What is "arr"

Answer 1

What do you mean with what is arr? I can tell you that anytime you see arr in a java code, it's replacable by any other word as its just a variable name..

Answer 2

what is array

Answer 3

and what is its relation with Java

Answer 4

An array is nothing special in java. Array exists in every programming language out there and it's used frequently. Try and google it, you will find answers you will understand better than when someone here tries to explain...