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Description
Flashcards by Alex Neves, updated more than 1 year ago
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Created by Alex Neves
over 8 years ago
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| Question | Answer |
| What is a Service? | A component with no UI |
| What are they used for? | To perform long running tasks |
| What is their lifetime? | They remain for as long as they are needed |
| What process do they run in? | The same process as the instantiating app |
| Name 4 example usages of a Service | MP3 playback, downloading a file, sending an email and polling for emails |
| Name the 2 types of Services | Bound and Unbound |
| What is an Unbound Service? | A service which runs indefinitely, controlled via calls to startService() and stopService() |
| What is a Bound Service? | A Service which runs for as long as any activities are bound. When all clients unbind, the service is stopped. |
| How do you communicate with a bound service? | Via an IBinder interface instance |
| Name 2 examples of Unbound Services | Intent service and generic started service |
| Describe an Intent Service | A service which queues intents. Handles intents one at a time via onHandleIntent(). Stops when queue has been processed. |
| Give an example of an Intent Service | Sending an email |
| Describe a Generic Started Service | A service which runs persistently. It receives messages requesting work to be done. |
| Give an example of a Generic Started Service | Polling for emails |
| What is a Foreground Service? | One which runs in the foreground, helping prevent termination. It provides a notification to users know it is running. |
| How does a Local Bound Service work? | The Service extends the Binder class. After binding, an async callback is called providing the IBinder instance to the service. |
| What is a Remote Bound Service? | One which can communicate across process boundaries. Likely to be used by multiple processes at once |
| How can we define a Remote Service? | By using AIDL |
| What does AIDL stand for? | Android Interface Definition Language |
| What is AIDL? | The method for communicating across process boundaries. It is similar to Java interface syntax. |
| What types does AIDL support? Name some examples | Primitives e.g. StringList and Map. Also support other AIDL interfaces and paracelable objects |
| What is a Parcelable object? | One which is supported by the Android Kernel Drivier |
| What types are Parcelable? | Primitives e.g. ints, strings, chars, bytes |
| What is the benefit of Parcelable vs Java.IO.Serializable? | Supported by the kernel meaning it is fast. Java.IO.Serializable works via reflection and is therefore slow. |
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