Пример работы с файлами

public class FileActivity extends AppCompatActivity {
   private static final String MY_URL = "http://testmasterfmp.fsight.cloud/";
   private static final VersionAPI MY_VERSION_API = VersionAPI.V_1;
   private static final String MY_ENVIRONMENT = "Leonid_environment";
   private static final String MY_PROJECT = "Leonid_project";
   private static final String MY_VERSION = "v1";
   private static final String MY_LOGIN = "Leonid";
   private static final String MY_PASSWORD = "123123";
   private static final String MOUNT_NAME = "nfs4";
   private static final String TAG = "FileActivity";
 
   private HyperHive hyperHive;
   private EditText editText;
   private TextView textView;
 
   @Override
   protected void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       setContentView(R.layout.activity_file);
       editText = findViewById(R.id.edit_text_file);
       editText.setText("123.txt");
       textView = findViewById(R.id.text_view_file);
 
       Handler uiHandler = new Handler();
 
       hyperHive = new HyperHiveState(getApplicationContext())
               .setHostWithSchema(MY_URL)
               .setApiVersion(MY_VERSION_API)
               .setEnvironmentSlug(MY_ENVIRONMENT)
               .setProjectSlug(MY_PROJECT)
               .setVersionProject(MY_VERSION)
               .setHandler(uiHandler)
               .buildHyperHive();
 
       authentication();
   }
 
   public void authentication() {
       boolean status = hyperHive.authAPI.auth(MY_LOGIN, MY_PASSWORD, true).execute().isOk();
       showStatus(status);
   }
 
   private void showStatus(boolean status) {
       Log.d(TAG, "status: " + status);
       Toast.makeText(this, String.valueOf(status), Toast.LENGTH_SHORT).show();
   }
 
   //1. Запросим разрешение на чтение и запись
   private void getPermissions() {
       if (ActivityCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE)
               != PackageManager.PERMISSION_GRANTED) {
           ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, 1);
       }
   }
 
   //2. Создадим файл по указанному пути «/storage/emulated/0/Download/»
   private void createFile() {
       String fullPath = "/storage/emulated/0/Download/" + editText.getText().toString();
       getPermissions();
       File file = new File(fullPath);
       try {
           file.createNewFile();
       } catch (IOException e) {
           e.printStackTrace();
       }
   }
 
   //3. Получим файл
   public void fileGet(View view) {
       createFile();
       boolean status = hyperHive.fileConnectorApi.fileGet("/storage/emulated/0/Download/" + editText.getText().toString(), editText.getText().toString(), MOUNT_NAME).execute().isOk();
       showStatus(status);
   }
 
   //4. Получим метоинформацию
   public void fileGetMeta(View view) {
       boolean status = hyperHive.fileConnectorApi.fileGetMeta(editText.getText().toString(), MOUNT_NAME).execute().isOk();
       showStatus(status);
   }
 
   //5. Отправим файл
   public void filePut(View view) {
       getPermissions();
       boolean status = hyperHive.fileConnectorApi.filePut("/storage/emulated/0/Download/" + editText.getText().toString(), editText.getText().toString(), MOUNT_NAME).execute().isOk();
       showStatus(status);
   }
 
   //6. Удалим файл
   public void fileDelete(View view) {
       boolean status = hyperHive.fileConnectorApi.fileDelete(editText.getText().toString(), MOUNT_NAME).execute().isOk();
       showStatus(status);
   }
 
   //7. Получим список файлов
   public void directoryGet(View view) {
       BaseStatus baseStatus = hyperHive.fileConnectorApi.directoryGet(".", MOUNT_NAME).execute();
       textView.setText(baseStatus.toString());
       showStatus(baseStatus.isOk());
   }
}