Google drive application

Google drive application

This is what i tried from google for Multiple account selector
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
credential = GoogleAccountCredential.usingOAuth2(this, DriveScopes.DRIVE);
startActivityForResult(credential.newChooseAccountIntent(),
REQUEST_ACCOUNT_PICKER);
}
But i am making an app in which i am using my Drive free space to upload
the data and i want that when user click he shoud be able to view or
download the files stored in my account.
i dont want to user select account and login. i want to give my fixed
account so on one click user can download it. It shoud automatically login
to that account so where do i specify my mail id and password.
Please suggest the code.