Search:

What data type is the method defined to return?
What data type is surfaceGravi?
If they are not the same or compatible, then you need to change one or the other:
Either Define the method to return...

Please post the full text of the error message that shows the source statement where the error happens.

for(int count = 0; count < 9;count++)
You should the array's .length attribute to limit...