Answer by Alex Cohn for How to remove all debug logging calls before building the release version of an Android app?

If you can run a global replace (once), and after that preserve some coding convention, you can follow the pattern often used in Android framework.

Instead of writing

Log.d(TAG, string1 + string2 + arg3.toString());

have it as

if (BuildConfig.DEBUG) Log.d(TAG, string1 + String.format("%.2f", arg2) + arg3.toString());

Now proguard can remove the StringBuilder and all strings and methods it uses on the way, from optimized release DEX. Use proguard-android-optimize.txt and you don't need to worry about android.util.Log in your proguard-rules.pro:

android {
  …
  buildTypes {
    release {
      minifyEnabled true
      proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
    }
  }
}

With Android Studio gradle plugin, BuildConfig.DEBUG is quite reliable, so you don't need extra constants to control the stripping.