Use HashMap or something similar to store lists of objects

Question

I have several classes that all extend a certain class. I want to use a HashMap or something similar to hold an ArrayList for each of those classes, as kind of shown below.

HashMap<? extends MasterClass, ArrayList<? extends MasterClass>>

I want to call get with the extended class. This should return the ArrayList of that class. Is this possible?

get(Class);

Answer 1

You need to have Class<? extends MasterClass> Class<? extends MasterClass> as key of your map:

Map<Class<? extends MasterClass>, List<? extends MasterClass>> map 
    = new HashMap<Class<? extends MasterClass>, List<? extends MasterClass>>();