About your signature? Since a Map/List/Set are pointers and only a reference to the object therefore if you edit the object outside the map then it'll be reflected in the Map/List/Set etc... So when the player logs out and the object is nulled, it'll be null in the Map/List/Set? Unless you stored your own Player object in which case their stupid :D
when you null the objecxt, it wont reflect inside the map, consider doing this example: [syntax=java] Map map = new HashMap<String,String> String value = "b"; String key = "a"; map.put(key,value); value = null; System.out.println(map.get(key));[/syntax]It will print out "b", even the value is nulled out
Ok well it appears I have been mislead about some information about Maps :( It does appear that Maps are not pointers then :( I'll have a word to Afforess about this since he told me