This tutorial illustrates how to install the apk files manually in Android Studio Emulator.
1) Fist you need to make sure you have this directory. (X:\Program Files (x86)\Android\android-studio\sdk\platform-tools). If you don’t see this directory in your SDK, Launch your Android Studio and Open Tools->SDK Manager make sure you have the Android SDK Platform Tools installed.
Note: In some case you won’t find this directory in above path, this path you can get from Androinf SDK location in the same above screen, marked red in the below picture.
2) Copy your .apk file into (X:\Program Files (x86)\Android\android-studio\sdk\platform-tools) or whatever path in your SDK manager.
3) Go to Android Studio > Tools-> AVD Manager > Start Emulator
4) Go to Start > Run > Cmd. then
cd "C:\Program Files (x86)\Android\android-studio\sdk\platform-tools"
adb install "yourapp.apk"
You will see a success messsage after sometime in the command prompt.
Then go the emulator and you will see your app in the apps screen.