What use does the == operator have for String?

In Java, if one is to check if two Strings are equal, in the sense that their values are the same, he/she needs to use the equals method. E.g. :

String foo = "foo"; 
String bar = "bar";
if(foo.equals(bar)) { /* do stuff */ }

And if one wants to check for reference equality he needs to use the == operator on the two strings.

if( foo == bar ) { /* do stuff */ }

So my question is does the == operator have it's use for the String class ? Why would one want to compare String references ?

Edit: What I am not asking : How to compare strings ? How does the == work ? How does the equals method work?

What I am asking is what uses does the == operator have for String class in Java ?