[android] How to get the file ID so I can perform a download of a file from Google Drive API on Android?

Well the first option I could think of is that you could send a list request with search parameters for your file, like title="File_1.xml" and fileExtension="xml". It will either return an empty list of files (there isn't one matching the serach criteria), or return a list with at least one file. If it's only one - it's easy. But if there are more - you'll have to select one of them based on some other fields. Remember that in gdrive you could have more than 1 file with the same name. So the more search parameters you provide, the better.