BLoC PatternEasy20 XP3 min read
What is the difference between Bloc and Cubit?
TL;DR: Cubit is a simplified Bloc that emits states directly via methods, with no Events. Bloc requires an explicit Event class for every state transition, which adds traceability and testability for complex flows.
Full Answer
| Aspect | Cubit | Bloc |
|---|---|---|
| State trigger | Method call (increment()) | Event dispatch (add(IncrementEvent())) |
| Boilerplate | Low — no event classes | Higher — event + handler per action |
| Traceability | Less — methods are implicit | High — every transition is an event |
| Testing | Simple method calls | bloc_test with events |
| Use case | Simple local UI state | Complex domain logic, audit trail |
🎯
Start with Cubit. Upgrade to Bloc when you need to react to external events (WebSocket messages, deep links) or need full transition history for debugging.
Code Examples
dartCubit vs Bloc for a counter
Output
// Both emit new int states // Bloc stores transition history: IncrementEvent -> 1
Common Mistakes
- ✗Using Bloc for simple local toggle state — Cubit is cleaner
- ✗Emitting the same state twice with Cubit — Bloc by default ignores duplicate states (use transformer to allow)
Interview Tip
💡
Show you understand the trade-off: Cubit is less code; Bloc is more debuggable. The BlocObserver in Bloc lets you log every single state transition globally.
#bloc#cubit#event#state