Because I want others who might have the same problem to find a solution, I will post what finally worked after tirelessly looking for a solution:
- Create a new textfield with a class type Double then add the following in your texfield expression:
new Double($V{TOT_EXPENSE}.doubleValue() == 0 ? 0 : ($V{TOT_INCOME}.doubleValue()-$V{TOT_EXPENSE}.doubleValue()))
Done!! This Worked for me.