CODEWITHSUNDEEP
javaclassinheritance
Elite_Dragon1337
Elite_Dragon1337

Reputation: 348

Comparing class types with inheritance

For my project, I have a HashMap with Class<?> as key and MyClass as value.

Map<Class<?>, MyClass> map = new HashMap<Class<?>, MyClass>();

As an example, I put in some values:

map.put(EntityDamageEvent.getClass(), new MyClass());

This is the inheritance tree for this key:

class EntityDamageByEntityEvent extends EntityDamageEvent
class EntityDamageEvent extends EntityEvent
class EntityEvent extends Event

The problem arises when I try to get a value from the map, but the key happens to be a subclass of the key I'm actually trying to use:

void doSomething() {
    EntityDamageByEntityEvent event = new EntityDamageByEntityEvent();

    post(event); //This returns null
}

MyClass post(Event event) {
    return map.get(event.getClass());
}

Object.getclass() gives me the subclass, and not the class that I want.

How should I tackle this problem? Thanks

Upvotes: 2

Views: 138

Answers (4)

Elite_Dragon1337
Elite_Dragon1337

Reputation: 348

Thanks for the help guys, I have done this:

public void post(Event event, Class<?> type) {}

this.post(new EntityDamageByEntityEvent(), EntityDamage.class);

Upvotes: 0

Sage
Sage

Reputation: 15418

A different idea:

Use the HashMap<String, MyClass> where the key is to be inserted with the Class's fully qualified name: SubClass.class.getName(). While retrieving, you can use Class.forName(key) to find the correct class.

Upvotes: 0

Javier
Javier

Reputation: 12398

Iterate over the subclass ancestors, until you find someone that is in the map.

for (Class<T> klass = event.getClass(); klass!=null; klass=klass.getSuperclass()) {
 MyClass c = map.get(klass);
 if (c!=null) return c;
}
return null;

Upvotes: 2

Evorlor
Evorlor

Reputation: 7559

Replace

EntityDamageByEntityEvent event = new EntityDamageByEntityEvent();

with

Event event = new Event();

Upvotes: 0

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