google.api.client get null from file

Question

I'm trying to get some data from an existing file in google drive. The search correctly returns me some metadata, but when I try to get the date of the last modification of the file, I get null. I do not understand
This is a part of my code:

FileList result = null;
        try {
            result = mService.files().list()
                    .setQ("name = file.db and trashed = false")
                    .execute();
        } catch (IOException e) {
            e.printStackTrace();
        }
 Log.d("Sync_drive", result);
 List<com.google.api.services.drive.model.File> files;
  if (result != null) {
  for (com.google.api.services.drive.model.File fileD : files) {
 dateModified = String.valueOf(fileD.getModifiedTime().getValue());
 gdid = fileD.getId();
 Log.d("Sync_drive", "id: " + gdid);
 }

result:

Sync_drive: {"files":[{"id":"1jX2w7F0Pjx28ug0lvjEIp4Kje6fw5JyF","kind":"drive#file","mimeType":"application/octet-stream","name":"file.db"}],"incompleteSearch":false,"kind":"drive#fileList"}

and

Process: PID: 27987 java.lang.NullPointerException: Attempt to invoke virtual method 'long com.google.api.client.util.DateTime.getValue()' on a null object reference

Answer 1

you first need to connect to google client: here is an example :

protected synchronized void buildGoogleApiClient() {
        if (checkPlayServices()) {
                    .requestServerAuthCode(BuildConfig.GOOGLE_WEB_CLIENT_ID)
                    .requestEmail()
                    .build();
            // Build a GoogleApiClient with access to the Google Sign-In API and the
            // options specified by gso.
            mGoogleApiClient = new GoogleApiClient.Builder(this)
                    .addConnectionCallbacks(this)
                    .addOnConnectionFailedListener(this)
                    .addApi(/*Api for google Drive*/)
                    .enableAutoManage(this, this)
                    .build();
            mGoogleApiClient.connect();

        }
    }

you also have to implement callback functions in the same activity: , GoogleApiClient.OnConnectionFailedListener, GoogleApiClient.ConnectionCallbacks

once client is connected ,you can get data from file