Скачать или смотреть Learn Java Programming - String Class Part 3 Tutorial

In this tutorial, I will introduce you to the concept of the String Literal Pool (aka String Constant Pool). The String Pool exists as a special section of the heap memory and it contains distinct instances of string literal values. In part one I stated "... that the string literal "ABC" is equivalent to new String("ABC") in the compiled code." and that is essentially correct. However, there is one subtle difference that warrants explanation. In order to increase performance and save memory, string literal instances are stored in a special section of the heap memory reserved for distinct string values (string pool). When a reference to a string literal is being created, Java first checks for a string with same value in the string literal pool, if one does exist it just returns that reference, otherwise a new string literal instance will be created in the pool and that reference is returned.
In the statement String s = "ABC"; the "ABC" literal instance will be stored in the string pool section of heap memory.
In the statement String s = new String("ABC"); the instance with the value of "ABC" will be stored in regular good old heap memory.
Why the difference? To increase performance and save memory.