Question

ArrayList in java is thread safe.and it is implemented using array.

So, is the access to arrays in java thread safe??does the access to arrays needs to be synchronized??

Answer 1

No, ArrayList isn’t thread-safe in Java.

From the docs:

Note that this implementation is not synchronized. If multiple threads access an ArrayList
instance concurrently, and at least one of the threads modifies the list structurally, it
must be synchronized externally.

Are you thinking of Vector, which uses synchronization internally? (Each method is synchronized, basically.)