Add auto incremented versionCode using a properties file

build.gradle

/**
     * Adds auto incremented versionCode number
     * Found on stackoverflow
     * see https://stackoverflow.com/a/25166200/1469260
     */
    def Properties versionProps = new Properties()
    def versionPropsFile = file('version.properties')
    if (versionPropsFile.exists())
        versionProps.load(new FileInputStream(versionPropsFile))
    def code = (versionProps['VERSION_CODE'] ?: "0").toInteger() + 1
    versionProps['VERSION_CODE'] = code.toString()
    versionProps.store(versionPropsFile.newWriter(), null)

    defaultConfig {
        applicationId "com.example.android.miwok"
        minSdkVersion 15
        //noinspection OldTargetApi
        targetSdkVersion 25
        versionCode code
        versionName "1.2." + code
    }