- optimize BatchNode a bit

git-svn-id: https://jmonkeyengine.googlecode.com/svn/trunk@9286 75d07b2b-3a1a-0410-a2c5-0572b91ccdca

engine/src/core/com/jme3/scene/BatchNode.java

@@ -238,9 +238,9 @@ public class BatchNode extends Node implements Savable {
                     List<Geometry> list = map.get(g.getMaterial());
                     if (list == null) {
                         //trying to compare materials with the isEqual method 
-                        for (Material mat : map.keySet()) {
-                            if (g.getMaterial().isEqual(mat)) {
-                                list = map.get(mat);
+                        for ( Map.Entry<Material, List<Geometry>> mat : map.entrySet()) {
+                            if (g.getMaterial().isEqual(mat.getKey())) {
+                                list = mat.getValue();
                             }
                         }
                     }