Little things that causes errors:

1. If you have a throw e; e is an exception line in catch, in the method
that throws the exception, you have to have throw Exception line declared
in the method name.

2. a java variable can not use the character dash “-“, it will give obscure
error message if you have a variable name such as list-req, instead you should
make the variable name list_req, use underscore instead

3. For some reason, you will get a error if you have several try & catch block
inside one method. Make sure you put the throw exception line at the really last
block of try & catch, don’t throw exception before the last block.