After successfully setting up an android project all of the default files are created with default code in themlet us look at this default code and files and try to run the default app created the panel on the left side of the android studio window has all the files that the app includes. Android programming concepts and build a variety of apps starting with hello world and working your way up to apps that app overview task 1 install android studio task 2 create hello world app task 3 explore the project structure and layout task 4 create a virtual device. Over the years the android api framework has evolved to become more stable intuitive and concise as a result being an android developer today is easier than ever even more so if you use android studio the official tool for working with the framework in this tutorial ill show you how to create your first android app while doing so i . In android studio select your app from the run debug configurations drop down menu in the toolbar in the toolbar select the device that you want to run your app on from the target device drop down menu figure 1 target device drop down menu click run android studio installs your app on your connected device and starts it you now see hello world displayed in the app on your device. Whats happening behind the scenes finally you have run your first helloworld app on your emulator congratulations but here are a few things that happened when you clicked the play button all your java source code gets compiled into class files by the java compiler all your class files gets converted into a single dex file by the dx tool which is the part of android sdk tools