前言:我知道有高质量的图形API可用。我有兴趣写自己的自我完善。Java:添加节点到图形错误
这是我的函数添加节点:
public void addNode(Vertex v, Collection<Edge> neighbors) {
int originalSize = size();
if (head == null) {
head = v;
}
else {
Collection<Edge> inEdges = new ArrayList<Edge>();
inEdges.addAll(neighbors);
traverseGraphToAdd(head, inEdges, v);
}
assert originalSize + 1 == size() :
String.format("adding operation failed. original size: %d, current size: %d", originalSize, size());
}
private void traverseGraphToAdd(Vertex start, Collection<Edge> inEdges, Vertex toAdd) {
Iterator<Edge> iter = inEdges.iterator();
Edge e;
while (iter.hasNext()) {
e = iter.next();
if (e.getSource().equals(start)) {
start.addEdge(e);
iter.remove();
}
else if (! directionalEdges && e.getSink().equals(start)) {
start.addEdge(e);
iter.remove();
}
}
if (inEdges.size() > 0) { //otherwise there's no point in continuing to search
for (Edge arc : start.getOutEdges()) {
traverseGraphToAdd(arc.getSink(), inEdges, toAdd);
}
}
}
大小和它的依赖:
public int size() {
int count = 0;
if (head == null) {
return 0;
}
else {
count = countNodes(head);
}
clearVisited();
return count;
}
private int countNodes(Vertex start) {
int result = 1;
start.setVisited(true);
for (Edge e: start.getOutEdges()) {
if (! e.getSink().isVisited()) {
result += countNodes(e.getSink());
}
}
return result;
}
private void clearVisited() {
if (head != null) {
clearNode(head);
}
}
private void clearNode(Vertex start) {
start.setVisited(false);
for (Edge e: start.getOutEdges()) {
if (e.getSink().isVisited()) {
clearNode(e.getSink());
}
}
}
边缘分类:
public Edge(Vertex source, Vertex sink, int weight) {
this.source = source;
this.sink = sink;
this.weight = weight;
}
以下调用工作:
g.addNode(ftw, new HashSet<Edge>()); //first node - empty edges
g.addNode(odp, Arrays.asList(new Edge(ftw, odp, 3))); //link new node to one already in the graph
这不:
g.addNode(tlt, Arrays.asList(new Edge(tlt, ftw, 2)));
在这其中,边缘构造函数的第一个参数是不已经在图中的节点。我尝试用下面的(从上面重复),以纠正这种在ADDNODE:
if (e.getSource().equals(start)) { /*... */ }
else if (! directionalEdges && e.getSink().equals(start)) { /*... */ }
directionalEdges
是一类字段确定此图形是否是定向的或不。
然而,这会导致的断言错误:
Exception in thread "main" java.lang.AssertionError: adding operation failed. original size: 1, current size: 1
这到底是怎么回事?
addNode()中调用的size()方法的外观如何?我没有在traverseGraphToAdd()中看到任何你将对象放入集合的地方。 – uckelman 2009-11-16 23:14:27
你有调试器吗?我强烈建议从那里开始。 – StevenWilkins 2009-11-16 23:19:31
我一直在Eclipse中经历它,似乎无法弄清楚。 – 2009-11-16 23:20:38