Here is the answer to the Android interview question "When to use AIDL vs Messenger Queue?":
AIDL is used when you need application-level communication to share data and control between processes. For example, an app requires a list of all contacts from the Contacts app and also wants to display the call duration and be able to disconnect it from that app[1][2][3].
In the case of Messenger Queue, you mainly work on multiple threads and processes to manage the queue containing messages so that there is no interference from external services[1][2][3].
Messenger is needed if you want to bind a remote service (e.g. running in another process)[1].
