Mobiai Android Build

Android Build System

Expert knowledge for building Android projects with Gradle.

When to Use

• Building the app for testing or deployment
• Configuring build variants and flavors
• Troubleshooting build failures
• Managing dependencies

Build Commands

Assemble (build APK)

# Debug APK (default flavor)
./gradlew assembleDebug

# Specific flavor
./gradlew assemble<Flavor>Debug
# Example: ./gradlew assembleFreeDebug

# Release APK
./gradlew assemble<Flavor>Release

# App Bundle (for Play Store)
./gradlew bundle<Flavor>Release

Compile Check (fast, no APK)

Use this to quickly verify code compiles without building a full APK:

./gradlew compile<Flavor>DebugKotlin --no-daemon

Run Unit Tests

./gradlew test<Flavor>DebugUnitTest --no-daemon

Run Instrumented Tests

./gradlew connected<Flavor>DebugAndroidTest

Clean Build

./gradlew clean assembleDebug

Build Variants

Android builds are a combination of Build Type × Product Flavor.

Build Types

• debug — debuggable, no minification, debug signing
• release — minified (R8/ProGuard), release signing

Product Flavors

Flavors are defined in app/build.gradle(.kts) under productFlavors. Common patterns:

// Example: country-based flavors
flavorDimensions += "country"
productFlavors {
    create("arg") { dimension = "country"; applicationIdSuffix = ".arg" }
    create("mx")  { dimension = "country"; applicationIdSuffix = ".mx" }
}

To find available flavors:

grep -r "productFlavors" app/build.gradle* --include="*.gradle*" -A 20

Or list all build variants:

./gradlew tasks --all | grep assemble

APK Installation

# Single APK
adb install -r app/build/outputs/apk/<flavor>/debug/app-<flavor>-debug.apk

# Split APKs (when using multiple APK output)
adb install-multiple app-base.apk app-config.apk

# Replace existing installation
adb install -r <path-to-apk>

Version & Branch Management

Projects often use branch naming conventions tied to versions:

# Check available release branches
git branch -r | grep release

# Common patterns:
# release/v3.2.x
# release/3.2.0
# release/1.0.0-rc1

To build a specific version:

1. Determine the branch name from version info
2. git checkout <branch>
3. Build as normal

Dependency Management

Check for dependency issues

./gradlew dependencies --configuration <flavor>DebugRuntimeClasspath

Force a dependency version

configurations.all {
    resolutionStrategy.force("com.example:library:1.2.3")
}

Troubleshooting Common Build Failures

Out of memory

# In gradle.properties
org.gradle.jvmargs=-Xmx4g -XX:MaxMetaspaceSize=1g

Cache corruption

./gradlew clean
rm -rf .gradle/
rm -rf ~/.gradle/caches/

Kotlin version mismatch

# Check Kotlin version
grep -r "kotlin" gradle/libs.versions.toml build.gradle* --include="*.toml" --include="*.gradle*" | grep version

JDK version issues

# Check which JDK Gradle uses
./gradlew --version

# Set JDK explicitly
export JAVA_HOME=/path/to/jdk

Signing

Debug signing

Automatic — uses ~/.android/debug.keystore

Release signing

Usually configured in app/build.gradle(.kts):

grep -r "signingConfigs" app/build.gradle* -A 10

Never commit signing credentials to git.

ProGuard / R8

Check if minification is enabled

grep -r "isMinifyEnabled\|minifyEnabled" app/build.gradle* --include="*.gradle*"

Keep rules

Located in proguard-rules.pro or consumer-rules.pro. Common issues:

• Serialization classes stripped → add @Keep or keep rules
• Reflection targets removed → add keep rules
• Enum values stripped → add keep rules for enum classes