Android build types and build variants

During development, we might need to configure the code to use different api endpoint, or other environment variables for dev, staging and prod builds. This can be done by defining different build types in the Android app build gradle file.

Here is the an example configuration for defining different build types, debug, dev, staging and release.

android {
    signingConfigs {
        config {
            keyAlias 'build_variant'
            keyPassword 'android'
            // update this path to your keystore file path
            storeFile file('/path/to/the/android/project/folder/app/debug.keystore')
            storePassword 'android'
        }
    }
    buildTypes {
        debug {
            applicationIdSuffix = ".debug"
            versionNameSuffix "-debug"
        }
        dev {
            initWith debug
            applicationIdSuffix = ".dev"
            versionNameSuffix "-dev"
            debuggable true
        }
        staging {
            initWith debug
            applicationIdSuffix = ".staging"
            versionNameSuffix "-staging"
        }
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
            signingConfig signingConfigs.config
        }
    }
}

Let’s create a strings.xml in each of the following path with different values assigned to the string variable build_type and api_domain.

app/src/debug/res/values/strings.xml

    Build Variants
    Debug
    https://debug.example.com

app/src/dev/res/values/strings.xml

    Build Variants
    Dev
    https://dev.example.com

app/src/staging/res/values/strings.xml

    Build Variants
    Staging
    https://staging.example.com

app/src/release/res/values/strings.xml

    Build Variants
    Release
    https://www.example.com

app/src/main/res/values/strings.xml

    Build Variants
    Build Type

In the code, it is the same as to how to pulling in the string resources, here is the example of setting a TextView with a string from the strings.xml, it will get the appropriate strings.xml according to the selected build variant.

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        // for a staging build, it will get the api_domain defined in the in the staging folder. and for other builds, it will get the api_domain defined in other folder. 
        tv_domain.text = getString(R.string.api_domain)
    }
}

The build variant can be select by Click the build variant on the left bottom, and select the build variant. For example, if the staging build variant is selected, the apk will use the strings.xml from app/src/staging/res/values/strings.xml. This applies to other resources as well, such as drawables, colors, integers, etc.

Complete example in Github