String Pool or Intern pool

Strings are everywhere in Java, they use a lot of memory. How does Java solves this problem?

Answer : It collects all this strings and store them in a location called String Pool or Intern Pool in JVM. This location contains literal values and constants that appears in your program.

Consider the following

var x = "Hello World";
var y = "Hello World";
System.out.println(x == y);        

JVM creates one literal in memory and both x and y point's to the same location in the memory. Therefore it prints true.

How about the following?

var x = "Hello World";
var y = "   Hello World".trim();
System.out.println(x==y)        

This will be false. Although, x and y evaluates to the same value one is computed at runtime and the other is at compile time. How about a simple simple concatenation like the following?

var x = "hello world";
var y = "hello";
y += " world";
System.out.println(x==y);        

This will also be false as concatenation is the same as calling a method.

What is the difference between the two statements below?

var x = "Hello World";
var y = new String("Hello World");        

First, one says to use the normal String Pool while the second one says "No JVM, No String Pool, Just Please Create a New Object"

How about if we want to force the String object created by "new" to refer to the String Pool?

var y = new String("Hello World").intern();        

#Java #StringPool