add helper to easily get random routes and jobs from collection

jsprit-core/src/main/java/jsprit/core/util/RandomUtils.java

@@ -0,0 +1,34 @@
+package jsprit.core.util;
+
+import jsprit.core.problem.job.Job;
+import jsprit.core.problem.solution.route.VehicleRoute;
+
+import java.util.Collection;
+import java.util.Random;
+
+/**
+ * Created by schroeder on 14/01/15.
+ */
+public class RandomUtils {
+
+    public static VehicleRoute nextRoute(Collection<VehicleRoute> routes, Random random){
+        int randomIndex = random.nextInt(routes.size());
+        int count = 0;
+        for(VehicleRoute route : routes){
+            if(count <= randomIndex) return route;
+            count++;
+        }
+        return null;
+    }
+
+    public static Job nextJob(Collection<Job> jobs, Random random){
+        int randomIndex = random.nextInt(jobs.size());
+        int count = 0;
+        for(Job job : jobs){
+            if(count <= randomIndex) return job;
+            count++;
+        }
+        return null;
+    }
+
+}