What is the use of synchronization in java e.g. java arraylist is non synchronized... what does it really means

Question

need suggestions

Answer 1

@Felipe Is it like I have an Array List, if I run Thread A and Thread B, in which Thread A remove one of the element in the Array List, then the index of the other elements after it will change, then when I access the Array List in Thread B will cause problem?

Answer 2

It is a multithread concept.

Synchronized methods enable a simple strategy for preventing thread interference and memory consistency errors.

Accessing an ArrayList instance from multiple threads may not be thread safe if you don't manage that.