Java Reference
In-Depth Information
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.
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*/
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public static int
fillArray(
double
[] a)
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{
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System.out.println("Enter up to " + a.length
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+ " nonnegative numbers.");
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System.out.println("Mark the end of the list with a negative number.");
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Scanner keyboard =
new
Scanner(System.in);
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double
next;
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int
index = 0;
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next = keyboard.nextDouble();
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while
((next >= 0) && (index < a.length))
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{
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a[index] = next;
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index++;
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next = keyboard.nextDouble();
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//index is the number of array indexed variables used so far.
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}
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//index is the total number of array indexed variables used.
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if
(next >= 0)
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System.out.println("Could only read in "
41
+ a.length + " input values.");
The value of
index
is the number of
values stored in the array.
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return
index;
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}
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/**
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Precondition: numberUsed <= a.length.
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a[0] through a[numberUsed-1] have values.
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Returns the average of numbers a[0] through a[numberUsed-1].
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*/
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public static double
computeAverage(
double
[] a,
int
numberUsed)
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{
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double
total = 0;
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for
(
int
index = 0; index < numberUsed; index++)
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total = total + a[index];
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if
(numberUsed > 0)
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{
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return
(total/numberUsed);
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}
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else
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{
(continued)
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System.out.println("ERROR: Trying to average 0 numbers.");
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System.out.println("computeAverage returns 0.");
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return
0;
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}
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}
