/**
* Dijkstra doesn't allow negative edge weights so throw an exception if one was found.
*
* @throws IllegalArgumentException if the graph contains negative weights
*/
private void checkForNegativeWeights() {
for (Edge e : graph.getEdges()) {
if (e.getWeight() < 0) {
throw new IllegalArgumentException("graph contains negative weights!");
}
}
}
private void executeDijkstra() {
// determine minimum distance vertex and add it to the path.
while (!this.priorityQueue.isEmpty()) {
Vertex vertex = this.priorityQueue.extractMin();
for (Edge e : graph.getIncidentEdgesOf(vertex)) {
relax(vertex, e.getVertexB(), e.getWeight(), dist, pred);
}
}
}
/**
* Set every distance to int.max and sets the start vertex by setting distance to 0
*
* @throws IllegalArgumentException if the graph contains negative weights
* @param start
*/
private void init(Vertex start) throws IllegalArgumentException {
checkForNegativeWeights();
for (Vertex v : graph.getVertices()) {
dist.put(v, Double.MAX_VALUE);
}
// sets start Vertex by setting distance to 0
dist.put(start, 0.0);
}