Java Reference
In-Depth Information
variable is initialized to zero in line 7. If a
static
variable is
not
initialized, the compiler
assigns it a default value—in this case
0
, the default value for type
int
.
1
// Fig. 8.12: Employee.java
2
// static variable used to maintain a count of the number of
3
// Employee objects in memory.
4
5
public class
Employee
6
{
7
private static int
count =
0
;
// number of Employees created
8
private
String firstName;
9
private
String lastName;
10
11
// initialize Employee, add 1 to static count and
12
// output String indicating that constructor was called
13
public
Employee(String firstName, String lastName)
14
{
15
this
.firstName = firstName;
16
this
.lastName = lastName;
17
18
++count;
// increment static count of employees
19
System.out.printf(
"Employee constructor: %s %s; count = %d%n"
,
20
firstName, lastName, count);
21
}
22
23
// get first name
24
public
String getFirstName()
25
{
26
return
firstName;
27
}
28
29
// get last name
30
public
String getLastName()
31
{
32
return
lastName;
33
}
34
35
// static method to get static count value
public static int
getCount()
{
return
count;
}
36
37
38
39
40
}
// end class Employee
Fig. 8.12
|
static
variable used to maintain a count of the number of
Employee
objects in
memory.
When
Employee
objects exist, variable
count
can be used in any method of an
Employee
object—this example increments
count
in the constructor (line 18). The
public
static
method
getCount
(lines 36-39) returns the number of
Employee
objects that have
been created so far. When no objects of class
Employee
exist, client code can access variable
count
by calling method
getCount
via the class name, as in
Employee.getCount()
. When
objects exist, method
getCount
can also be called via any reference to an
Employee
object.
