Generating constants for all flavors (type-safe, unlike using a string)

build.gradle

android {
  ...
  productFlavors.all { flavor ->
    defaultConfig {
      buildConfigField "String", "FLAVOR_" + flavor.name.toUpperCase(), "\"${flavor.name}\""
    }
  }
  ...
}

YourCode.java

if (BuildConfig.FLAVOR.equals(BuildConfig.FLAVOR_YOURFLAVOR)) {
  // do something
}