Keys for debugging:
Press the F8 key if we want to move to the next line.
Press the F7 key if you want to go inside the method.
Press the F9 key if you want to continue executing the program.

[1] Select Android Virtual Appliance
   I'm using "My Nexus 5 API 27" created his own virtual device Android ...

[2] Launching the project
   To start, click on the menu Run → Debug 'app'.

[3] Select the tab Emulator
   To see the phone emulator

 
Note!
Press the F8 key if we want to move to the next line.
Press the F7 key if you want to go inside the method.
Press the F9 key if you want to continue executing the program.