New to Java

Hi all,

I have the Nullpointer exception in my program and cannot pin point where the error is. I have a class called readText that reads ID's from text files. The IDs are 20 characters(all numerals) and i use substring [substr(0,21)] to pick it. I also have a method that is called from the readText class and this method have a SQL query. In the method are if-else statement to checks if the ID's equals either:
condition 1- IDs are 8 digits,
condtition 2- IDs are 7 digits
condtion 3- if its none of the above, then its invalid ID

The class and method have their own exception handling. Now, just recently i ran the program and the nullpointer exception came up. I checked the text and notice that there was an 9 digit ID. I debugged it and discovered that the problem was with the method conditions i set(like above). However, the twist is the error got caught by readText class exception handling and not the one in the method. Does that mean the error is in the class or method?????? Because if it was from the method, then it would have been caught in the method.

Can anyone help me out with this cause i've wecked my brain already just trying to figure it out.

Thanks yall

okun