CLASSES
Examples of Field Declarations
8.3.3
8.3.3.1
Example: Hiding of Class Variables
The example:
class Point {
static int x = 2;
}
class Test extends Point {
static double x = 4.7;
public static void main(String[] args) {
new Test().printX();
}
void printX() {
System.out.println(x + " " + super.x);
}
}
produces the output:
4.7 2
because the declaration of
x
 in class
Test
 hides the definition of
x
 in class
Point
,
so class
Test
 does not inherit the field
x
 from its superclass
Point
. Within the
declaration of class
Test
, the simple name
x
 refers to the field declared within
class
Test
. Code in class
Test
 may refer to the field
x
 of class
Point
 as
super.x
(or, because
x
 is
static
, as
Point.x
). If the declaration of
Test.x
 is deleted:
class Point {
static int x = 2;
}
class Test extends Point {
public static void main(String[] args) {
new Test().printX();
}
void printX() {
System.out.println(x + " " + super.x);
}
}
then the field
x
 of class
Point
 is no longer hidden within class
Test
; instead, the
simple name
x
 now refers to the field
Point.x
. Code in class
Test
 may still refer
to that same field as
super.x
. Therefore, the output from this variant program is:
2 2
8.3.3.2
Example: Hiding of Instance Variables
This example is similar to that in the previous section, but uses instance variables
rather than static variables. The code:
151






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