while loop

Question

Hello ...
please help me ...
How to Java ...
Write a program using the ring while an unknown number grade that are of a, b, c, e, d User and received from them to resurrection
A = 4.0;
B = 3.0;
C = 2.0;
D = 1.0;
E = 0.0;
And the average grade convert the count

Answer 1

are the number of grades unknown?