Android build and debug tips: jenv, ADB, and wireless debugging

A few of the environment quirks that come up repeatedly in Android development: juggling JDK versions, getting ADB to talk to a device over WiFi instead of a cable, and building release APKs without recreating the signing setup from memory each time.

Java version management with jenv

Android tooling is picky about JDK version, and juggling that against whatever else needs a different JDK is easier with jenv than with manually edited JAVA_HOME exports:

brew install openjdk@11
brew install jenv

# ~/.zshrc or ~/.bashrc
export PATH="$HOME/.jenv/bin:$PATH"
eval "$(jenv init -)"

jenv add /opt/homebrew/opt/openjdk@11/libexec/openjdk.jdk/Contents/Home
jenv versions
jenv global 11.0
jenv local 11.0   # per-project override

USB and wireless debugging

Enable Developer Options (Settings → About Phone → tap Build Number seven times), then USB Debugging under Developer Options. Confirm the device shows up:

adb devices
adb shell getprop ro.product.model

Wireless debugging still needs a USB cable for the initial handshake:

adb tcpip 5555
adb shell ip addr show wlan0
adb connect <device-ip>:5555
adb devices

For React Native, forward Metro’s port back to the device instead of relying on the WiFi connection for bundle serving:

npx react-native start
adb reverse tcp:8081 tcp:8081

Debug and release builds

./gradlew assembleDebug
adb install app/build/outputs/apk/debug/app-debug.apk

Release builds need signing configured once, in android/app/keystore.properties:

storeFile=your-key.keystore
storePassword=your-store-password
keyAlias=your-key-alias
keyPassword=your-key-password

./gradlew assembleRelease
cd android/app/build/outputs/apk/release
adb install app-release.apk

Logs and common failures

adb logcat | grep "com.yourpackage"
adb logcat *:E                        # errors only
adb logcat > logfile.txt

Two failure modes come up often enough to have a standard fix. Metro serving stale bundles:

npx react-native start --reset-cache
cd android && ./gradlew clean

And ADB losing the device after a sleep/wake cycle:

adb kill-server
adb start-server

Memory profiling

Android Studio’s Profiler (View → Tool Windows → Profiler) covers most of this visually. From the command line:

adb shell dumpsys meminfo <package-name>
adb shell am dumpheap <process-name> /data/local/tmp/heap.hprof

None of these are exotic. They’re just the handful of commands that are easy to forget between the times you actually need them.