Java Reference
In-Depth Information
example, if
Cell
objects are only intended for use within
SingleLinkQueue
objects, then it would be reasonable for
Cell
to be a static nested class
within
SingleLinkQueue
:
class SingleLinkQueue<E> {
static class Cell<E> {
private Cell<E> next;
private E element;
public Cell(E element) {
this.element = element;
}
public Cell(E element, Cell<E> next) {
this.element = element;
this.next = next;
}
public E getElement() {
return element;
}
/* ... rest of Cell methods as before ... */
}
protected Cell<E> head;
protected Cell<E> tail;
/* ... rest of SingleLinkQueue methods as before ... */
}
The code in
Cell
and
SingleLinkQueue
is unchanged except that
Cell
is de-
clared as a static nested class within
SingleLinkQueue
. The type variable
E
is used for both classes because the element type of a cell must always
match the element type of the queue it is part of, but they are distinct
names. The two different
E
types are associated in the declarations of
head
and
tail
, where the
E
type parameter of the
SingleLinkQueue
class
defines the parameterized type
Cell<E>
. As always, you should choose
names carefully and avoid confusion. If the type variables should always
