Android get installed APP

StackPverflow - How do I check if an app is a non-system app in Android? 
StackPverflow - How to obtain the installed widget list? 
【Android】获取手机中已安装apk文件信息(PackageInfo、ResolveInfo)(应用图片、应用名、包名等)
 tsots的Android範例Source - PackageInfo / ApplicationInfo / ResolveInfo 的比較