Why we don't have Integer pool like String we have in Java?

Answer 1

Not very sure about your question related to Integer and String pool however
if you use Integer.valueOf methods, you will get cached/common instance for same value used multiple times.

Which means this implicitly creates a pool of commonly used values.

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