Difference between build.gradle.kts and libs.versions.toml

What's the difference between build.gradle.kts and libs.versions.toml? When should each be used?

build.gradle.kts (:app)

plugins {
    alias(libs.plugins.android.application)
    alias(libs.plugins.jetbrains.kotlin.android)
}

android {
    namespace = "com.companyname.myapplication"
    compileSdk = 34

    defaultConfig {
        applicationId = "com.companyname.myapplication"
        minSdk = 33
        targetSdk = 34
        versionCode = 1
        versionName = "1.0"

        testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
        vectorDrawables {
            useSupportLibrary = true
        }
    }

    buildTypes {
        release {
            isMinifyEnabled = false
            proguardFiles(
                getDefaultProguardFile("proguard-android-optimize.txt"),
                "proguard-rules.pro"
            )
        }
    }
    compileOptions {
        sourceCompatibility = JavaVersion.VERSION_1_8
        targetCompatibility = JavaVersion.VERSION_1_8
    }
    kotlinOptions {
        jvmTarget = "1.8"
    }
    buildFeatures {
        compose = true
    }
    composeOptions {
        kotlinCompilerExtensionVersion = "1.5.1"
    }
    packaging {
        resources {
            excludes += "/META-INF/{AL2.0,LGPL2.1}"
        }
    }
}

dependencies {
    implementation(libs.androidx.core.ktx)
    implementation(libs.androidx.lifecycle.runtime.ktx)
    implementation(libs.androidx.activity.compose)
    implementation(platform(libs.androidx.compose.bom))
    implementation(libs.androidx.ui)
    implementation(libs.androidx.ui.graphics)
    implementation(libs.androidx.ui.tooling.preview)
    implementation(libs.androidx.material3)
    testImplementation(libs.junit)
    androidTestImplementation(libs.androidx.junit)
    androidTestImplementation(libs.androidx.espresso.core)
    androidTestImplementation(platform(libs.androidx.compose.bom))
    androidTestImplementation(libs.androidx.ui.test.junit4)
    debugImplementation(libs.androidx.ui.tooling)
    debugImplementation(libs.androidx.ui.test.manifest)
    implementation(libs.androidx.material3.adaptive.navigation.suite)
}

libs.versions.toml

[versions]
adaptive = "1.1.0-alpha05"
agp = "8.5.0"
kotlin = "1.9.0"
coreKtx = "1.13.1"
junit = "4.13.2"
junitVersion = "1.2.1"
espressoCore = "3.6.1"
lifecycleRuntimeKtx = "2.8.6"
activityCompose = "1.9.2"
composeBom = "2024.04.01"

[libraries]
androidx-adaptive = { module = "androidx.compose.material3.adaptive:adaptive", version.ref = "adaptive" }
androidx-core-ktx = { group = "androidx.core", name = "core-ktx", version.ref = "coreKtx" }
androidx-material3-adaptive-navigation-suite = { module = "androidx.compose.material3:material3-adaptive-navigation-suite" }
junit = { group = "junit", name = "junit", version.ref = "junit" }
androidx-junit = { group = "androidx.test.ext", name = "junit", version.ref = "junitVersion" }
androidx-espresso-core = { group = "androidx.test.espresso", name = "espresso-core", version.ref = "espressoCore" }
androidx-lifecycle-runtime-ktx = { group = "androidx.lifecycle", name = "lifecycle-runtime-ktx", version.ref = "lifecycleRuntimeKtx" }
androidx-activity-compose = { group = "androidx.activity", name = "activity-compose", version.ref = "activityCompose" }
androidx-compose-bom = { group = "androidx.compose", name = "compose-bom", version.ref = "composeBom" }
androidx-ui = { group = "androidx.compose.ui", name = "ui" }
androidx-ui-graphics = { group = "androidx.compose.ui", name = "ui-graphics" }
androidx-ui-tooling = { group = "androidx.compose.ui", name = "ui-tooling" }
androidx-ui-tooling-preview = { group = "androidx.compose.ui", name = "ui-tooling-preview" }
androidx-ui-test-manifest = { group = "androidx.compose.ui", name = "ui-test-manifest" }
androidx-ui-test-junit4 = { group = "androidx.compose.ui", name = "ui-test-junit4" }
androidx-material3 = { group = "androidx.compose.material3", name = "material3" }

[plugins]
android-application = { id = "com.android.application", version.ref = "agp" }
jetbrains-kotlin-android = { id = "org.jetbrains.kotlin.android", version.ref = "kotlin" }

build.gradle.kts and libs.versions.toml do different things but work together

build.gradle.kts:

This is the file where you tell your app how to build. You set things like the Android version, the libraries you’re using, and the tools (plugins) you need.

libs.versions.toml:

This is a file where you keep track of the versions of your libraries and tools. Instead of writing the version numbers in build.gradle.kts, you put them all in libs.versions.toml. It makes updating versions easier because they’re all in one place.

Example:

In build.gradle.kts you might say

implementation(libs.androidx.core.ktx)

But the version of that library is written in libs.versions.toml

coreKtx = "1.13.1"

When to use:

Use build.gradle.kts to set up your app.

Use libs.versions.toml to manage all your library versions in one spot.