/**
* The default constructor. It sets the edge's vertices based on the supplied starting and ending
* vertices. The vertices should be different and must have their IDs set to a non-negative
* integer. It registers the edge as a listener with the provided vertices.
*
* @param start
* <p>The first Vertex in this Edge.
* @param end
* <p>The second Vertex in this Edge.
*/
public Edge(Vertex start, Vertex end) {
// The expected behavior is that if the supplied Vertices are invalid,
// then the edge's default vertices become an empty list and its length
// becomes -1.
// The vertices are valid if:
// they are non-null Vertex instances
// they are not the same reference
// there are exactly 2 Vertex instances
// Initialize the defaults.
this();
// The supplied Vertices must not be null and must not be the same.
if (start == null || end == null || start.getId() == end.getId()) {
throw new IllegalArgumentException(
"Edge error: start and end vertices must not be null and must not have the same ID.");
}
// Set the vertex IDs.
vertices[0] = start;
vertices[1] = end;
// Update the length
updateLength();
// Register with the vertices.
start.register(this);
end.register(this);
return;
}
/**
* This constructor takes a collection of vertices. The collection should contain only two
* different vertices. They must have their IDs set to a non-negative integer. It registers the
* edge as a listener with the provided vertices.
*
* @param vertices
* <p>The two Vertices this Edge connects.
*/
public Edge(ArrayList<Vertex> vertices) {
// The expected behavior is that if the supplied ArrayList of Vertices
// is invalid, then the edge's default vertices become an empty list and
// its length becomes -1.
// The vertices are valid if:
// they are non-null Vertex instances
// they are not the same reference
// there are exactly 2 Vertex instances
// Initialize the defaults.
this();
// The supplied ArrayList must not be null and must have two elements.
if (vertices == null || vertices.size() != 2) {
throw new IllegalArgumentException(
"Edge error: The vertex ArrayList must not be null and must have 2 elements.");
}
// Make sure the vertices are not null and are not the same
// reference.
Vertex start = vertices.get(0);
Vertex end = vertices.get(1);
// The supplied Vertices must not be null and must not be the same.
if (start == null || end == null || start.getId() == end.getId()) {
throw new IllegalArgumentException(
"Edge error: start and end vertices must not be null and must not have the same ID.");
}
// Set the vertex IDs.
this.vertices[0] = start;
this.vertices[1] = end;
// Update the length
updateLength();
// Register with the vertices.
start.register(this);
end.register(this);
return;
}
/** Updates the Edge if the Vertex's ID matches one of its stored Vertices. */
@Override
public void update(IVizUpdateable component) {
// Check for null.
if (component != null) {
Vertex vertex = (Vertex) component;
// Make sure the ID is valid.
int id = vertex.getId();
// See which vertex the component matches. For whichever one
// matches, we need to update the reference, reset the length, and
// notify edge listeners.
for (int i = 0; i < 2; i++) {
if (id == vertices[i].getId()) {
updateLock.writeLock().lock();
try {
// Update the stored reference to the Vertex if its
// ID matches.
vertices[i] = vertex;
} finally {
updateLock.writeLock().unlock();
}
// Recompute the length.
updateLength();
// Notify listeners of the change.
notifyListeners();
// Break from the loop.
i = 1;
}
}
}
return;
}
