Java How to Program, Early Objects, 11th Edition

... grade = input.nextInt();     
18
19      // loop until sentinel value read from user   
20      while (grade != -1) { 
21         total = total + grade; // add grade to total 
22         gradeCounter = gradeCounter + 1; // increment counter 
23
24         // prompt for input and read next grade from user
25         System.out.print("Enter grade or -1 to quit: ");
26         grade = input.nextInt(); 
27      } 
28
29      // termination phase 
30      // if user entered at least one grade… 
31      if (gradeCounter != 0) { 
32         // use number with decimal point to calculate average of grades
33         double average = (double) total / gradeCounter;     
34
35         // display total and average (with two digits of precision) 
36         System.out.printf("%nTotal of the %d grades entered is %d%n", 
37            gradeCounter, total); 
38         System.out.printf("Class average ...