| Binding Data to Graph Elements | ||
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This page is from the outdated yFiles for Java 2.13 documentation. You can find the most up-to-date documentation for all yFiles products on the yFiles documentation overview page.
Please see the following links for more information about the yFiles product family of diagramming programming libraries and corresponding yFiles products for modern web apps, for cross-platform Java(FX) applications, and for applications for the Microsoft .NET environment.
Most notably graph algorithms expect certain information asscociated with the graph elements they process. For example, a Shortest Path algorithm from package y.algo needs cost data associated with the edges of a graph.
The yFiles library uses the concept of data accessors to bind this information
to graph elements.
The general term "data accessor" comprises both storing data and retrieving
data, i.e., setter methods (write behavior) and getter methods (read behavior).
The actual implementations of these two aspects are interfaces
DataProvider
and
DataAcceptor.
DataProvider defines read-only behavior on the contained data, its
counterpart DataAcceptor defines write-only behavior.
The most frequently used data accessors, for example, interfaces
NodeMap and
EdgeMap, have
read/write behavior, i.e., they inherit from both DataProvider and
DataAcceptor.
However, there are many cases where read-only behavior is sufficient.
This is especially true for situations where the supplemental data is
given as a parameter to a method, for example.
In general, using data accessors presents a flexible approach, since the realization of the actual data store is not constrained to given implementations but can be extended in any imaginable way. Also, there is no restriction on the number or the implementation of each type of custom data associated with a graph element.
Normally, i.e., in popular object-oriented belief, customizing existent functionality means using inheritance. The yFiles graph implementation, however, disfavors this approach for the sake of the same technique used to provide supplemental data to graph elements. Instead of extending any of class Node or class Edge, arbitrary custom data can be bound to any instance of these classes by using data accessors.
The tutorial demo application ExtendedGraph.java shows how the Graph class itself can be subclassed in order to provide additional data with the graph elements.
The following topics have been discussed in this chapter:
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