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

I am working on an Android project and I am trying to make use of the Google Drive API and I've got most of it working but I am having an issue in how I perform a download.

I can't find anywhere how I get the file ID so that I can perform the download. In order to test I've retrieved all files in my drive account and added them to a list array and then got the ID for the first file in the list.

I then copied the file ID in to the command to download the file and this worked successfully but I have no idea how to get the file id of the specific file I want to download.

Below is the code I am using to download the file.

private void downloadFile()
{
    Thread thread = new Thread(new Runnable() {

        @Override
        public void run() {
            try 
            {
                com.google.api.services.drive.model.File file = service.files().get("0B-Iak7O9SfIpYk9zTjZvY2xreVU").execute();
                //FileList file = service.files().list().execute();
                //List<com.google.api.services.drive.model.File> fileList = file.getItems();
                //com.google.api.services.drive.model.File fileItem = fileList.get(0);
                //Log.d("FileID" , fileItem.getId());
                //Log.d("Count", "Retreived file list");
                if (file.getDownloadUrl() != null && file.getDownloadUrl().length() > 0)
                {
                    HttpResponse resp = service.getRequestFactory().buildGetRequest(new GenericUrl(file.getDownloadUrl())).execute();
                    InputStream inputStream = resp.getContent();
                    writeToFile(inputStream);
                }
            } 
            catch (IOException e)
            {
                Log.e("WriteToFile", e.toString());
                e.printStackTrace();
            }
        }
    });
    thread.start();
}

0B-Iak7O9SfIpYk9zTjZvY2xreVU is the file ID of the file that I download which I retrieved when I did a list and selected the first file, but how can I say I want to download, File_1 and get its ID to then pass this to the service.get().execute function.

Basically my end goal is within my app, I upload an XML file to Google Drive, and then later on Download the file. It will only be one file and will always have the same name. Am I going about it the right away or is there a better way to achieve what I am trying to do?

If you know the the name of the file and if you always want to download that specific file, then you can easily get the ID and other attributes for your desired file from: https://developers.google.com/drive/v2/reference/files/list (towards the bottom you will find a way to run queries). In the q field enter title = 'your_file_name' and run it. You should see some result show up right below and within it should be an "id" field. That is the id you are looking for.

You can also play around with additional parameters from: https://developers.google.com/drive/search-parameters

One way is to associating unique properties with your file while creation.

properties = "{ \
    key='somekey' and \
    value='somevalue'
}"

then create a query.

query = "title = " + "\'" + title + "\'" + \
        AND + "mimeType = " + "\'" + mimeType + "\'" + \
        AND + "trashed = false" + \
        AND + "properties has " + properties

All the file properties(title, etc) already known to you can go here + properties.

Click with the right mouse button on the file in your Google Drive. Choose the option to get a link which can be shared from the menu. You will see the file id now. Don't forget to undo the share.

Stan0 intial idea is not a good idea. There can be multiple files with the same name. Very error prone implementation. Stan0's second idea is the correct way.

When you first upload the file to google drive store its id (in SharedPreferences is probably easiest) for later use

ie.

file= mDrive.files().insert(body).execute();      //initial insert of file to google drive

whereverYouWantToStoreIt= file.getId(); //now you have the guaranteed unique id 
                                        //of the file just inserted. Store it and use it 
                                        //whenever you need to fetch this file

This script logs all the file names and ids in the drive:

// Log the name and id of every file in the user's Drive
function listFiles() {
  var files = DriveApp.getFiles();
  while ( files.hasNext() ) {
    var file = files.next();
    Logger.log( file.getName() + ' ' + file.getId() );
  }
}  

Also, the "Files: list" page has a form at the end that lists the metadata of all the files in the drive, that can be used in case you need but a few ids.

In my opinion the easiest and fastest way to get a Google Drive file ID is from Google Drive on the web. Right-click the file name and select Get shareable link. The last part of the link is the file ID. Then you can cancel the sharing.