Android Api and Related versions

Picking the full suite of android versions can be difficult if you are not a full time android developer. This document is for contributors to understand what versions of common android tooling should be used in the flutter/flutter codebase.

Overview

**The most important thing is for any test, project, or app to have compatible versions. **

If versions need to be different then a comment explaining why and what is being evaluated should be included. All chosen versions should pass the minimum versions checks defined in DependencyVersionChecker

If the versions chosen are not known by gradle_utils.dart then update gradle_utils.dart.

Specifics

compileSdk

• Must be higher then or equal to targetSdk.
• Should be compileSdk instead of compileSdkVersion.
• Should be the max stable value available in CIPD if not flutter.compileSdkVersion.
• Must have a comment if an api level lower than max is chosen intentionally.

// OK
android {
  compileSdk = flutter.compileSdkVersion
}

// OK if flutter.compileSdkVersion is not available like in an add to app example.
android {
  compileSdk = 35
}

// NOT OK
android {
  compileSdk 28
}

targetSdk

• Must be higher then or equal to minSdk.
• Should be targetSdk instead of targetSdkVersion.
• targetSdk takes human level effort to update. This is a design decision by the AGP team.
• targetSdk may lag behind compile sdk because of the effort to update.
• If the targetSdk version is intentionally different there should be a comment explaining why.

// OK
defaultConfig {
  targetSdk = flutter.targetSdkVersion
}

// OK if flutter.compileSdkVersion is not available like in an add to app example.
defaultConfig {
  targetSdk = 35
}

// NOT OK
defaultConfig {
  targetSdk 28
}

AGP

AKA com.android.application, com.android.tools.build:gradle com.android.library

• “AGP” version should be the version set in flutter templates or newer.
• If the version is intentionally different there should be a comment explaining why.

// OK
dependencies {
    classpath "com.android.tools.build:gradle:8.8.1"
}

// OK
dependencies {
    // Testing backwards compatability of feature XYZ
    classpath "com.android.tools.build:gradle:7.5.2"
}

gradle

Gradle versions are the least likley to break across minor version updates.

• In new code the “gradle” version should be the version set in flutter templates or newer.
• In older code any gradle version that works with the other version constraints is ok.
• In practice our customers use a large variety of gradle versions.
• If the version is intentionally different there should be a comment explaining why.

// OK
distributionUrl=https\://services.gradle.org/distributions/gradle-8.12.1-bin.zip

Kotlin

Changing kotlin versions is most likley to have an issue with another dependency and not the code under test.

• “kotlin” version should be the version set in flutter templates or newer.
• If the version is intentionally different there should be a comment explaining why.

// Ok
ext.kotlin_version = "1.7.10"
...
classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"

compileOptions and kotlinOptions

• sourceCompatibility must use JavaVersion.*
• targetCompatibility must use JavaVersion.*
• kotlinOptions jvmTarget should match the versions used by compileOptions or there should be a comment explaining why.
• jvmTarget should use JavaVersion..toString() or there should be a comment explaining why.

// Correct configuration
compileOptions {
    sourceCompatibility = JavaVersion.VERSION_17
    targetCompatibility = JavaVersion.VERSION_17
}

kotlinOptions {
    jvmTarget = JavaVersion.VERSION_17.toString()
}

// Not ok, kotlinOptions uses a string.
compileOptions {
    sourceCompatibility = JavaVersion.VERSION_17
    targetCompatibility = JavaVersion.VERSION_17
}

kotlinOptions {
    jvmTarget = "17"
}

// Not ok, different versions of java
compileOptions {
    sourceCompatibility = JavaVersion.VERSION_11
    targetCompatibility = JavaVersion.VERSION_11
}

kotlinOptions {
    jvmTarget = JavaVersion.VERSION_17.toString()
}