Strange probelm with Strings

[sk_azeez]

I am getting one string from some application
If I pass the string to LOG4J it is printing properly
But If i try to access the string after certain number of characters I am failing to access that string

Lets say I am getting a string of "Hello how r u? **T** ect ect"

I am able to print entire string with LOG4J but If i use substring I am unable to access after '*'
Ex:
str.substring(0,5) ----Hello (fine)
str.substring(15,20)----printing nothing (where is my **T**?????)