Difference between string object and string literal

When you do this:

String str = "abc";

You are calling the intern() method on String. This method references an internal pool of 'String' objects. If the String you called intern() on already resides in the pool, then a reference to that String is assigned to str. If not, then the new String is placed in the pool, and a reference to it is then assigned to str.

Given the following code:

String str = "abc";
String str2 = "abc";
boolean identity = str == str2;

When you check for object identity by doing == (you are literally asking - do these two references point to the same object?), you get true.

However, you don't need to intern() Strings. You can force the creation on a new Object on the Heap by doing this:

String str = new String("abc");
String str2 = new String("abc");
boolean identity = str == str2;

In this instance, str and str2 are references to different Objects, neither of which have been interned so that when you test for Object identity using ==, you will get false.

In terms of good coding practice - do not use == to check for String equality, use .equals() instead.