Null Check while passing Values to Context from UI

Hi All,

I am having around 10 Input fields in the UI from which any no of fields can be filled and sent to back end for a search. Where, none of the fields are mandatory. While sending to back end through Context, i want to pass each one of them as an uppercase String.

Is there any way to avoid Null pointer Exception by using TOUPPER method in this case.

Please Let me know all possible solutions for this Situation..

Thanking in advance,

Debasish