Java Reference
In-Depth Information
{
nodeBefore = currentNode;
currentNode = currentNode.getNextNode();
}
// end while
if
( (currentNode !=
null
) && key.equals(currentNode.getKey()) )
{
result = currentNode.getValue();
currentNode.setValue(value);
// replace value
}
else
{
Node newNode =
new
Node(key, value);
// create new node
numberOfEntries++;
// increase length for both cases
if
(nodeBefore ==
null
)
{
// add at beginning (includes empty chain)
newNode.setNextNode(firstNode);
firstNode = newNode;
}
else
// add elsewhere in non-empty chain
{
newNode.setNextNode(currentNode);
// currentNode is after new
// node
nodeBefore.setNextNode(newNode);
// nodeBefore is before new
// node
}
// end if
}
// end if
return
result;
}
// end add
<
Implementations of the other methods in
DictionaryInterface
>
. . .
<
Private classes
KeyIterator
and
ValueIterator
(See Segment 20.26)
>
. . .
<
The private class
Node
>
. . .
}
// end SortedLinkedDictionary
20.25
Iterators.
As we mentioned in Segment 20.20, iterators provide the client with an easy way to traverse
a dictionary's search keys and their corresponding values. The public methods
getKeyIterator
and
getValueIterator
have the same implementations here as they do in
SortedVectorDictionary
. The
private inner classes
KeyIterator
and
ValueIterator
, however, differ. Each has a data field
nextNode
to mark an iteration's place in the chain as the traversal progresses. Listing 20-6 shows the private class
