Consol Output to GUI

Dear all,

I try to get the output of the consol to the Gui. I wrote a small test which works fine for me starting it from matlab itself.

The Code (adapted it from https://de.mathworks.com/matlabcentral/answers/71078-command-window-output-to-gui) is below. I highleighted the "non-nomal" Gui stuff by the longer lines.

function varargout = testgui(varargin)
gui_Singleton = 1;
gui_State = struct('gui_Name',       mfilename, ...
                   'gui_Singleton',  gui_Singleton, ...
                   'gui_OpeningFcn', @testgui_OpeningFcn, ...
                   'gui_OutputFcn',  @testgui_OutputFcn, ...
                   'gui_LayoutFcn',  [] , ...
                   'gui_Callback',   []);
if nargin && ischar(varargin{1})
    gui_State.gui_Callback = str2func(varargin{1});
end

if nargout
    [varargout{1:nargout}] = gui_mainfcn(gui_State, varargin{:});
else
    gui_mainfcn(gui_State, varargin{:});
end
% End initialization code - DO NOT EDIT


% --- Executes just before testgui is made visible.
function testgui_OpeningFcn(hObject, eventdata, handles, varargin)
handles.output = hObject;
guidata(hObject, handles);


% --- Outputs from this function are returned to the command line.
function varargout = testgui_OutputFcn(hObject, eventdata, handles) 
update_textfield(hObject, eventdata, handles)  %--------------------------------------------------------------
varargout{1} = handles.output;


% --- Executes on button press in pushbutton1.
function pushbutton1_Callback(hObject, eventdata, handles)
clc;
handles.text2.String = get(handles.edit1,'String');
for i = 1:uint8(str2double(get(handles.edit1,'String')))
    disp(num2str(i));
    pause(0.1);
    update_textfield(hObject, eventdata, handles); % ---------------------------------------------------------
end

function update_textfield(hObject, eventdata, handles) % -----------------------------------------------------
jDesktop = com.mathworks.mde.desk.MLDesktop.getInstance;
jCmdWin = jDesktop.getClient('Command Window');
jTextArea = jCmdWin.getComponent(0).getViewport.getView;
cwText = char(jTextArea.getText);
handles.text3.String = cwText;


function edit1_Callback(hObject, eventdata, handles)

% --- Executes during object creation, after setting all properties.
function edit1_CreateFcn(hObject, eventdata, handles)
if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))
    set(hObject,'BackgroundColor','white');
end

Everthing works fine so far. But using the application builder I get the following error message

Dot indexing is not supported for variables of this type. Error in => testgui.m at line 42

By using the individual lines of the code I found that it is caused by

jTextArea = jCmdWin.getComponent(0).getViewport.getView;

Are there any ideas on how to solve that problem?