Java Reference
In-Depth Information
8
SimpleTime time =
new
SimpleTime(
15
,
30
,
19
);
9
System.out.println(time.buildString());
10
}
11
}
// end class ThisTest
12
13
// class SimpleTime demonstrates the "this" reference
14
class
SimpleTime
15
{
16
private int
hour;
// 0-23
17
private int
minute;
// 0-59
18
private int
second;
// 0-59
19
20
// if the constructor uses parameter names identical to
21
// instance variable names the "this" reference is
22
// required to distinguish between the names
23
public
SimpleTime(
int
hour,
int
minute,
int
second)
24
{
25
this
.hour = hour;
// set "this" object's hour
this
.minute = minute;
// set "this" object's minute
this
.second = second;
// set "this" object's second
26
27
28
}
29
30
// use explicit and implicit "this" to call toUniversalString
31
public
String buildString()
32
{
33
return
String.format(
"%24s: %s%n%24s: %s"
,
34
"this.toUniversalString()"
,
this
.toUniversalString()
toUniversalString()
,
35
"toUniversalString()"
,
);
36
}
37
38
// convert to String in universal-time format (HH:MM:SS)
39
public
String toUniversalString()
40
{
41
// "this" is not required here to access instance variables,
42
// because method does not have local variables with same
43
// names as instance variables
44
return
String.format(
"%02d:%02d:%02d"
,
45
this
.hour
this
.minute
this
.second
,
,
);
46
}
47
}
// end class SimpleTime
this.toUniversalString(): 15:30:19
toUniversalString(): 15:30:19
Fig. 8.4
|
this
used implicitly and explicitly to refer to members of an object. (Part 2 of 2.)
Class
SimpleTime
(lines 14-47) declares three
private
instance variables—
hour
,
minute
and
second
(lines 16-18). The class's constructor (lines 23-28) receives three
int
arguments to initialize a
SimpleTime
object. Once again, we used parameter names for the
constructor (line 23) that are
identical
to the class's instance-variable names (lines 16-18),
so we use the
this
reference to refer to the instance variables in lines 25-27.
