Java tutorial
/* * Created on Oct 18, 2005 * * Copyright (c) 2005, the JUNG Project and the Regents of the University * of California * All rights reserved. * * This software is open-source under the BSD license; see either * "license.txt" or * http://jung.sourceforge.net/license.txt for a description. */ package edu.uci.ics.jung.graph; import java.util.Comparator; import java.util.Map; import java.util.Set; import java.util.TreeMap; import java.util.TreeSet; import org.apache.commons.collections15.Factory; import org.apache.commons.collections15.comparators.ComparableComparator; import edu.uci.ics.jung.graph.util.Pair; /** * An implementation of <code>Graph</code> that is suitable for sparse graphs, * orders its vertex and edge collections according to either specified <code>Comparator</code> * instances or the natural ordering of their elements, and permits directed, undirected, * and parallel edges. * * @author Joshua O'Madadhain */ @SuppressWarnings("serial") public class SortedSparseMultigraph<V, E> extends OrderedSparseMultigraph<V, E> implements MultiGraph<V, E> { /** * Returns a {@code Factory} that creates an instance of this graph type. * @param <V> the vertex type for the graph factory * @param <E> the edge type for the graph factory */ public static <V, E> Factory<Graph<V, E>> getFactory() { return new Factory<Graph<V, E>>() { public Graph<V, E> create() { return new SortedSparseMultigraph<V, E>(); } }; } /** * <code>Comparator</code> used in ordering vertices. Defaults to <code>util.ComparableComparator</code> * if no comparators are specified in the constructor. */ protected Comparator<V> vertex_comparator; /** * <code>Comparator</code> used in ordering edges. Defaults to <code>util.ComparableComparator</code> * if no comparators are specified in the constructor. */ protected Comparator<E> edge_comparator; /** * Creates a new instance which sorts its vertices and edges according to the * specified {@code Comparator}s. */ public SortedSparseMultigraph(Comparator<V> vertex_comparator, Comparator<E> edge_comparator) { this.vertex_comparator = vertex_comparator; this.edge_comparator = edge_comparator; vertices = new TreeMap<V, Pair<Set<E>>>(vertex_comparator); edges = new TreeMap<E, Pair<V>>(edge_comparator); directedEdges = new TreeSet<E>(edge_comparator); } /** * Creates a new instance which sorts its vertices and edges according to * their natural ordering. */ @SuppressWarnings("unchecked") public SortedSparseMultigraph() { this(new ComparableComparator(), new ComparableComparator()); } /** * Provides a new {@code Comparator} to be used in sorting the vertices. * @param vertex_comparator the comparator that defines the new ordering */ public void setVertexComparator(Comparator<V> vertex_comparator) { this.vertex_comparator = vertex_comparator; Map<V, Pair<Set<E>>> tmp_vertices = new TreeMap<V, Pair<Set<E>>>(vertex_comparator); for (Map.Entry<V, Pair<Set<E>>> entry : vertices.entrySet()) tmp_vertices.put(entry.getKey(), entry.getValue()); this.vertices = tmp_vertices; } @Override public boolean addVertex(V vertex) { if (vertex == null) { throw new IllegalArgumentException("vertex may not be null"); } if (!containsVertex(vertex)) { vertices.put(vertex, new Pair<Set<E>>(new TreeSet<E>(edge_comparator), new TreeSet<E>(edge_comparator))); return true; } else { return false; } } }