fixed minor findbugs problem

src/test/java/it/unibz/inf/isochrone/network/AlgorithmRuntimeTest.java

@@ -310,7 +310,7 @@ public final class AlgorithmRuntimeTest {
 			final String time = runtimeEntry.getKey();
 			final Map<String, Long> results = runtimeEntry.getValue();
 
-			double dmax = -1;
+			final double dmax;
 			try {
 				dmax = Float.parseFloat(time);
 			} catch (final NumberFormatException e) {