Improves error message in case of forgotten/wrong edge_based=true/false parameter. (graphhopper#1555)

Signed-off-by: easbar <[email protected]>

Author: easbar

core/src/main/java/com/graphhopper/routing/ch/CHAlgoFactoryDecorator.java

@@ -244,15 +244,22 @@ public RoutingAlgorithmFactory getDecoratedAlgorithmFactory(RoutingAlgorithmFact
             map.setWeighting(getDefaultWeighting());
 
         boolean edgeBased = map.getBool(Parameters.Routing.EDGE_BASED, false);
-        String entriesStr = "";
+        List<String> entriesStrs = new ArrayList<>();
+        boolean weightingMatchesButNotEdgeBased = false;
         for (PrepareContractionHierarchies p : allPreparations) {
-            if (p.isEdgeBased() == edgeBased && p.getWeighting().matches(map))
+            boolean weightingMatches = p.getWeighting().matches(map);
+            if (p.isEdgeBased() == edgeBased && weightingMatches)
                 return p;
+            else if (weightingMatches)
+                weightingMatchesButNotEdgeBased = true;
 
-            entriesStr += p.getWeighting() + "|" + (p.isEdgeBased() ? "edge" : "node") + ", ";
+            entriesStrs.add(p.getWeighting() + "|" + (p.isEdgeBased() ? "edge" : "node"));
         }
 
-        throw new IllegalArgumentException("Cannot find CH RoutingAlgorithmFactory for weighting map " + map + " in entries " + entriesStr);
+        String hint = weightingMatchesButNotEdgeBased
+                ? " The '" + Parameters.Routing.EDGE_BASED + "' url parameter is missing or does not fit the weightings. Its value was: '" + edgeBased + "'"
+                : "";
+        throw new IllegalArgumentException("Cannot find CH RoutingAlgorithmFactory for weighting map " + map + " in entries: " + entriesStrs + "." + hint);
     }
 
     public int getPreparationThreads() {