Shadowing
Shadowing refers to the practice of using two variables with the same name within scopes that overlap. When you do that, the variable with the higher-level scope is hidden because the variable with lower-level scope overrides it. The higher-level variable is then “shadowed.”
You can access a shadowed class or instance variable by fully qualifying it — that is, by providing the name of the class that contains it.
For example, consider this program:
public class ShadowApp
{
static int x;
public static void main(String[] args)
{
x = 5;
System.out.println(“x = “ + x);
int x;
x = 10;
System.out.println(“x = “ + x);
System.out.println(”ShadowApp.x = ” +
ShadowApp.x);
}
}
Here is the output:
x = 5
x = 10
x = 10
ShadowApp.x = 5
Here, the first System.out.println
statement prints the value of the class variable x
. Then, the class variable x
is shadowed by the local variable x
, whose value is printed by the second System.out.println
statement. Finally, the third System.out.println
statement prints the shadowed class variable by providing its fully qualified name (ShadowApp.x
).
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