Interface Graph<N>

    • Method Summary

      All Methods Instance Methods Abstract Methods 
      Modifier and Type Method Description
      java.util.Set<N> adjacentNodes​(N node)
      Returns the nodes which have an incident edge in common with node in this graph.
      boolean allowsSelfLoops()
      Returns true if this graph allows self-loops (edges that connect a node to itself).
      int degree​(N node)
      Returns the count of node's incident edges, counting self-loops twice (equivalently, the number of times an edge touches node).
      java.util.Set<EndpointPair<N>> edges()
      Returns all edges in this graph.
      boolean equals​(java.lang.Object object)
      Returns true iff object is a Graph that has the same elements and the same structural relationships as those in this graph.
      boolean hasEdgeConnecting​(EndpointPair<N> endpoints)
      Returns true if there is an edge that directly connects endpoints (in the order, if any, specified by endpoints).
      boolean hasEdgeConnecting​(N nodeU, N nodeV)
      Returns true if there is an edge that directly connects nodeU to nodeV.
      int hashCode()
      Returns the hash code for this graph.
      ElementOrder<N> incidentEdgeOrder()
      Returns an ElementOrder that specifies the order of iteration for the elements of edges(), adjacentNodes(Object), predecessors(Object), successors(Object) and incidentEdges(Object).
      java.util.Set<EndpointPair<N>> incidentEdges​(N node)
      Returns the edges in this graph whose endpoints include node.
      int inDegree​(N node)
      Returns the count of node's incoming edges (equal to predecessors(node).size()) in a directed graph.
      boolean isDirected()
      Returns true if the edges in this graph are directed.
      ElementOrder<N> nodeOrder()
      Returns the order of iteration for the elements of nodes().
      java.util.Set<N> nodes()
      Returns all nodes in this graph, in the order specified by nodeOrder().
      int outDegree​(N node)
      Returns the count of node's outgoing edges (equal to successors(node).size()) in a directed graph.
      java.util.Set<N> predecessors​(N node)
      Returns all nodes in this graph adjacent to node which can be reached by traversing node's incoming edges against the direction (if any) of the edge.
      java.util.Set<N> successors​(N node)
      Returns all nodes in this graph adjacent to node which can be reached by traversing node's outgoing edges in the direction (if any) of the edge.
    • Method Detail

      • nodes

        java.util.Set<N> nodes()
        Returns all nodes in this graph, in the order specified by nodeOrder().
        Specified by:
        nodes in interface BaseGraph<N>
      • isDirected

        boolean isDirected()
        Returns true if the edges in this graph are directed. Directed edges connect a source node to a target node, while undirected edges connect a pair of nodes to each other.
        Specified by:
        isDirected in interface BaseGraph<N>
      • allowsSelfLoops

        boolean allowsSelfLoops()
        Returns true if this graph allows self-loops (edges that connect a node to itself). Attempting to add a self-loop to a graph that does not allow them will throw an IllegalArgumentException.
        Specified by:
        allowsSelfLoops in interface BaseGraph<N>
      • adjacentNodes

        java.util.Set<N> adjacentNodes​(N node)
        Returns the nodes which have an incident edge in common with node in this graph.

        This is equal to the union of predecessors(Object) and successors(Object).

        Specified by:
        adjacentNodes in interface BaseGraph<N>
        Throws:
        java.lang.IllegalArgumentException - if node is not an element of this graph
      • predecessors

        java.util.Set<N> predecessors​(N node)
        Returns all nodes in this graph adjacent to node which can be reached by traversing node's incoming edges against the direction (if any) of the edge.

        In an undirected graph, this is equivalent to adjacentNodes(Object).

        Specified by:
        predecessors in interface BaseGraph<N>
        Specified by:
        predecessors in interface PredecessorsFunction<N>
        Throws:
        java.lang.IllegalArgumentException - if node is not an element of this graph
      • successors

        java.util.Set<N> successors​(N node)
        Returns all nodes in this graph adjacent to node which can be reached by traversing node's outgoing edges in the direction (if any) of the edge.

        In an undirected graph, this is equivalent to adjacentNodes(Object).

        This is not the same as "all nodes reachable from node by following outgoing edges". For that functionality, see Graphs.reachableNodes(Graph, Object).

        Specified by:
        successors in interface BaseGraph<N>
        Specified by:
        successors in interface SuccessorsFunction<N>
        Throws:
        java.lang.IllegalArgumentException - if node is not an element of this graph
      • incidentEdges

        java.util.Set<EndpointPair<N>> incidentEdges​(N node)
        Returns the edges in this graph whose endpoints include node.

        This is equal to the union of incoming and outgoing edges.

        Specified by:
        incidentEdges in interface BaseGraph<N>
        Throws:
        java.lang.IllegalArgumentException - if node is not an element of this graph
        Since:
        24.0
      • degree

        int degree​(N node)
        Returns the count of node's incident edges, counting self-loops twice (equivalently, the number of times an edge touches node).

        For directed graphs, this is equal to inDegree(node) + outDegree(node).

        For undirected graphs, this is equal to incidentEdges(node).size() + (number of self-loops incident to node).

        If the count is greater than Integer.MAX_VALUE, returns Integer.MAX_VALUE.

        Specified by:
        degree in interface BaseGraph<N>
        Throws:
        java.lang.IllegalArgumentException - if node is not an element of this graph
      • inDegree

        int inDegree​(N node)
        Returns the count of node's incoming edges (equal to predecessors(node).size()) in a directed graph. In an undirected graph, returns the degree(Object).

        If the count is greater than Integer.MAX_VALUE, returns Integer.MAX_VALUE.

        Specified by:
        inDegree in interface BaseGraph<N>
        Throws:
        java.lang.IllegalArgumentException - if node is not an element of this graph
      • outDegree

        int outDegree​(N node)
        Returns the count of node's outgoing edges (equal to successors(node).size()) in a directed graph. In an undirected graph, returns the degree(Object).

        If the count is greater than Integer.MAX_VALUE, returns Integer.MAX_VALUE.

        Specified by:
        outDegree in interface BaseGraph<N>
        Throws:
        java.lang.IllegalArgumentException - if node is not an element of this graph
      • hasEdgeConnecting

        boolean hasEdgeConnecting​(N nodeU,
                                  N nodeV)
        Returns true if there is an edge that directly connects nodeU to nodeV. This is equivalent to nodes().contains(nodeU) && successors(nodeU).contains(nodeV).

        In an undirected graph, this is equal to hasEdgeConnecting(nodeV, nodeU).

        Specified by:
        hasEdgeConnecting in interface BaseGraph<N>
        Since:
        23.0
      • hasEdgeConnecting

        boolean hasEdgeConnecting​(EndpointPair<N> endpoints)
        Returns true if there is an edge that directly connects endpoints (in the order, if any, specified by endpoints). This is equivalent to edges().contains(endpoints).

        Unlike the other EndpointPair-accepting methods, this method does not throw if the endpoints are unordered and the graph is directed; it simply returns false. This is for consistency with the behavior of Collection.contains(Object) (which does not generally throw if the object cannot be present in the collection), and the desire to have this method's behavior be compatible with edges().contains(endpoints).

        Specified by:
        hasEdgeConnecting in interface BaseGraph<N>
        Since:
        27.1
      • equals

        boolean equals​(@CheckForNull
                       java.lang.Object object)
        Returns true iff object is a Graph that has the same elements and the same structural relationships as those in this graph.

        Thus, two graphs A and B are equal if all of the following are true:

        Graph properties besides directedness do not affect equality. For example, two graphs may be considered equal even if one allows self-loops and the other doesn't. Additionally, the order in which nodes or edges are added to the graph, and the order in which they are iterated over, are irrelevant.

        A reference implementation of this is provided by AbstractGraph.equals(Object).

        Overrides:
        equals in class java.lang.Object
      • hashCode

        int hashCode()
        Returns the hash code for this graph. The hash code of a graph is defined as the hash code of the set returned by edges().

        A reference implementation of this is provided by AbstractGraph.hashCode().

        Overrides:
        hashCode in class java.lang.Object