Built application files

*.apk
*.ap_

Files for the ART/Dalvik VM

*.dex

Java class files

*.class

Generated files

bin/
gen/
out/

Gradle files

.gradle/
build/

Local configuration file (sdk path, etc)

local.properties

Proguard folder generated by Eclipse

proguard/

Log Files

*.log

Android Studio Navigation editor temp files

.navigation/

Android Studio captures folder

captures/

Intellij

*.iml
.idea/workspace.xml
.idea/libraries

Keystore files

*.jks

gitignore修改无效的处理

.gitignore只能忽略那些原来没有被track的文件，如果某些文件已经被纳入了版本管理中，修改.gitignore是无效的。那么解决方法就是先把本地缓存删除（改变成未track状态），然后再提交
git rm -r --cached .
git add .
git commit -m 'update .gitignore'