Java Reference
In-Depth Information
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// Fig. 8.1: Time1.java
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// Time1 class declaration maintains the time in 24-hour format.
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4
public class
Time1
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{
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private int
hour;
// 0 - 23
private int
minute;
// 0 - 59
private int
second;
// 0 - 59
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8
9
10
// set a new time value using universal time; throw an
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// exception if the hour, minute or second is invalid
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public void
setTime(
int
hour,
int
minute,
int
second)
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{
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// validate hour, minute and second
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if
(hour <
0
|| hour >=
24
|| minute <
0
|| minute >=
60
||
16
second <
0
|| second >=
60
)
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{
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throw new
IllegalArgumentException(
"hour, minute and/or second was out of range"
);
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}
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this
.hour = hour;
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this
.minute = minute;
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this
.second = second;
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}
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// convert to String in universal-time format (HH:MM:SS)
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public
String toUniversalString()
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{
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return
String.format(
"%02d:%02d:%02d"
, hour, minute, second);
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}
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// convert to String in standard-time format (H:MM:SS AM or PM)
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public
String toString()
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{
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return
String.format(
"%d:%02d:%02d %s"
,
((hour ==
0
|| hour ==
12
) ?
12
: hour %
12
),
minute, second, (hour <
12
?
"AM"
:
"PM"
));
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}
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}
// end class Time1
Fig. 8.1
|
Time1
class declaration maintains the time in 24-hour format.
Default Constructor
In this example, class
Time1
does
not
declare a constructor, so the compiler supplies a de-
fault constructor. Each instance variable implicitly receives the default
int
value. Instance
variables also can be initialized when they're declared in the class body, using the same ini-
tialization syntax as with a local variable.
Method
setTime
and Throwing Exceptions
Method
setTime
(lines 12-25) is a
public
method that declares three
int
parameters and
uses them to set the time. Lines 15-16 test each argument to determine whether the value
is outside the proper range. The
hour
value must be greater than or equal to
0
and less than
