Skip to content

App Context

Always have your application Context at hand with appCtx.

Supported platforms: Android.

This split provides two read-only properties:

  • appCtx that returns your Application Context
  • directBootCtx for your direct boot aware components where storage is involved, if any.

It also brings these 2 extensions functions on Context for advanced usages: - injectAsAppCtx() - canLeakMemory()

You can use appCtx and directBootCtx anywhere in your app (without risking leaking a short-lived context such as an Activity or a Service). This makes writing code that needs a Context for non Activity specific purposes more convenient.

Important: use the right context!

You may not want to use the Application Context in some cases.

Context for storage

If you need a Context to access storage from a library (for SharedPreferences, a database or other files), you should allow passing a specific Context that could default as appCtx, so it is possible for target apps to use a special Context like directBootCtx.

Configuration dependent or themed Context

Devices on which your app/library runs may (will) change configuration during the app’s process lifecycle, such as screen density, language or orientation.

Please, do not use appCtx or directBootCtx if you rely on a “scoped” Context to access themed resources from an Activity, or configuration dependent values/resources.

Note that in some cases, configuration dependent context usage may be ok if your component handles onConfigurationChanged() properly. More generally, if you wonder if using Application Context is ok, test your app against configuration changes that may affect it and check it reacts correctly.

How it works

This library takes advantage of Content Providers to automatically initialize appCtx for you before even your Application‘s onCreate() is called! This library also takes advantage of manifest placeholders (with the default ${applicationId}) and gradle manifest merging to avoid two apps using this library clashing with same authority Content Providers.

This is the same trick used by Firebase to auto-initialize the library. You can read more on this here.

Advanced use cases

Multi-process apps and libraries

While most apps run on single-process, on the default one, some need to run some components in different processes. If your app needs to access appCtx or directBootCtx directly, or indirectly in a component that has it’s android:process tag in AndroidManifest.xml set to :the_name_of_your_private_process or the_fully_qualified_name_of_your_shared_process, you have 3 solutions: 1. Do nothing and let appCtx init itself with reflection on first access 2. Call injectAsAppCtx() in the onCreate() method of your custom Application subclass. 3. Subclass AppCtxInitProvider and declare it correctly in your AndroidManifest.xml for each non default process. This option may be the best one if you’re making a library that has its own process as no further configuration will be required on the app side. See instructions below:

How to declare an AppCtxInitProvider correctly (for multi-process usage)

  1. Subclass AppCtxInitProvider
  2. Register your subclass as a provider in your AndroidManifest.xml file.
  3. Specify it’s android:process attribute to the name of your app’s non default process. (beware of typos)
  4. Set android:exported to false.
  5. Set android:authorities to something other than ${applicationId}.appctxinitprovider. The suggested naming convention is ${applicationId}.appctxinitprovider.the_name_of_your_process so the content provider authority doesn’t clash with another one from your app, or from a third-party app.
  6. If your component is Direct Boot aware, add android:directBootAware="true".
  7. If you use appCtx or directBootCtx in another Content Provider, make sure to specify android:initOrder to a higher value than the one of the other Content Provider which use the ctx properties.

The result should look like this:

<provider
    android:name=".SecondProcessInitProvider"
    android:authorities="${applicationId}.appctxinitprovider.second_process"
    android:exported="false"
    android:initOrder="900"
    android:process=":second_process"/>

import AppCtxInitProvider

class SecondProcessInitProvider : AppCtxInitProvider()

Download

implementation("com.louiscad.splitties:splitties-appctx:3.0.0-beta01")