How to use

NetworkConnections

in

com.google.common.graph

if (!allowsParallelEdges()) {
 checkArgument(
   !(connectionsU != null && connectionsU.successors().contains(nodeV)),
   PARALLEL_EDGES_NOT_ALLOWED,
   nodeU,
 connectionsU = addNodeInternal(nodeU);
connectionsU.addOutEdge(edge, nodeV);
NetworkConnections<N, E> connectionsV = nodeConnections.get(nodeV);
if (connectionsV == null) {
 connectionsV = addNodeInternal(nodeV);
connectionsV.addInEdge(edge, nodeU, isSelfLoop);
edgeToReferenceNode.put(edge, nodeU);
return true;

@Override
@CanIgnoreReturnValue
public boolean removeEdge(E edge) {
 checkNotNull(edge, "edge");
 N nodeU = edgeToReferenceNode.get(edge);
 if (nodeU == null) {
  return false;
 }
 NetworkConnections<N, E> connectionsU = nodeConnections.get(nodeU);
 N nodeV = connectionsU.adjacentNode(edge);
 NetworkConnections<N, E> connectionsV = nodeConnections.get(nodeV);
 connectionsU.removeOutEdge(edge);
 connectionsV.removeInEdge(edge, allowsSelfLoops() && nodeU.equals(nodeV));
 edgeToReferenceNode.remove(edge);
 return true;
}

@Override
public Set<N> adjacentNodes(N node) {
 return checkedConnections(node).adjacentNodes();
}

@Override
public Set<E> incidentEdges(N node) {
 return checkedConnections(node).incidentEdges();
}

@Override
public Set<E> edgesConnecting(N nodeU, N nodeV) {
 NetworkConnections<N, E> connectionsU = checkedConnections(nodeU);
 if (!allowsSelfLoops && nodeU == nodeV) { // just an optimization, only check reference equality
  return ImmutableSet.of();
 }
 checkArgument(containsNode(nodeV), NODE_NOT_IN_GRAPH, nodeV);
 return connectionsU.edgesConnecting(nodeV);
}

@Override
public EndpointPair<N> incidentNodes(E edge) {
 N nodeU = checkedReferenceNode(edge);
 N nodeV = nodeConnections.get(nodeU).adjacentNode(edge);
 return EndpointPair.of(this, nodeU, nodeV);
}

@Override
public Set<E> outEdges(N node) {
 return checkedConnections(node).outEdges();
}

@Override
public Set<N> predecessors(N node) {
 return checkedConnections(node).predecessors();
}

@Override
public Set<E> inEdges(N node) {
 return checkedConnections(node).inEdges();
}

@Override
public Set<E> incidentEdges(N node) {
 return checkedConnections(node).incidentEdges();
}

@Override
public Set<E> edgesConnecting(N nodeU, N nodeV) {
 NetworkConnections<N, E> connectionsU = checkedConnections(nodeU);
 if (!allowsSelfLoops && nodeU == nodeV) { // just an optimization, only check reference equality
  return ImmutableSet.of();
 }
 checkArgument(containsNode(nodeV), NODE_NOT_IN_GRAPH, nodeV);
 return connectionsU.edgesConnecting(nodeV);
}

@Override
public EndpointPair<N> incidentNodes(E edge) {
 N nodeU = checkedReferenceNode(edge);
 N nodeV = nodeConnections.get(nodeU).adjacentNode(edge);
 return EndpointPair.of(this, nodeU, nodeV);
}

@Override
public Set<E> outEdges(N node) {
 return checkedConnections(node).outEdges();
}

@Override
public Set<N> predecessors(N node) {
 return checkedConnections(node).predecessors();
}

@Override
public Set<E> inEdges(N node) {
 return checkedConnections(node).inEdges();
}

@Override
@CanIgnoreReturnValue
public boolean removeEdge(E edge) {
 checkNotNull(edge, "edge");
 N nodeU = edgeToReferenceNode.get(edge);
 if (nodeU == null) {
  return false;
 }
 NetworkConnections<N, E> connectionsU = nodeConnections.get(nodeU);
 N nodeV = connectionsU.adjacentNode(edge);
 NetworkConnections<N, E> connectionsV = nodeConnections.get(nodeV);
 connectionsU.removeOutEdge(edge);
 connectionsV.removeInEdge(edge, allowsSelfLoops() && nodeU.equals(nodeV));
 edgeToReferenceNode.remove(edge);
 return true;
}

if (!allowsParallelEdges()) {
 checkArgument(
   !(connectionsU != null && connectionsU.successors().contains(nodeV)),
   PARALLEL_EDGES_NOT_ALLOWED,
   nodeU,
 connectionsU = addNodeInternal(nodeU);
connectionsU.addOutEdge(edge, nodeV);
NetworkConnections<N, E> connectionsV = nodeConnections.get(nodeV);
if (connectionsV == null) {
 connectionsV = addNodeInternal(nodeV);
connectionsV.addInEdge(edge, nodeU, isSelfLoop);
edgeToReferenceNode.put(edge, nodeU);
return true;

@Override
public Set<E> incidentEdges(N node) {
 return checkedConnections(node).incidentEdges();
}

@Override
public Set<E> edgesConnecting(N nodeU, N nodeV) {
 NetworkConnections<N, E> connectionsU = checkedConnections(nodeU);
 if (!allowsSelfLoops && nodeU == nodeV) { // just an optimization, only check reference equality
  return ImmutableSet.of();
 }
 checkArgument(containsNode(nodeV), NODE_NOT_IN_GRAPH, nodeV);
 return connectionsU.edgesConnecting(nodeV);
}

@Override
public EndpointPair<N> incidentNodes(E edge) {
 N nodeU = checkedReferenceNode(edge);
 N nodeV = nodeConnections.get(nodeU).adjacentNode(edge);
 return EndpointPair.of(this, nodeU, nodeV);
}