CODEWITHSUNDEEP
androidarchitecture
user860302
user860302

Reputation: 127

Help with the architecture of my Android app

I would like to write an app to follow the price of lists of stocks. There would be three activities containing lists of stocks :

I would like to persist the list of stocks in myStocksActivity, to be able to remove or add stocks from that list and to add the stocks displayed in searchedStocksActivity or winnersLoosersStocksActivity to myStocksActivity.

Another challenge : the price of the stocks should be updated every X minutes depending on the settings of app. The prices should only be updated when the app is running and should only update the prices of the list I'm currently looking at.

For the moment, my architecture isn't great : almost all the logic is contained in myStocksActivity and I know it's not a good thing.

I was thinking about moving the update of the stock list to a service, but I don't want this service to run when the application is not running.

What do you think ? Is my problem clear ? Thank you !

Upvotes: 1

Views: 257

Answers (3)

JustDanyul
JustDanyul

Reputation: 14044

If I was you I would try and design(and build) a domain model first. This should end up being a set of classes which allows you to do everything you want with your stocks, independently of the a UI. You should also build in data persistence directly into these classes (i suggest using SQLite for this bit).

Then once you have a working model, build the UI on top of that. The MVP design pattern works pretty well with android.

Implement your activities as Views, these should both present data, and captures UI events and delegate these events to to Presenter instances, which then communicate/manipulate the model, and updates the Views accordingly. For example,

MyStocksView could present the user with a list of stocks, and the latest movements of stock price (or whatever). The MyStocksView contains the actual widgets that make up the user interface, and also acts as event listener and handler for various UI events (like when the user click a button). It should also contain a instance of a MyStocksPresenter class.

Once the user clicks the button, lets say, "remove stock", the event handler of MyStocksView then fires a method in the presenter instance for example, presenter.removeStock(id) , this method then updates the model (removes it from the in-memory data structures and database) and finally, if everything was successful, updates the View. It basically works as a middle man between the presentation layer, and the data-model.

In regards to the automatic updates every X minutes, I would handle this with a AsyncTask, there's not really much point in using a service if you only want this to happen while you app is running.

Upvotes: 1

Izkata
Izkata

Reputation: 9323

  1. Create a class for a stock, and store the update logic in there
  2. I would put the handler - what holds instances of the stock-class and loops over a set to tell them to update - either in its own class purely with static methods and variables, or also in the stock class with static methods/etc.
  3. The service then contains timing information, and calls the static update() method
  4. The activity that displays stocks starts/stops the service with onCreate/onDestroy or onUpdate/onPause (I think it's update; the on that happens each time the Activity is brought to the forefront)
  5. Same activity tells the handler class which ones to load, and uses its list for the display.

One other thing: I'd suggest against using a service. Use an AsyncTask. Services actually do run on the UI thread, so if there's a long-running loop during the update, the UI will freeze. AsyncTask starts a thread and will not block the UI.

Upvotes: 0

dasfima
dasfima

Reputation: 5301

Whenever you main activity gets paused (or destroyed), call StopService(blabla);. That way you can keep it as a service, and it won't run in the background.

Upvotes: 0

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