Merge pull request #280 from Phoenix-Starlight/refactor/validate-even…

…t-listeners
discord-jar · Mar 22, 2024 · b0285cc · b0285cc
2 parents d6d0923 + 47b5a99
commit b0285cc
Showing 1 changed file with 9 additions and 1 deletion.
diff --git a/src/main/java/com/seailz/discordjar/events/EventDispatcher.java b/src/main/java/com/seailz/discordjar/events/EventDispatcher.java
@@ -55,7 +55,15 @@ public void addListener(DiscordListener... listeners) {
         for (DiscordListener listener : listeners) {
             for (Method method : listener.getClass().getMethods()) {
                 if (method.isAnnotationPresent(EventMethod.class)) {
-                    Class<? extends Event> eventType = (Class<? extends Event>) method.getParameterTypes()[0];
+                    Class<?> maybeEventType = method.getParameterTypes()[0];
+
+                    if (!Event.class.isAssignableFrom(maybeEventType))
+                        throw new IllegalArgumentException(String.format("%s first arg is not of Event", method));
+                    else if (method.getParameterTypes().length != 1)
+                        throw new IllegalArgumentException(String.format("%s#%s is an invalid listener", method.getDeclaringClass(), method.getName()));
+
+                    @SuppressWarnings("unchecked")
+                    Class<? extends Event> eventType = (Class<? extends Event>) maybeEventType;
                     EventMethod eventMethod = method.getAnnotation(EventMethod.class);
 
                     String customId = null;