gradle - How to have two build flavors inherit from a root flavor in Android Studio?

Question

I used to have the following project flavors:

1. Apple
2. Orange

Originally the only difference was the applicationId/packageName. Now there is a single java file that is different. A custom ArrayAdapter to be exact. The solution was to create src/Apple and src/Orange and both inherit from src/main. I removed the java file from src/main and put a copy into src/Apple and src/Orange and modified it appropriately. All was good in the world.

Fast forward a few weeks, now there are about 10 java files that differ between Apple and Orange. Again... no big deal. Easy to handle. Separate java files in src/Apple and src/Orange.

Fast forward to today. I need to modify things up a bit, because I want to have a free and premium version of each. The free and premium versions only differ by a URL. I was going to simply create the new types called:

1. AppleFree
2. ApplePremium
3. OrangeFree
4. OrangePremium

I have a dilema though. Since now src/Apple and src/Orange have 10 different files that have been changed... if I change any java file in AppleFree I have to make sure I do the same in ApplePremium. I'm kind of at a crossroads and hope my question makes sense at this point. I have come up with three possible solutions, but I'm not sure how I would implement them/what would be the correct approach/the solution is not what I want.

Solution 1:

Use an if statement if (BuildConfig.FLAVOR==appleFree) {//use free Url} else {// use premium url}

Issue: Both Urls are technically compiled into the apk. I do not want this.

Solution 2:

Have src/AppleFree and src/ApplePremium inherit from an src/Apple parent directory somehow.

Issue: Not sure how I would do this.

Solution 3:

Add the free and premium url right in build.gradle like so?

    productFlavors {
            appleFree {
                applicationId "com.example.apple.free"
                versionName "1.0"
                url "http://freeurl.com"
                versionCode 1
            }
            applePremium {
                applicationId "com.example.apple.premium"
                versionName "1.0"
                url "http://premiumurl.com"
                versionCode 1
            }
            orangeFree {
                applicationId "com.example.orange.free"
                versionName "1.0"
                versionCode 1
                url "http://freeurl.com"


            }
            orangePremium {
                applicationId "com.example.orange.premium"
                url "http://premiumurl.com"
                versionName "1.0"
                versionCode 1

            }
        } 

Issue: Not sure how to make that work.

Any tips are helpful.

EDIT:

Final Solution?

flavorGroups 'fruit', 'paid'

productFlavors {
    apple {
        flavorGroup 'fruit'
    }
    orange {
        flavorGroup 'fruit'
    }
    free {
        flavorGroup 'paid'
    }
    premium {
        flavorGroup 'paid'
    }
    appleFree {
        applicationId "com.example.apple.free"
        versionName "1.0"
        buildConfigField 'String', 'BASE_URL', 'http://freeurl.com'
        versionCode 1
    }
    applePremium {
        applicationId "com.example.apple.premium"
        versionName "1.0"
        buildConfigField 'String', 'BASE_URL', 'http://premiumurl.com'
        versionCode 1
    }
    orangeFree {
        applicationId "com.example.orange.free"
        versionName "1.0"
        versionCode 1
        buildConfigField 'String', 'BASE_URL', 'http://freeurl.com'
    }
    orangePremium {
        applicationId "com.example.orange.premium"
        buildConfigField 'String', 'BASE_URL', 'http://premiumurl.com' 
        versionName "1.0"
        versionCode 1
    }
    }

Answer 1

There are many possible solutions to your problem. The most native-Gradle solution would be to use Flavor Dimensions, as documented in http://tools.android.com/tech-docs/new-build-system/user-guide#TOC-Multi-flavor-variants

This is also similar to what you were thinking about with Solution 2.

It would work something like this:

flavorDimensions 'fruit', 'paid'

productFlavors {
    apple {
        dimension 'fruit'
    }
    orange {
        dimension 'fruit'
    }
    free {
        dimension 'paid'
    }
    premium {
        dimension 'paid'
    }
}

This will give you build variants (and source folders) where it does the combination of all possibilities out of each flavor dimension, maintaining the same order as how the groups are specified in your flavorDimensions statement (i.e. it's appleFree, not freeApple), thus:

* appleFree
* applePremium
* orangeFree
* orangePremium

in your src/ folder, you can have these possibilities:

* src/main
* src/apple
* src/orange
* src/free
* src/premium
* src/appleFree
* src/applePremium
* src/orangeFree
* src/orangePremium

---

Solution 3

You can use the buildConfigField to specify constants that go in the BuildConfig class on a flavor-by-flavor basis:

productFlavors {
    appleFree {
        buildConfigField 'String', 'MY_URL', 'value1'
    }
    applePremium {
        buildConfigField 'String', 'MY_URL', 'value2'
    }
    orangeFree {
        buildConfigField 'String', 'MY_URL', 'value3'
    }
    orangePremium {
        buildConfigField 'String', 'MY_URL', 'value4'
    }

---

Solution 1

I was trying to work up something along the lines of Solution 1, but it won't work well for your exact use case. If you have an if condition in Java that tests against a boolean that's declared static final then the compiler can determine statically whether the code is reachable or not, and it will strip it if it's not. Thus:

static final boolean DEBUG = false;

...

if (DEBUG) {
    // do something
}

The code in // do something won't get compiled at all. This is an intentional and documented behavior on the part of the Java compiler, and allows you to write expensive debug code that won't get compiled into your release binary. BuildConfig.DEBUG is declared as static final for this exact reason.

There's a BuildConfig.FLAVOR, but it's defined as String, and you don't get the same benefit:

static final String FLAVOR = "orange";

...

if (FLAVOR.equals("apple")) {
    // do something
}

The compiler isn't smart enough to do static analysis, see that // do something is unreachable, and not compile it. Note that it will work fine at runtime, but that dead code will be included in your binary.

If it suits you, though, you could steal the buildConfigField approach from above and define an extra boolean variable in some variants that could allow code to be conditionally compiled in. This is more complex than defining the string directly as in Solution 3, but if you find yourself wanting to differentiate behavior without going through the trouble of making flavor-specific subclasses, you could go this route.