Java Reference
In-Depth Information
}
}
}
Directory "TryNestedClass2"
I put this version in the new folder
TryNestedClass2
. The only changes are the deletion of the
static
keyword in the definition of the
Rabbit
class and the movement of data members relating to rabbit names
to the
MagicHat
class. You can run this with the same version of
TryNestedClass
, and it should produce
output much the same as before.
How It Works
Although the output is much the same, what is happening is distinctly different. The
Rabbit
objects that
are created in the
MagicHat
constructor are now associated with the current
MagicHat
object that is be-
ing constructed. The
Rabbit()
constructor call is actually
this.Rabbit()
.
Using a Nested Class Outside the Top-Level Class
You can create objects of an inner class outside the top-level class containing the inner class. As I discussed,
how you do this depends on whether the nested class is a static member of the enclosing class. With the first
version of the
MagicHat
class, with a static
Rabbit
class, you could create an independent rabbit by adding
the following statement to the end of
main()
:
System.out.println("An independent rabbit: " + new MagicHat.Rabbit());
This
Rabbit
object is completely free — there is no
MagicHat
object to contain and restrain it. In the
case of a non-static
Rabbit
class, things are different. Let's try this using a modified version of the previous
program.
TRY IT OUT: Free-Range Rabbits (Almost)
You can see how this works by modifying the
main()
method in
TryNestedClass
to create another
Ma-
gicHat
object, and then create a
Rabbit
object for it:
static public void main(String[] args) {
// Create three magic hats and output them
System.out.println(new MagicHat("Gray Topper"));
System.out.println(new MagicHat("Black Topper"));
System.out.println(new MagicHat("Baseball Cap"));
MagicHat oldHat = new MagicHat("Old hat");
// New hat
object
MagicHat.Rabbit rabbit = oldHat.new Rabbit();
// Create
