Android, big listeners, and performance/maintainability

Question

I have a pretty big listener interface for an Android chat app. I also have an adapter for the listener, with empty methods.

Here it is:

public static interface Listener {

    public void connectionStarted(Server server);

    public void onConnected(Server server);

    public void onDisconnected(Server server, DisconnectType type);

    public void onReconnectStarting(Server server, int reconnectAttempt);

    public void onReconnectStarted(Server server, int reconnectAttempt);

    public void onReconnectEnded(Server server, int numReconnects);

    public void onReconnectCanceled(Server server);

    public void onRegistered(Server server);

    public void onMessage(Server server, Message msg);

    public void onQueryMessage(Server server, User user, String hostmask, String msg);

    public void joinedChannel(Server server, Channel channel);

    public void partedChannel(Server server, Channel channel);

    public void onNames(Server server, List<String> batch);

    public void onNamesEnd(Server server);

    public void onListStart(Server server);

    public void onList(Server server, ListEntry entry);

    public void onListEnd(Server server);

    public void onIsOn(Server server, List<String> nicks);

    public void onWho(Server server, WhoData data);

    public void onWhoFailed(Server server, String nick);

    public void onWhoIs(Server server, WhoisData data);

    public void onWhoIsFailed(Server server, String nick);

    public void onWhoWas(Server server, WhoWasData data);

    public void onWhoWasFailed(Server server, String nick);

    public void onCTCPVersion(Server server, String nick, String hostmask, String version);

    public void onCTCPPing(Server server, String nick, String hostmask, String ping);

    public void onCTCPTime(Server server, String nick, String hostmask, String time);

    public void onNotice(Server server, String nick, String hostmask, String message);

    public void onNickInUse(Server server, String nick);

    public void myNickChanged(Server server, String oldNick, String newNick, boolean onRegistered);

    public void onSASLAuthenticationStarted(Server server);
}

For example, if you look at the listener, it has an onMessage()-method, which is called quite a lot (if the user is in many chat channels). And these "no-op" method calls get redirected to lots and lots of completely unrelated listeners.

I'm pretty sure that Oracle's JVM would be smart enough to optimize away all these no-op method calls, but I have no idea if this is the case for the Dalvik VM.

Do you think I should refactor the listener into smaller interfaces (e.g. ConnectionListener, MessageListener, JoinListener and so on), from a performance and maintainability point of view?

whats wrong with dozen (or two) of methods in the interface ? — pskink, Jan 12 '14 at 14:04
I definitely think you should split this into multiple listeners. There seems to be a lot of different things going on here and if you have no-op calls that's a big indicator things are listening for things that don't concern them. You might find Googling the "single responsibility principle" useful — Alex Curran, Jan 12 '14 at 14:23

Android, big listeners, and performance/maintainability

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