Gradle automatically generates version number from git and uses it in Java

Thing you want to do

• Generate version number from git tag and commit hash
• Narrow down only the tag indicating the version from the tags
• Use automatically generated version number from Java code

Referenced site

Automatically assign version number with Gradle ~ Collaboration with git-describe grgit-gradle BuildConfig Gradle-plugin for Java and Groovy projects

Implementation

• Get version number with grgit
• v Ignore other tags, with tags starting with [number] as version tags
• BuildConfig automatically generates a class containing the version number and uses it from java code
• It seems that the android plugin includes BuildConfig, but this time I will use the BuildConfig plugin

build.gradle

plugins {
    id 'idea'
    id 'application'
    id 'org.ajoberstar.grgit' version '3.1.1'
    id 'de.fuerstenau.buildconfig' version '1.1.8'
}

group 'com.example'
version = {
    def tags = grgit.tag.list().collect { it.getName() }
    def versionStr
    if (tags.any { it ==~ /v\d.*/ }) {
        versionStr = grgit.describe(longDescr: false, tags: true, match: ["v[0-9]*"])
    } else {
        versionStr = grgit.head().abbreviatedId
    }
    return versionStr + (grgit.status().isClean() ? "" : "+dirty")
}()

repositories {
    mavenCentral()
}

task showVersion {
    doLast {
        println version
    }
}

mainClassName = 'Main'

Main.java

import com.example.BuildConfig;

public class Main {

    public static void main(String... args) {
        System.out.println(BuildConfig.VERSION);
    }
}

Execution example

If there is no tag indicating the version

2f9b747  //Commit hash

If HEAD has a tag indicating the version

v0.1

When committing additionally from the tag indicating the version

v0.0-10-g3636be7

If there are uncommitted changes

v0.0-10-g3636be7+dirty