avoid returning always the same vehicle by randomizing type container

jsprit-core/src/main/java/jsprit/core/algorithm/box/Jsprit.java

@@ -313,7 +313,11 @@ public class Jsprit {
         VehicleFleetManager fm;
         if (vrp.getFleetSize().equals(VehicleRoutingProblem.FleetSize.INFINITE)) {
             fm = new InfiniteFleetManagerFactory(vrp.getVehicles()).createFleetManager();
-        } else fm = new FiniteFleetManagerFactory(vrp.getVehicles()).createFleetManager();
+        } else {
+            FiniteFleetManagerFactory finiteFleetManagerFactory = new FiniteFleetManagerFactory(vrp.getVehicles());
+            finiteFleetManagerFactory.setRandom(random);
+            fm = finiteFleetManagerFactory.createFleetManager();
+        }
 
         if (stateManager == null) {
             stateManager = new StateManager(vrp);

jsprit-core/src/main/java/jsprit/core/problem/vehicle/FiniteFleetManagerFactory.java

@@ -16,7 +16,10 @@
  ******************************************************************************/
 package jsprit.core.problem.vehicle;
 
+import jsprit.core.util.RandomNumberGeneration;
+
 import java.util.Collection;
+import java.util.Random;
 
 /**
  * Factory that creates a finite fleetmanager.
@@ -27,6 +30,8 @@ public class FiniteFleetManagerFactory implements VehicleFleetManagerFactory {
 
     private Collection<Vehicle> vehicles;
 
+    private Random random = RandomNumberGeneration.getRandom();
+
     /**
      * Constucts the factory.
      *
@@ -37,6 +42,10 @@ public class FiniteFleetManagerFactory implements VehicleFleetManagerFactory {
         this.vehicles = vehicles;
     }
 
+    public void setRandom(Random random) {
+        this.random = random;
+    }
+
     /**
      * Creates the finite fleetmanager.
      *
@@ -47,7 +56,9 @@ public class FiniteFleetManagerFactory implements VehicleFleetManagerFactory {
     public VehicleFleetManager createFleetManager() {
         if (vehicles == null) throw new IllegalStateException("vehicles is null. this must not be.");
         if (vehicles.isEmpty()) throw new IllegalStateException("vehicle-collection is empty. this must not be");
-        return new VehicleFleetManagerImpl(vehicles);
+        VehicleFleetManagerImpl vehicleFleetManager = new VehicleFleetManagerImpl(vehicles);
+        vehicleFleetManager.setRandom(random);
+        return vehicleFleetManager;
     }
 
 }

jsprit-core/src/main/java/jsprit/core/problem/vehicle/VehicleFleetManagerImpl.java

@@ -17,12 +17,14 @@
 package jsprit.core.problem.vehicle;
 
 import jsprit.core.problem.vehicle.VehicleImpl.NoVehicle;
+import jsprit.core.util.RandomNumberGeneration;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
+import java.util.Random;
 
 
 class VehicleFleetManagerImpl implements VehicleFleetManager {
@@ -35,11 +37,17 @@ class VehicleFleetManagerImpl implements VehicleFleetManager {
 
         private ArrayList<Vehicle> vehicleList;
 
+        private Random random = RandomNumberGeneration.getRandom();
+
         public TypeContainer() {
             super();
             vehicleList = new ArrayList<Vehicle>();
         }
 
+        public void setRandom(Random random) {
+            this.random = random;
+        }
+
         void add(Vehicle vehicle) {
             if (vehicleList.contains(vehicle)) {
                 throw new IllegalStateException("cannot add vehicle twice " + vehicle.getId());
@@ -52,7 +60,8 @@ class VehicleFleetManagerImpl implements VehicleFleetManager {
         }
 
         public Vehicle getVehicle() {
-            return vehicleList.get(vehicleList.size()-1);
+            int randomIndex = random.nextInt(vehicleList.size());
+            return vehicleList.get(randomIndex);
         }
 
         public boolean isEmpty() {
@@ -71,6 +80,8 @@ class VehicleFleetManagerImpl implements VehicleFleetManager {
 
     private Vehicle[] vehicleArr;
 
+    private Random random = RandomNumberGeneration.getRandom();
+
     public VehicleFleetManagerImpl(Collection<Vehicle> vehicles) {
         super();
         this.vehicles = vehicles;
@@ -81,6 +92,10 @@ class VehicleFleetManagerImpl implements VehicleFleetManager {
         logger.debug("initialise {}",this);
     }
 
+    public void setRandom(Random random) {
+        this.random = random;
+    }
+
     @Override
     public String toString() {
         return "[name=finiteVehicles]";
@@ -95,7 +110,9 @@ class VehicleFleetManagerImpl implements VehicleFleetManager {
         }
         vehicleTypes = new TypeContainer[maxTypeIndex+1];
         for(int i=0;i< vehicleTypes.length;i++){
-            vehicleTypes[i] = new TypeContainer();
+            TypeContainer typeContainer = new TypeContainer();
+            typeContainer.setRandom(random);
+            vehicleTypes[i] = typeContainer;
         }
         for (Vehicle v : vehicles) {
             vehicleArr[v.getIndex()]=v;