build.gradle

// Top-level build file where you can add configuration options common to all sub-projects/modules.
buildscript {
    repositories {
        jcenter()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:2.2.1'

        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}

allprojects {
    repositories {
        jcenter()
    }

    ext.versionMajor = 1
    ext.versionMinor = 0
    ext.versionPatch = 1
    ext.versionClassifier = "SNAPSHOT"

    project.ext {
        versionCode = ext.versionMajor * 10000 + ext.versionMinor * 100 + ext.versionPatch
        versionName = getVersionName()
    }
}

task clean(type: Delete) {
    delete rootProject.buildDir
}

public String getVersionName() {
    String versionName = "${ext.versionMajor}.${ext.versionMinor}.${ext.versionPatch}"
    if (ext.versionClassifier != null && !ext.versionClassifier.isEmpty()) {
        versionName = versionName + "-" + ext.versionClassifier
    }
    return versionName;
}