How can I compare void values with null?

Question

https://code.sololearn.com/ca76K3gY7x8c/?ref=app

Answer 1

https://code.sololearn.com/c4bmtTf64XrJ/?ref=app

Answer 2

Thanks, so much

Answer 3

null itself is used to determine that the value is void (which means nothing)
Suppose you have a grade system with integer subject
So you have an integer object of subject like

Integer subject1=0; // you got 0 in subject1
Integer subject2=null; // your score of subject2 is not available

Answer 4

I already know that, my question is when you don't type any value from a scanner how you compare that void.
With null doesn't work so...

Answer 5

I mean with no such element exeption