android-debug

name	android-debug
description	Debug Android Flutter apps including runtime errors, build issues, device connection problems, and performance issues. Use when troubleshooting Android-specific problems, crashes, or deployment issues.

Android App Debugging Skill

Expert guidance for debugging Android Flutter applications, covering runtime errors, build issues, device connectivity, and performance problems.

When to Use This Skill

• App crashes or runtime errors on Android
• Build failures in Android-specific code
• Device/emulator connection issues
• Performance problems (lag, memory, battery)
• Platform channel issues
• Native Android integration bugs
• APK/App Bundle generation problems

Debugging Workflow

1. Identify the Problem Type

Runtime Errors: App crashes, exceptions, unexpected behavior Build Errors: Gradle failures, dependency conflicts, compilation errors Device Issues: Cannot connect, not detecting device Performance Issues: Slow UI, memory leaks, battery drain

2. Gather Information

# Check Flutter doctor
flutter doctor -v

# List connected devices
flutter devices

# Run with verbose logging
flutter run --verbose

# Check Android logcat
flutter logs
# Or directly: adb logcat

3. Common Debug Commands

Device Connection

# List connected devices
adb devices

# Restart adb server
adb kill-server
adb start-server

# Connect to device over network
adb connect <device-ip>:5555

# Check device info
adb shell getprop ro.build.version.release

App Debugging

# Install debug APK
flutter install

# Run with debug logging
flutter run -d <device-id> --verbose

# Hot reload
r (in running flutter session)

# Hot restart
R (in running flutter session)

# View performance overlay
P (in running flutter session)

Log Analysis

# Filter logs by app
flutter logs | grep -i "flutter"

# Android-specific logs
adb logcat -s flutter

# Clear logs
adb logcat -c

# Save logs to file
adb logcat > debug.log

4. Common Issues and Solutions

Build Failures

Issue: Gradle build fails

# Clean and rebuild
flutter clean
cd android
./gradlew clean
cd ..
flutter pub get
flutter build apk

Issue: Dependency conflicts

# Check dependencies
cd android
./gradlew app:dependencies

# Update Gradle
cd android
./gradlew wrapper --gradle-version=8.0

Issue: Java version mismatch

# Check Java version (should be 17)
java -version

# Set JAVA_HOME if needed
export JAVA_HOME=/path/to/java17

Runtime Crashes

Issue: App crashes on startup

1. Check logs: flutter logs
2. Look for stack traces
3. Check AndroidManifest.xml permissions
4. Verify minimum SDK version in android/app/build.gradle.kts

Issue: Platform channel errors

1. Verify method names match between Dart and Kotlin/Java
2. Check parameter types are compatible
3. Add null safety checks
4. Review platform-specific code in android/app/src/main/kotlin/

Performance Issues

Issue: UI lag or jank

# Run in profile mode
flutter run --profile

# Enable performance overlay
flutter run --profile --trace-skia

Issue: Memory leaks

1. Use Flutter DevTools Memory tab
2. Check for retained references
3. Dispose controllers properly
4. Review image caching

Issue: Large APK size

# Analyze size
flutter build apk --analyze-size

# Enable R8 shrinking (already enabled in template)
# Check android/app/build.gradle.kts

5. Using Flutter DevTools

# Open DevTools
flutter pub global activate devtools
flutter pub global run devtools

# Or run automatically
flutter run --devtools

DevTools Features:

• Inspector: Widget tree visualization
• Timeline: Performance profiling
• Memory: Heap snapshots and leak detection
• Network: HTTP request monitoring
• Logging: Real-time log viewing
• Debugger: Breakpoints and step debugging

6. Android-Specific Debug Tools

Android Studio

1. Open android/ folder in Android Studio
2. Use Android Profiler for deep analysis
3. Run layout inspector
4. Use APK Analyzer

ADB Commands

# Take screenshot
adb shell screencap /sdcard/screen.png
adb pull /sdcard/screen.png

# Record screen
adb shell screenrecord /sdcard/demo.mp4

# Get app info
adb shell dumpsys package com.cmwen.min_flutter_template

# Force stop app
adb shell am force-stop com.cmwen.min_flutter_template

# Clear app data
adb shell pm clear com.cmwen.min_flutter_template

# Monitor CPU usage
adb shell top | grep flutter

Common Error Patterns

Gradle Errors

• Solution: Clean build, check Java version, update dependencies
• Files to check: android/build.gradle.kts, android/app/build.gradle.kts

Permission Errors

• Solution: Add permissions to AndroidManifest.xml
• File: android/app/src/main/AndroidManifest.xml

Native Code Errors

• Solution: Check Kotlin/Java code in platform channels
• Files: android/app/src/main/kotlin/

Resource Errors

• Solution: Check drawable/mipmap resources
• Files: android/app/src/main/res/

Best Practices

1. Always check Flutter doctor first: flutter doctor -v
2. Use verbose logging: flutter run --verbose or flutter build apk --verbose
3. Clean before rebuild: flutter clean when in doubt
4. Check device connection: flutter devices and adb devices
5. Read full stack traces: Don't just look at the first error
6. Test on multiple Android versions: Emulators for API 21, 29, 33+
7. Use profile mode for performance: flutter run --profile
8. Enable DevTools: Best for deep debugging

Quick Troubleshooting Checklist

• Run flutter doctor -v - all green?
• Run flutter clean && flutter pub get
• Check adb devices - device connected?
• Check Java version - is it 17?
• Review error logs - full stack trace?
• Try on different device/emulator
• Check android/app/build.gradle.kts config
• Verify AndroidManifest.xml settings
• Test with flutter run --verbose
• Use DevTools for deep analysis

Additional Resources

• Flutter Debugging Docs
• Android Developer Debug Guide
• Flutter DevTools
• ADB Reference