Class JSONImporter<V,​E>

  • Type Parameters:
    V - the vertex type
    E - the edge type
    All Implemented Interfaces:

    public class JSONImporter<V,​E>
    extends BaseEventDrivenImporter<V,​E>
    implements GraphImporter<V,​E>
    Imports a graph from a JSON file. Below is a small example of a graph in JSON format.
       "nodes": [
         { "id": "1" },
         { "id": "2", "label": "Node 2 label" },
         { "id": "3" }
       "edges": [
         { "source": "1", "target": "2", "weight": 2.0, "label": "Edge between 1 and 2" },
         { "source": "2", "target": "3", "weight": 3.0, "label": "Edge between 2 and 3" }

    In case the graph is weighted then the importer also reads edge weights. Otherwise edge weights are ignored. The importer also supports reading additional string attributes such as label or custom user attributes.

    The parser completely ignores elements from the input that are not related to vertices or edges of the graph. Moreover, complicated nested structures which are inside vertices or edges are simply returned as a whole. For example, in the following graph

       "nodes": [
         { "id": "1" },
         { "id": "2" }
       "edges": [
         { "source": "1", "target": "2", "points": { "x": 1.0, "y": 2.0 } }
    the points attribute of the edge is returned as a string containing {"x":1.0,"y":2.0}. The same is done for arrays or any other arbitrary nested structure.
    Dimitrios Michail
    • Constructor Detail

      • JSONImporter

        public JSONImporter()
        Construct a new importer
    • Method Detail

      • importGraph

        public void importGraph​(Graph<V,​E> graph,
                                Reader input)
        Import a graph.

        The provided graph must be able to support the features of the graph that is read. For example if the file contains self-loops then the graph provided must also support self-loops. The same for multiple edges.

        If the provided graph is a weighted graph, the importer also reads edge weights. Otherwise edge weights are ignored.

        Specified by:
        importGraph in interface GraphImporter<V,​E>
        graph - the output graph
        input - the input reader
        ImportException - in case an error occurs, such as I/O or parse error