I have associated my app with txt file. So user can select a file in File explorer app and select my app to open it. In OnCreate:

    Intent intent = getIntent();
    String action = intent.getAction();        
    if (action != null && action.equals(Intent.ACTION_VIEW)) {
        txtFilePath = intent.getData().getPath();
    }

However, when user did not close my app, and he goes back to file explorer and open another file, OnCreate is not called. OnResusme is called instead. I put below code in OnResume:

    Intent intent = getIntent();
    String action = intent.getAction();        
    if (action != null && action.equals(Intent.MAIN)) {
        txtFilePath = intent.getData().getPath();
    }

However, txtFilePath is null. Why? Thank a lot for help.