Search:

That is the statement that is supposed to put a value in con, but it does not show what is in con when the code executes.
Add a println() statement just before the statement with the NPE that prints...

What is the value in con?

There is a variable with a null value on line xxx. Look at line xxx in the your source and see what variable is null. Then backtrack in the code to see why that variable does not have a valid value....