I implemented a bottom navigation bar with multiple fragments. When selecting each view, I added the fragment to the back stack with transaction.addToBackStack(null). However, when I pressed the back button the fragments switched but the menu item in the navigation bar would not highlight.   Apparently, Material design guidelines state “On Android, the Back button does not navigate between bottom navigation bar views.”   As a result I needed to remove the call to addToBackStack as the proper behavior is for the back button to go to the previous app or activity.

To determine where the Android SDK folder on your computer is located open Android Studio. Press the Android Studio menu in the toolbar and search for “Android SDK” or navigate there via Appearance & Behavior, System Settings, Android SDK. The location of the folder is located in the text box near the top that says “Android SDK Location”. By default the Android SDK location is stored at “/Users/[USER]/Library/Android/sdk” or at “/Library/Android/sdk/”.

Google gives an overview of what expansion APK files are along with some sample code. However, getting started can be tricky. Here is an easier to understand set of instructions for importing the necessary libraries as modules in Android Studio. The following instructions were tested with Android Studio version 2.2.3 on a mac. Note that on a mac the Android sdk folder is at /Library/Android/sdk/ or at /Users/[USER]/Library/Android/sdk/. Download libraries Android Studio…Preferences…Appearance & Behavior…System Settings…Android SDK.

If you are used to programming in iOS and need to write an Android app or vice versa here is a list of iOS views and their equivalent views on android. You can also use this list to infer the corresponding View Controller and Activity. iOS android UITableView ListView UICollectionView GridView API’s below