Arrays - Absolute Java - page 370

Display 6.4 Partially Filled Array (part 2 of 3)

18 /**
19 Reads values into the array a. Returns the number of values placed
in the array a.
20 */
21 public static int fillArray( double [] a)
22 {
23 System.out.println("Enter up to " + a.length
24 + " nonnegative numbers.");
25 System.out.println("Mark the end of the list with a negative
number.");
26 Scanner keyboard = new Scanner(System.in);
27
28 double next;
29 int index = 0;
30 next = keyboard.nextDouble();
31 while ((next >= 0) && (index < a.length))
32 {
33 a[index] = next;
34 index++;
35 next = keyboard.nextDouble();
36 //index is the number of array indexed variables used so far.
37 }
38 //index is the total number of array indexed variables used.
39 if (next >= 0)
40 System.out.println("Could only read in "
41 + a.length + " input values.");

42 return index;
43 }

The value of index is the number of
values stored in the array.

44 /**
45 Precondition: numberUsed <= a.length.
46 a[0] through a[numberUsed-1] have values.
47 Returns the average of numbers a[0] through a[numberUsed-1].
48 */
49 public static double computeAverage( double [] a, int numberUsed)
50 {
51 double total = 0;
52 for ( int index = 0; index < numberUsed; index++)
53 total = total + a[index];
54 if (numberUsed > 0)
55 {
56 return (total/numberUsed);
57 }
58 else
59 {
60 System.out.println("ERROR: Trying to average 0 numbers.");
61 System.out.println("computeAverage returns 0.");
62 return 0;
63 }
64 }