New to Java

Hi there!

I am a student currently doing my FYP(Final Year Project). Is there any code that i can use to convert void to String? I am using apache POI HSSF(Horrible SpreadSheet Format) to retrieve some data from typical MicroSoft Excel so that i can convert it to pure java and use JDBC to store the value into the server's database.

Now, the problem occurs if the user happens to leave certain mandatory fields blank and uploads the Excel(.xls) file into the server without double checking his/her work. This causes the program to fail.

I had tried to use other methods from the API such as setCellValue(); but always got the
"Type mismatch: cannot convert from void to String"
error.

Greatly appreaciate anyone that can give me good suggestions as to solve this problem.If not, thanks for reading this.

-OrangeFlash-