Java Reference
In-Depth Information
97
98
99
100
101
102
// for each grade frequency, print bar in chart
103
for
(
int
count =
0
; count < frequency.length; count++)
104
{
105
// output bar label ("00-09: ", ..., "90-99: ", "100: ")
106
if
(count ==
10
)
107
System.out.printf(
"%5d: "
,
100
);
108
else
109
System.out.printf(
"%02d-%02d: "
,
110
count *
10
, count *
10
+
9
);
111
112
// print bar of asterisks
113
for
(
int
stars =
0
; stars < frequency[count]; stars++)
114
System.out.print(
"*"
);
115
116
System.out.println();
117
}
118
}
119
120
// output the contents of the grades array
121
public
void
outputGrades()
122
{
123
System.out.printf(
"The grades are:%n%n"
);
124
125
// output each student's grade
126
127
// for each grade, increment the appropriate frequency
for
(
int
grade : grades)
++frequency[grade /
10
];
for
(
int
student =
0
; student < grades.length; student++)
System.out.printf(
"Student %2d: %3d%n"
,
student + 1, grades[student]);
128
129
}
130
}
// end class GradeBook
Fig. 7.14
|
GradeBook
class using an array to store test grades. (Part 3 of 3.)
Method
processGrades
(lines 29-43) contains a series of method calls that output a
report summarizing the grades. Line 32 calls method
outputGrades
to print the contents
of the array
grades
. Lines 126-128 in method
outputGrades
output the students' grades.
A counter-controlled
for
statement
must
be used in this case, because lines 127-128 use
counter variable
student
's value to output each grade next to a particular student number
(see the output in Fig. 7.15). Although array indices start at 0, a professor might typically
number students starting at 1. Thus, lines 127-128 output
student + 1
as the student
number to produce grade labels
"Student 1: "
,
"Student 2: "
, and so on.
Method
processGrades
next calls method
getAverage
(line 35) to obtain the average
of the grades in the array. Method
getAverage
(lines 78-88) uses an enhanced
for
state-
ment to total the values in array
grades
before calculating the average. The parameter in
the enhanced
for
's header (e.g.,
int grade
) indicates that for each iteration, the
int
vari-
able
grade
takes on a value in the array
grades
. The averaging calculation in line 87 uses
grades.length
to determine the number of grades being averaged.
