TestGrade.java

import java.util.Scanner;

public class TestGrade {

  public static void main(String [ ] args) {

  int numberOfGrades;
  int total = 0;
  float average;
  Scanner keyboard = new Scanner(System.in);

  // Get the number of grades
  do {
    System.out.println("How many grades do you have to enter?\n");
    while( !keyboard.hasNextInt() ) {
      System.out.println("Grade count must be between 0 and 5. How many grades do you have to enter?\n");
      keyboard.next();
    }

    numberOfGrades = keyboard.nextInt();
  } while (numberOfGrades < 0 && numberOfGrades > 5);

  // Get the grades total
  for (int i=1; i<=numberOfGrades; i++) {
    int grade;

    do {
      System.out.format("Enter grade %d: ", i);
      while ( !keyboard.hasNextInt() ) {
        System.out.println("\nInvalid grade. Try again: ");
        keyboard.next();

      }
      grade = keyboard.nextInt();
    } while (grade < 0);

    total += grade;
   }

   // Average the grades
   average = total/numberOfGrades;

   // Print the average
   System.out.format("Grade average is %f", average);

  }
}