A sample .gitignore file can look like one below for a Android Studio project
# built application files
*.apk
*.ap_
# files for the dex VM
*.dex
# Java class files
*.class
# generated files
bin/
gen/
# Local configuration file (sdk path, etc)
local.properties
#Eclipse
*.pydevproject
.project
.metadata
bin/**
tmp/**
tmp/**/*
*.tmp
*.bak
*.swp
*~.nib
local.properties
.classpath
.settings/
.loadpath
YourProjetcName/.gradle/
YourProjetcName/app/build/
*/YourProjetcName/.gradle/
*/YourProjetcName/app/build/
# External tool builders
.externalToolBuilders/
# Locally stored "Eclipse launch configurations"
*.launch
# CDT-specific
.cproject
# PDT-specific
.buildpath
# Proguard folder generated by Eclipse
proguard/
# Intellij project files
*.iml
*.ipr
*.iws
.idea/
/build
build/
*/build/
*/*/build/
*/*/*/build/
*.bin
*.lock
YourProjetcName/app/build/
.gradle
/local.properties
/.idea/workspace.xml
/.idea/libraries
.DS_Store
.gradle/
app/build/
*app/build/
# Local configuration file (sdk path, etc)
local.properties
/YourProjetcName/build/intermediates/lint-cache/api-versions-6-23.1.bin
appcompat_v7_23_1_1.xml
projectFilesBackup
build.gradle
YourProjetcName.iml
YourProjetcName.iml
gradlew
gradlew.bat
local.properties
settings.gradle
.gradle
.idea
android
build
gradle