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How to save the user's selection for every time they run the app on Android?

开发者 https://www.devze.com 2023-03-27 14:32 出处:网络
The first time the app is run, I want to have a checkbox list appear where the user selects the list items that they are interested in, and run the program based on that. Every subsequent time the app

The first time the app is run, I want to have a checkbox list appear where the user selects the list items that they are interested in, and run the program based on that. Every subsequent time the app is run, I want those selected settings to be remembered, or changed with an options menu, in which case the new settings will be remembered. But all I know how to do is make an app go from the beginning every time it is run...

Similarly, my app reads sequentially through all the data in a large, read-only, unchangable database. As of right now, it creates and opens and fetches all the data every time, which takes a few seconds at the start of the program to open up and do anyt开发者_如何学Gohing. Is there a way to get around this, or, is it even a good idea to try to get around this?


To remember the users selection, have a look at SharedPreferences. You can store the selected items there.

To the database: That really depends on your app. If you need all that data at the same time in memory, I guess theres no way around loading it at the start. If you only need parts, it would be a good idea to load a part of the data when required. But without exact knowledge of your app/use case, this is hard to tell.

When you have some sort of "lag" when loading the database: Do you probably load the database in the UI-thread (= without creating a seperate thread for loading)? Thats bad practice since it blocks all UI operations. Have a look at AsyncTasks. Thats a handy class that wraps around a thread and lets you do things in the background without blocking all the UI. After it's done with its task (loading in this case) it provides you a onPostExecute() callback where you can update your UI with the loaded data.

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