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POEncapsulated event handling with Enums
 

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    <p>My Application Layer/View has a event dispatching system aka blackboard. In it listeners are stored by a hashmap with keys being event types implemented as an enum EventType and values being the listener references listening to this event type. E.g. a model object is listening to event type "LOCAL_PLAYER_INPUT", blackboard processes and notifies the player since player implements EventHandler interface.</p> <p>I would like to decouple my model further by implementing a standalone blackboard for model. It would then be added as a listener to the application layer blackboard since application layer is getting I/O from keyboard or touch. Model blackboard would itself delegate events further then. For this I wanted to create an enum hierachy where the event is categorized in this manner:</p> <pre><code>MODEL.LOCAL.PLAYER_INPUT </code></pre> <p>Model would be registered as listener in view blackboard only by passing MODEL like this: </p> <pre><code>addListener(model.blackboard, MODEL); //Types: (EventHandler, EventType) </code></pre> <p>By combining interfaces with enums I achieved, that I can write eventtypes like MODEL.X.Y but it won't be accepted by addListener although MODEL is implementing EventType interface. </p> <p><strong>What should I do?</strong></p> <p><em>EDIT: Some more code</em></p> <p>addListener Method:</p> <pre><code> public void addListener(EventHandler handler, EventType eventType) { getListener(eventType).add(handler);} private Array&lt;EventHandler&gt; getListener(EventType eventType) { if(map.containsKey(eventType)) return map.get(eventType); else { Array&lt;EventHandler&gt; tmp = new Array&lt;EventHandler&gt;(false, 1, EventHandler.class); map.put(eventType, tmp); return tmp; } } </code></pre> <p>Enums:</p> <pre><code>public interface WL extends EventType { public static enum LOCAL { PLAYER_INPUT, NPC_INPUT } </code></pre> <p>}</p> <p>GameEvent:</p> <pre><code> public GameEvent(EventType eventType, Object message) { this.eventType = eventType; this.message = message; timeStamp = System.currentTimeMillis(); } </code></pre>
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    1. USAlex Goldstein
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    1. COSince your keys are enums, you should consider using an `EnumMap`. Although I believe this is not really performance critical here
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    2. COThat is a nice tip, I will implement it, thanks!
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      1. USAlex Goldstein
    3. COSome more code would be helpful. How do your enum(s) look like, what's the compiler complaining about?
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      1. USlost
 

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