What is the fastest way to convert a string into an integer in Java?

Question

I want to convert a string say "98989" into an integer without using any library functions in java. Give fastest way to do it and explain why your method is best.

Answer 1

String str = "1234";
int num = Integer.parseInt(str);

To convert a number into a string, use:

int num = 1234;   
String str = String.valueOf(num);

Answer 2

Integer.valueOf is fastest because it uses cached instance. So if there already exists a Integer in pool with value 98989,
that will be returned instead of creating new Integer instance.

Check this for details.
http://docs.oracle.com/javase/7/docs/api/java/lang/Integer.html#valueOf(int)