteger replace synchronized?

Question

The javadoc for the java.util.concurrent.atomic package says the following:

A small toolkit of classes that support lock-free thread-safe programm

Answer 1

Is volatile needed when I use AtomicInteger?

Not necessarily. Considering your example:

• if i is a local variable, or
• if i is a final attribute, or
• if the current thread and the thread that initialized (or last updated) the i variable have synchronized after that event,

then it makes no difference if you declare i as volatile or not.