gradle-groovy

name	gradle-groovy
description	Expert guidance on writing and maintaining Android Gradle build files in Groovy DSL for a Java project — product flavors, signing configs, build types, and dependency management. Use this when configuring build.gradle for new modules or flavors.

Android Gradle (Groovy DSL)

Instructions

Groovy DSL (build.gradle) is acceptable; Kotlin DSL (build.gradle.kts) is preferred for new modules because of IDE autocomplete and type safety. This skill targets Groovy because many Java projects inherited it from older AGP versions.

1. Root build.gradle

buildscript {
    ext {
        agpVersion     = '8.5.2'
        javaVersion    = JavaVersion.VERSION_17
        minSdkVersion  = 21
        targetSdkVersion = 35
        compileSdkVersion = 35
    }
}

plugins {
    id 'com.android.application' version "$agpVersion" apply false
    id 'com.android.library'     version "$agpVersion" apply false
    id 'com.google.dagger.hilt.android' version '2.52'  apply false
    id 'androidx.navigation.safeargs'    version '2.8.0' apply false
}

tasks.register('clean', Delete) {
    delete rootProject.layout.buildDirectory
}

2. Module build.gradle

plugins {
    id 'com.android.application'
    id 'com.google.dagger.hilt.android'
    id 'androidx.navigation.safeargs'
}

android {
    namespace 'com.example.app'
    compileSdk rootProject.compileSdkVersion

    defaultConfig {
        applicationId "com.example.app"
        minSdk rootProject.minSdkVersion
        targetSdk rootProject.targetSdkVersion
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "com.example.app.HiltTestRunner"
        resourceConfigurations += ['en', 'es', 'fr']
    }

    compileOptions {
        sourceCompatibility rootProject.javaVersion
        targetCompatibility rootProject.javaVersion
    }

    java {
        toolchain {
            languageVersion = JavaLanguageVersion.of(17)
        }
    }

    buildFeatures {
        viewBinding true
        buildConfig true
    }
}

namespace is required on AGP 8. Do not duplicate it in AndroidManifest.xml.

3. Build Types

android {
    buildTypes {
        debug {
            applicationIdSuffix '.debug'
            versionNameSuffix '-DEBUG'
            buildConfigField 'String', 'API_BASE_URL', '"https://api-staging.example.com/"'
        }
        release {
            minifyEnabled true
            shrinkResources true
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'),
                          'proguard-rules.pro'
            signingConfig signingConfigs.release
            buildConfigField 'String', 'API_BASE_URL', '"https://api.example.com/"'
        }
    }
}

4. Product Flavors

android {
    flavorDimensions 'tier', 'env'

    productFlavors {
        free {
            dimension 'tier'
            applicationIdSuffix '.free'
            buildConfigField 'boolean', 'IS_PREMIUM', 'false'
        }
        premium {
            dimension 'tier'
            applicationIdSuffix '.premium'
            buildConfigField 'boolean', 'IS_PREMIUM', 'true'
        }
        staging {
            dimension 'env'
            buildConfigField 'String', 'ANALYTICS_KEY', '"stg-xxx"'
        }
        production {
            dimension 'env'
            buildConfigField 'String', 'ANALYTICS_KEY', '"prod-xxx"'
        }
    }
}

Variants: freeStagingDebug, premiumProductionRelease, etc.

Per-flavor resources:

src/premium/res/drawable/ic_app_logo.xml
src/staging/res/values/strings.xml

5. Signing

Never commit keystores or passwords. Read from Gradle properties / env vars.

android {
    signingConfigs {
        release {
            storeFile     file(System.getenv('KEYSTORE_PATH') ?: 'release.keystore')
            storePassword System.getenv('KEYSTORE_PASSWORD')
            keyAlias      System.getenv('KEY_ALIAS')
            keyPassword   System.getenv('KEY_PASSWORD')
        }
    }
}

In CI, inject via secrets. Local developers set values in ~/.gradle/gradle.properties.

6. Dependency Declarations

Prefer libs.versions.toml version catalog even with Groovy:

# gradle/libs.versions.toml
[versions]
retrofit = "2.11.0"
okhttp   = "4.12.0"
moshi    = "1.15.1"
hilt     = "2.52"

[libraries]
retrofit     = { module = "com.squareup.retrofit2:retrofit", version.ref = "retrofit" }
retrofit-moshi = { module = "com.squareup.retrofit2:converter-moshi", version.ref = "retrofit" }
okhttp       = { module = "com.squareup.okhttp3:okhttp", version.ref = "okhttp" }
moshi        = { module = "com.squareup.moshi:moshi", version.ref = "moshi" }
hilt-android = { module = "com.google.dagger:hilt-android", version.ref = "hilt" }
hilt-compiler = { module = "com.google.dagger:hilt-compiler", version.ref = "hilt" }

dependencies {
    implementation libs.retrofit
    implementation libs.retrofit.moshi
    implementation libs.okhttp
    implementation libs.moshi
    implementation libs.hilt.android
    annotationProcessor libs.hilt.compiler
}

7. buildSrc or Convention Plugins

Extract repeated module configuration into buildSrc/src/main/groovy/android-app.gradle so each module is a one-liner:

// app/build.gradle
plugins {
    id 'android-app'
}

8. Common Pitfalls

• Do not upgrade AGP without reading the release notes; compatibility with Gradle, JDK, and Kotlin is strict.
• packagingOptions { resources.excludes += ['META-INF/*.md'] } — keep this explicit, not copy-pasted.
• Test dependencies must not leak into implementation; use testImplementation / androidTestImplementation.
• When multiple flavors share a large block, use productFlavors.all { ... }.

Checklist

• AGP, Gradle, JDK versions are aligned with a known-good matrix.
• namespace is set in every module's build.gradle.
• Java source/target compatibility and toolchain are both set to 17.
• Keystore and passwords are not in source control.
• A version catalog (libs.versions.toml) is the single source of truth for versions.
• Flavor-specific code lives in src/<flavor>/ folders, not behind if (BuildConfig.FLAVOR) branches.
• Release build runs minifyEnabled true and shrinkResources true.