Semantic Versioning for android application

versioning.gradle

/**
 * Will generate versionCode from versionName that follows Semantic Versioning 
 */
ext {
    /**
     * Application version is located version variable.
     * And should follow next policy:
     * X1.X2.X3-type-flavor, where X - any digits and type is optional alphabetical suffix.
     * X1 - major version
     * X2 - minor version
     * X3 - patch
     * There are next supported type:
     *  dev - code 0
     *  alpha - code 1
     *  beta - code 2
     *  no suffix - code 9 - means final production build from market.
     * flavors currently disabled, value (0)
     */
    buildVersionCode = { String versionName ->
        /**
         * Here is representation of Version code generation from version name.
         *
         *  *--------- major version
         *  |  *------ minor version
         *  |  |  *--- patch version
         *  |  |  |*-- buildType (dev/alpha/beta/rc/release)
         *  |  |  ||*- flavor - disabled.
         *  |  |  |||
         *  X00X00XXX
         * so
         *  1.13.20-alpha-v19 = 10130201
         * see details below:
         *  *--------- 1 is major version
         *  |  *------ 13 is minor version
         *  |  |  *--- 20 is patch version
         *  |  |  |*-- type 1 is alpha.
         *  |  |  ||*- flavor 0 (disabled)
         *  |  |  |||
         *  101302010
         */

        def (mainPart, typeName) = versionName.toLowerCase().tokenize('-')

        if (typeName == null) {
            type = "9"
        } else if (typeName.equals("dev")) {
            type = "0"
        } else if (typeName.equals("alpha")) {
            type = "1"
        } else if (typeName.equals("beta")) {
            type = "2"
        } else {
            println("Unknown build type = " + typeName + ". Please look into app/versioning.gradle.")
            throw new RuntimeException("Unknown type = " + typeName)
        }

        /**
         * At the project start time, there was flavor support.
         * Now we should reserve last digit, because removing it will reduce version code 10 times.
         * And next version will have versionCode less than previous.
         */
        flavor = "0" // disabled

        int flavorDigit = 1
        int typeDigit = flavorDigit * 10
        int patchDigit = typeDigit * 10
        int minorDigit = patchDigit * 1000
        int majorDigit = minorDigit * 1000

        def (major, minor, patch) = mainPart.tokenize('.')
        (major, minor, patch, type, flavor) = [major, minor, patch, type, flavor].collect {
            it.toInteger()
        }
        (major * majorDigit) + (minor * minorDigit) + (patch * patchDigit) + (type * typeDigit) + (flavor * flavorDigit);
    }
}

this is great as you covered all the use cases even the edge ones, good work

For those who don't know, one of the examples of flavor are "free" and "paid" version of your app

https://www.journaldev.com/21533/android-build-types-product-flavors

If you just making a free apps, just disable it like this script mentioned. If not, just make a different suffix number for each of flavor