AtomicInteger is implemented base on JNI?

Question

Soneone told me that AtomicInteger is implemented using JNI, so it is much faster than synchonization. Is this true?

Answer 1

It is unlikely to be implemented based on JNI as this would imply significant overhead. Last time I looked the OpenJDK implementation is based on methods in sun.misc.Unsafe which are mostly implemented as JVM primitives (method calls that are implemented specially with native code in the JVM).