Great question—this is a common pitfall when working with LiveData outside of Android's built-in lifecycle components like Activities or Fragments. Let's break down both your approaches, their garbage collection (GC) implications, and their inherent flaws:

Method 1: Turning Your Class into a LifecycleOwner #

By implementing LifecycleOwner with a LifecycleRegistry, you're aligning your class with Android's lifecycle-aware pattern. Here's what you need to watch out for:

Garbage Collection Risk #

This approach can prevent your MyObservingClass instance from being GC'd if you don't properly manage the lifecycle state. When you set lifecycleRegistry.currentState = Lifecycle.State.STARTED, LiveData registers your observer and maintains a strong reference to it. As long as the lifecycle state stays above DESTROYED, LiveData will hold onto that observer—and since the observer holds a reference to your MyObservingClass instance, the entire object can't be garbage collected, even if all other references to it are gone.

Key Flaws #

• Manual lifecycle management burden: You're fully responsible for updating the lifecycle state. If library consumers forget to trigger a transition to DESTROYED (e.g., via a cleanup method you provide), memory leaks are guaranteed.
• Potential confusion for users: The LifecycleOwner interface is closely tied to Android's system components. Using it in a custom class might confuse developers who expect lifecycle states to mirror Activities/Fragments.

Method 2: Using observeForever #

The observeForever method skips lifecycle checks entirely, attaching a permanent observer to the LiveData. Here's the lowdown:

Garbage Collection Risk #

This approach will absolutely prevent GC unless you explicitly remove the observer. observeForever doesn't associate the observer with any lifecycle—LiveData keeps a strong reference to it indefinitely. Even if your MyObservingClass instance is no longer used anywhere else, the observer will keep it alive, leading to a persistent memory leak.

Key Flaws #

• No automatic cleanup: Unlike lifecycle-aware observation, there's no built-in mechanism to stop observing. You must manually call removeObserver() on the LiveData when your class is done processing events.
• Unrestricted event delivery: The observer will receive every LiveData update, even when your class is in a state where it shouldn't handle events (e.g., after it's supposed to be shut down). This can cause unexpected behavior or wasted resources.

Recommendations for Your Library #

Since you're working without system lifecycle components:

• Opt for Method 1 with explicit cleanup: Add a public method like cleanup() or destroy() to MyObservingClass that sets lifecycleRegistry.currentState = Lifecycle.State.DESTROYED. Make sure to document this clearly—users must call this method when they're finished with the instance to avoid leaks. This leverages LiveData's built-in logic to remove observers when the lifecycle is destroyed.
• If using Method 2, enforce observer removal: Store a reference to the observer instance in MyObservingClass, then add a public method (e.g., stopObserving()) that calls Server.dataObject.removeObserver(yourObserver). Again, emphasize this requirement in your library's documentation.

内容的提问来源于stack exchange，提问作者SayantanRC