How to set entries of spinner in android while using if else

I have two spinners, spGrade and spBlock

The spGrade has its own array-list containing numbers "11" and "12", while the other one, i made two array-lists named spBlock11 and spBlock12. (the array-lists are in the string.xml)

If spGrade selects the first array, i want to set the entries of spBlock as spBlock11

and if spGrade selects the second array, i want to set the entries of spBlock as spBlock12

What is the code for that?