I'm using API 17 and I'm looking for a way to set the whole app to rtl instead of using
<android:layoutDirection="rtl"> in every single activity layout.
Please check this text extract from android developers weblog:
To take advantage of RTL layout mirroring, simply make the following changes to your app:
1- Declare in your app manifest that your app supports RTL mirroring. Specifically, add android:supportsRtl="true" to the element in your manifest file.
2- Change all of your app's "left/right" layout properties to new "start/end" equivalents. If you are targeting your app to Android 4.2 (the app's targetSdkVersion or minSdkVersion is 17 or higher), then you should use start and end instead of left and right. For example, android:paddingLeft should become android:paddingStart.
If you want your app to work with versions earlier than Android 4.2 (the app's targetSdkVersion or minSdkVersion is 16 or less), then you should add start and end in addition to left and right. For example, youd use both android:paddingLeft and android:paddingStart.
the full text can be found here: