Remove duplicate registration checks, and some minor code cleanup (#60)

Author: PaintNinja

src/main/java/net/minecraftforge/eventbus/ASMEventHandler.java

@@ -13,7 +13,7 @@ public class ASMEventHandler implements IEventListener {
     private final IEventListenerFactory factory;
     private final IEventListener handler;
     private final SubscribeEvent subInfo;
-    private String readable;
+    private final String readable;
     private Type filter = null;
 
     public ASMEventHandler(IEventListenerFactory factory, Object target, Method method, boolean isGeneric) throws IllegalAccessException, InstantiationException, NoSuchMethodException, InvocationTargetException, ClassNotFoundException {

src/main/java/net/minecraftforge/eventbus/EventBus.java

@@ -24,10 +24,10 @@
 public class EventBus implements IEventExceptionHandler, IEventBus {
     private static final Logger LOGGER = LogManager.getLogger();
     private static final boolean checkTypesOnDispatchProperty = Boolean.parseBoolean(System.getProperty("eventbus.checkTypesOnDispatch", "false"));
-    private static AtomicInteger maxID = new AtomicInteger(0);
+    private static final AtomicInteger maxID = new AtomicInteger(0);
     private final boolean trackPhases;
 
-    private ConcurrentHashMap<Object, List<IEventListener>> listeners = new ConcurrentHashMap<>();
+    private final ConcurrentHashMap<Object, List<IEventListener>> listeners = new ConcurrentHashMap<>();
     private final int busID = maxID.getAndIncrement();
     private final IEventExceptionHandler exceptionHandler;
     private volatile boolean shutdown = false;
@@ -161,34 +161,32 @@ private void registerListener(final Object target, final Method method, final Me
 
     private static final Predicate<Event> checkCancelled = e -> !e.isCanceled();
     @SuppressWarnings("unchecked")
-    private <T extends Event> Predicate<T> passCancelled(boolean ignored) {
+    private static <T extends Event> Predicate<T> passCancelled(boolean ignored) {
         return ignored ? null : (Predicate<T>)checkCancelled;
     }
 
-    private <T extends GenericEvent<? extends F>, F> Predicate<T> passGenericFilter(Class<F> type, boolean ignored) {
+    private static <T extends GenericEvent<? extends F>, F> Predicate<T> passGenericFilter(Class<F> type, boolean ignored) {
         if (ignored)
             return e -> e.getGenericType() == type;
         return e -> e.getGenericType() == type && !e.isCanceled();
     }
 
-    private void checkNotGeneric(final Consumer<? extends Event> consumer) {
+    private static void checkNotGeneric(final Consumer<? extends Event> consumer) {
         checkNotGeneric(getEventClass(consumer));
     }
 
-    private void checkNotGeneric(final Class<? extends Event> eventType) {
+    private static void checkNotGeneric(final Class<? extends Event> eventType) {
         if (GenericEvent.class.isAssignableFrom(eventType))
             throw new IllegalArgumentException("Cannot register a generic event listener with addListener, use addGenericListener");
     }
 
     @Override
     public <T extends Event> void addListener(final Consumer<T> consumer) {
-        checkNotGeneric(consumer);
         addListener(EventPriority.NORMAL, consumer);
     }
 
     @Override
     public <T extends Event> void addListener(final EventPriority priority, final Consumer<T> consumer) {
-        checkNotGeneric(consumer);
         addListener(priority, false, consumer);
     }
 
@@ -225,7 +223,7 @@ public <T extends GenericEvent<? extends F>, F> void addGenericListener(final Cl
     }
 
     @SuppressWarnings("unchecked")
-    private <T extends Event> Class<T> getEventClass(Consumer<T> consumer) {
+    private static <T extends Event> Class<T> getEventClass(Consumer<T> consumer) {
         final Class<T> eventClass = (Class<T>) TypeResolver.resolveRawArgument(Consumer.class, consumer.getClass());
         if ((Class<?>)eventClass == TypeResolver.Unknown.class) {
             LOGGER.error(EVENTBUS, "Failed to resolve handler for \"{}\"", consumer.toString());
@@ -252,7 +250,7 @@ private <T extends Event> void addListener(final EventPriority priority, final P
     }
 
     @SuppressWarnings("unchecked")
-    private <T extends Event> void doCastFilter(final Predicate<? super T> filter, final Class<T> eventClass, final Consumer<T> consumer, final Event e) {
+    private static <T extends Event> void doCastFilter(final Predicate<? super T> filter, final Class<T> eventClass, final Consumer<T> consumer, final Event e) {
         T cast = (T)e;
         if (filter == null || filter.test(cast))
             consumer.accept(cast);

src/main/java/net/minecraftforge/eventbus/ListenerList.java

@@ -17,11 +17,11 @@
 
 
 public class ListenerList {
-    private static List<ListenerList> allLists = new ArrayList<>();
+    private static final List<ListenerList> allLists = new ArrayList<>();
     private static int maxSize = 0;
 
     @Nullable
-    private ListenerList parent;
+    private final ListenerList parent;
     private ListenerListInst[] lists = new ListenerListInst[0];
 
     public ListenerList() {
@@ -97,13 +97,13 @@ public static synchronized void unregisterAll(int id, IEventListener listener) {
             list.unregister(id, listener);
     }
 
-    private class ListenerListInst {
+    private static class ListenerListInst {
         private boolean rebuild = true;
         private AtomicReference<IEventListener[]> listeners = new AtomicReference<>();
-        private ArrayList<ArrayList<IEventListener>> priorities;
+        private final ArrayList<ArrayList<IEventListener>> priorities;
         private ListenerListInst parent;
         private List<ListenerListInst> children;
-        private Semaphore writeLock = new Semaphore(1, true);
+        private final Semaphore writeLock = new Semaphore(1, true);
 
         private ListenerListInst() {
             int count = EventPriority.values().length;