Android Studio .gitignore template

local.properties is the rule that matters. It records the absolute path to the Android SDK on this machine, and often the NDK path too. Those paths differ on every developer's machine and between every operating system, so a committed copy causes a build failure with a confusing message about a missing SDK. It is also a place where signing configuration sometimes ends up, including a keystore password, which turns a nuisance into a leak.

This template takes a more surgical approach to the editor directory than the standalone IntelliJ one. Instead of ignoring .idea wholesale, it names specific files: caches, libraries, modules.xml, workspace.xml, navEditor.xml and assetWizardSettings.xml. Those are the machine specific ones, which leaves room for a team to track the shared code style and inspection profiles in the same directory.

/build and *.iml cover the Gradle output directory and the module descriptors. .gradle holds the build tool's own caches and daemon state. All three are regenerated, and the module files in particular are rewritten on every project sync. Tracking a module file therefore guarantees a conflict on any branch where somebody added a dependency, which is a slow way to learn what the rule was for.

.externalNativeBuild and .cxx are the working directories for native code built through the native build integration. They contain compiler output and generated build files keyed to the ABI and the toolchain installed locally. A project with no native code never sees either directory, which is why the rules are easy to overlook until the first build produces gigabytes nobody expected.

/captures is where the profiler saves recorded traces, and *.apk is the packaged application. output.json is the build output metadata file listing what was produced and with which version code, which is generated on every build. Profiler traces in particular are large and describe one run on one device, so they belong in an issue tracker attachment rather than in the repository.