Auto-increment the version number in an Android App

build.gradle

// Android build.gradle
// How to auto-increment the version.
// There are many ways to do this - this is only one example. Its downside is that it updates the gradle file (which will ask for a Sync when opened).
// Note that the 10001 (rather than just 1) is ensure there are enough digits to prevent comparison/sorting issues.
//
// By Andrew Kingdom
// MIT license
// (and use at own risk)
//

plugins {
    id 'com.android.library'
}

// HERE>
version='1.0.0.10001'  // *** Set a varible, which gets updated...
def versionbuild=10001  // *** set a variable, which gets updated...

android {
    namespace 'com.example.apps.myappname'
    compileSdk 32

    defaultConfig {
        minSdk 24
        targetSdk 32

// HERE>
        versionName version  // *** version variable
        versionCode versionbuild  // *** versionbuild variable

        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
        consumerProguardFiles "consumer-rules.pro"
    }

  
    buildTypes {
        debug {
            minifyEnabled false
//            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
// HERE>
            buildConfigField "String", 'LIB_VERSION', '"' + version + '"'  // *** version variable
        }
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
// HERE>
            buildConfigField "String", 'LIB_VERSION', '"' + version + '"'  // *** version variable
        }
    }
    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }


}

// (*** no changes here)
dependencies {

    implementation 'androidx.appcompat:appcompat:1.5.1'
    implementation 'com.google.android.material:material:1.6.1'
    testImplementation 'junit:junit:4.13.2'
    androidTestImplementation 'androidx.test.ext:junit:1.1.3'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.4.0'
}

// HERE>
// *** Include this code that updates the variable...
task autoincrementversion() {
    // dependson can be assemble, assembledebug or assembleRelease

    // Auto-increment version...
    def v = version
    println v
    String minor=v.substring(v.lastIndexOf('.')+1) //get last digit
    int m=minor.toInteger()+1                      //increment
    println m
    String major=v.substring(0,v.lastIndexOf("."));       //get the beginning
    println major
    String s=buildFile.getText().replaceFirst("version='$version'","version='"+major+ "." +m+"'").replaceFirst("def versionbuild=$versionbuild","def versionbuild="+m);
    println s
    buildFile.setText(s) //replace the build file's text
    // ... Auto-increment version end

}