changed session to a singleton method.

src/main/java/controllers/Main.java

@@ -40,7 +40,7 @@ public class Main extends Application {
         base = root;
         baseController = (BaseController) loader.getController();
         baseController.setParent(this);
-        this.session = new Session();
+        this.session = Session.session;
         try{
             DataManagerSerialiser dataManagerSerialiser = new DataManagerSerialiser();
             DataManager dataManager = dataManagerSerialiser.load();

src/main/java/model/Session.java

@@ -7,8 +7,10 @@ public class Session {
 
     private String userCode;//this is like fwy13
     DataManager dataManager;
+    public static Session session = new Session();
 
     public Session(){
+        session = this;
         dataManager = new DataManager();
     }