How to Quickstart graphhopper with my own graph - The Basics

Question

After two hard days getting through the unit tests and snippets of graphhopper on GitHub and the JavaDocs, thinking that I might be able to put all together in a very basic java app, I have to come to the conclusion, that I am not able :(

All I want to do is:

1. Build a graph
2. Init graphhopper and configure it correctly
3. Load the graph
4. Route on it

Thats my code so far:

package javaapplication1;

import com.graphhopper.*;
import com.graphhopper.routing.util.EncodingManager;
import com.graphhopper.storage.GraphBuilder;
import com.graphhopper.storage.GraphStorage;

public class JavaApplication1 {

    protected static String location = "./tmp/graphstorage";
    protected static String defaultGraph = "./tmp/graphstorage/default";  

    private static final EncodingManager encodingManager = new EncodingManager("CAR");

    public static GraphStorage createGraph() {

        GraphStorage graph = new GraphBuilder(encodingManager).setLocation(location).create();
        graph.setNode(0, 42, 10);
        graph.setNode(1, 42.1, 10.1);
        graph.setNode(2, 42.1, 10.2);
        graph.setNode(3, 42, 10.4);
        graph.setNode(4, 41.9, 10.2);

        graph.edge(0, 1, 10, true);
        graph.edge(1, 2, 10, false);
        graph.edge(2, 3, 10, true);
        graph.edge(0, 4, 40, true);
        graph.edge(4, 3, 40, true);

        return graph;
    }

    public static void main(String[] args) {

        double fromLat = 42;
        double fromLon = 10.4;
        double toLat = 42;
        double toLon = 10;

        GraphStorage gs = createGraph();

        GraphHopperAPI instance = new GraphHopper()
            .setEncodingManager(encodingManager)
            .setGraphHopperLocation(location)
            .disableCHShortcuts();

        GraphHopper hopper = (GraphHopper) instance;
        //hopper.setGraph(createGraph()); // protected because only for testing?

        hopper.load(location);

        GHResponse ph = hopper.route(new GHRequest(fromLat, fromLon, toLat, toLon));
        if(ph.isFound()) {
            System.out.println(ph.getDistance());
            System.out.println(ph.getPoints().getSize());
        } else {
            System.out.println("No Route found!");
        }   
    }
}

Java says: "Exception in thread "main" java.lang.IllegalStateException: Call load or importOrLoad before routing". But I am calling .load() on hopper, which unfortunately returns 'false', but I am not able to figure out why.

My goal for this thread is to provide a very basic working code example of the GH Components and how to wire them up to solve the use case "Route on a graph, not loaded from OSM".

Answer 1

If you don't want to use OSM as data source you have to options:

1. Using the low level API via copy and pasting the code under GraphHopper.route. No need to reuse the GraphHopper class. But this is probably harder.
2. Do MyGraphHopper extends GraphHopper and overload the necessary methods. Be sure you set the graph before the 'postProcessing' method is called. Which e.g. creates the shortcuts and builds the locationIndex.

BTW: in master GraphHopper.setGraph is public?