hold ⌘ to : close a type of warnings
hold shift and ⌘ to : close all types of warnings
** this is not documented elsewhere, and just discovered it by trying, and thought I will share it.
to list the emulators you have
for example, I have this Nexus_5X_API_24
so the command to run that emulator is
cd ~/Library/Android/Sdk/tools && ./emulator -avd Nexus_5X_API_24