Data Structures and Algorithms
with Object-Oriented Design Patterns in Java 
Directed graphs and undirected graphs have many common characteristics.
In addition, we can view a directed graph as an undirected graph
with arrowheads added.
As shown in Figure 
,
we have chosen to define the Graph interface
to represent undirected graphs
and to derive Digraph interface from it.
We have chosen this approach because many algorithms
for undirected graphs can also be used with directed graphs.
On the other hand, it is often the case that algorithms
for directed graphs cannot be used with undirected graphs.
Program defines the Graph interface.
The Graph interface extends the Container interface
defined in Program .
There are essentially three groups of methods declared in Program :
accessors and mutators, enumerations, and traversals.
The operations performed by the methods
are explained in the following sections.
Copyright © 1998 by Bruno R. Preiss, P.Eng. All rights reserved.
