[ANSWERED]String concatenation

Question

String a = "a", b ="b", c="ab";
I know from testing that
a+b!=c
Any brief answers why it is so?

Answer 1

In java String is an object type.
!= and == it's a reference comparison.
Different references reference different objects with the same content.

To compare content use method
(object1).equals(object2)

String is immutable object.
When you concatenate strings a new string object is built.