Question

Recently in a job interview I was asked this following question (for Java):

Given:

String s1 = "abc";
String s2 = "abc";

What is the return value of

(s1 == s2)

I answered with it would return false because they are two different objects and == is a memory address comparison rather than a value comparison, and that one would need to use .equals() to compare String objects. I was however told that although the .equals(0 methodology was right, the statement nonetheless returns true. I was wondering if someone could explain this to me as to why it is true but why we are still taught in school to use equals()?

Answer 1

java will intern both strings, since they both have the same value only one actual string instance will exist in memory – that’s why == will return true – both references point to the same instance.

String interning is an optimization technique to minimize the number of string instances that have to be held in memory. String literals or strings that are the values of constant expressions, are interned so as to share unique instances. Think flyweight pattern.