description:
i have a hashmap with objects (class Child), i wonder if when i get the object from the hashmap is by reference and if i update it, will change inside the hashmap. if not, how can i update it.

code:
HashMap Parent = new HashMap();    // the hashmap
Child child = (Child) Parent.get(id);      // geting the object
child.update(school,grade);                 // running objects update function

result:
gives no error, but doesn't update the hasmap.

help needed, thanks

edit: if i put it back in, will be duplicated?