Any concept of shared memory in Java

Question

AFAIK, memory in Java is based on heap from which the memory is allotted to objects dynamically and there is no concept of shared memory.

If there is no concept of s

Answer 1

The information provided by Cowan is correct. However, even shared memory won't always appear to be identical in multiple threads (and/or processes) at the same time. The key underlying reason is the Java memory model (which is built on the hardware memory model). See Can multiple threads see writes on a direct mapped ByteBuffer in Java? for a quite useful discussion of the subject.