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If I want to pass data between activities in the same application, a) I can use an Intent or b) use a database (passing the id in the Intent instead of the full data.
But I could also use c) a class with static data structures that both activities can access in a store/fetch fashion.
What are the cons of using (c) if I don't care about persistence of the data on app restart?

Jim
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    The c option is the example of Repository pattern, and the repository is singleton. – Manuel Mato Mar 18 '20 at 08:18
  • @ManuelMato: I thought the repository pattern means access to a DB (or remote server DB) – Jim Mar 18 '20 at 08:18
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    I use the repository to create a flow data between more datasource and use too a cache datasource, but if you haven´t more datasource, maybe you could do all in the repository class – Manuel Mato Mar 18 '20 at 08:21
  • @ManuelMato: Your suggestion helps on how to properly design the code. But the question is about potential issues we face by storing the data in static structures during the activities lifecycle – Jim Mar 18 '20 at 08:40
  • ah ooki, I had not understood the statement, sorry xD – Manuel Mato Mar 18 '20 at 08:44

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The big cons is that the Android OS can kill your process at any time. When the process will be re-created, Android will re-create all of your activities restoring their state.

Since Android doesn't know about how your static data should be handled, you will lose it and Activity B will be in an inconsistent state.

I'll make an example to be clearer:

  1. Activity A is launched
  2. A button on Activity A is clicked
  3. Static data structures are being populated before launching Activity B
  4. Activity B is launched and can access the static data
  5. Android OS kills automatically your process
  6. Activity A and Activity B are restored
  7. The static data structures are not populated since they would have been populated when the button on Activity A is clicked
  8. Activity B is in an inconsistent state
Giorgio Antonioli
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