Once you have successfully set up IntelliJ, it should then load your project with default files which it sets up. I’m going to explain what they are used for as they are essential to understand before you begin.
1. The first file you see if the res (resource). This includes three other sub files which I am going to explain individually.
1.1. The drawable-hdpi. This is where all of the images which you are going to place in your project are going to go. It is only necessary to place them in one of the files, I have chosen the highest resolution one. Android does not accept capital letters for the image names, so try to avoid doing that.
1.2. The layout folder. This is where all of the pages (activities) for your app are going to go into. You can have as many activities as you like, however the more you have the more space your’e going to use up.
To create any new page simply right click on the folder and new > layout resource file.
1.3. The values folder. Within here you can have a strings, colors and dimensions. All of the textual information, colors and sizes which you are going to use should be placed within these folders and not hardcoded within the XML activity.
2. the src file. Every activity you create should normally have a Java file to go along with it. This is if it is going to be a functional page, which they all should be.
3. The AndroidManifest. This is the last file which you are going to need to use for your app. It will already be set up, however each time you add a page you should update it accordingly. The order which the pages are placed within it do matter so, if for example you are going to have a splash screen it should come first in the manifest.