Android configuration in meta-data or in properties file?

Question

I'm writing a library that is used by developers and I have a configuration items like apiKey, environment and others. I want to developer to set these values, my first thought was using Java Properties file that I load in the Application class, but I've seen Google Play and Google Map SDK ask the developers to add their apiKey in meta-data tag in Android Manifest. What is the recommended way?

Answer 1

The recommended android way to let the user define values for your library from the application module is through meta-tags

it is as easy as using this code on the android-manifest

<meta-data android:name="com.yourproject.apikey" android:value="apikey"/>

and you can get these values from your library like this

try {
    ApplicationInfo applicationInfo = getPackageManager().getApplicationInfo(activity.getPackageName(), PackageManager.GET_META_DATA);
    Bundle bundle = applicationInfo.metaData;
    String apiKey = bundle.getString("com.yourproject.apikey");
} catch (NameNotFoundException e) {
    //Resolve error for not existing meta-tag, inform the developer about adding his api key
}

The main benefits of this approach are

1) That you can let the user define different values per device type e.g. phone, tablet or sdk-version (this may not be applicable for your case but it's a good point for sure)

2) You can add complex data as the value in your meta-tag, and you can use this if you want to add a string-array with all the value that you want to declare.

3) Since meta-tags are basically a bundle it is easier for you to

• Read these values on your library code.

• Have default values if the user has not declared the required meta-tags.

(I believe that parsing properties from assets requires more code without any great advantage)

4) You can also add configuration meta-tags for activities,providers and broadcastreceiver on your AndroidManifest.

5) Also I suppose that it is easier to request for the consumers of your library to add a few meta info on his Android Manifest, than adding a properties file on their assets folder.And i believe that this is the main reason Many known libraries use this approach like google-play-service, google-maps, crash reporting libraries and many libraries that provide user analytic.

Good Luck