How do i save the state of my GUI and load the saved state again?

I am making a program to book airline tickets. Each radio button represents a seat in the plane. I changed the color of each button when selected to indicate that the seat is occupied. This will show the next person who runs the program that he cannot select that seat............. E.g. of seat names (LW1, LW2, LW3 etc.......)

function uipanel4_SelectionChangeFcn(hObject, eventdata, handles)
A = get(hObject,'String');
switch A
    case 'LW1'     
        if (get(hObject,'Value')== get(hObject,'Max'))
            set(hObject, 'BackgroundColor','red')
        end

      case 'LW2'
          if (get(hObject,'Value')== get(hObject,'Max'))
              set(hObject, 'BackgroundColor','red')
          end
  end

How can I save the state of the buttons so that a seat cannot be selected twice?

I made an "ok" push button to carry out the save function and it didn't work. This is the code:

function ok_KeyPressFcn(hObject, eventdata, handles)
saveState(handles)

function saveState(handles)
state.radioVal = get(handles.radiobutton2,'BackgroundColor');
save ('state.mat', 'state')

function loadState(handles)
filename = 'state.mat'
if exist(filename)
    load(filename)
    set(handles.radiobutton2,'BackgroundColor', state.radioVal);
end

Answer 1

[Geoff Hayes]

Rushane - what do you mean by and it didn't work? It is sometimes helpful to provide more information. Is there an error, and if so, what is it?

If I run your code, then an error does appear as

 SWITCH expression must be a scalar or string constant.
 Error in untitled1>uipanel4_SelectionChangeFcn

This is because the data type for

 A = get(hObject,'String');

is cell. You must convert the string property of the radio button to a character array as

 A = char(get(hObject,'String'));

then the switch expression should be fine. The code to check for whether the radio button has been selected (or not) can be simplified from

 if (get(hObject,'Value')== get(hObject,'Max'))

to

 if get(hObject,'Value')

The rest should work without error provided that loadState is called from your OpeningFcn.

One thing that you may want to consider is a way to generalize the state object so that you can store the data for each radio button in a field specific to that radio button. Try using its tag as follows

 function saveState(handles)

 state = [];

 % get all fields from handles
 guiFields = fields(handles);

 % iterate through each field
 for k=1:length(guiFields)
     obj = handles.(guiFields{k});

     % if the object is a scalar AND a graphics handle and has a field
     % called Style
     if isscalar(obj) && ishghandle(obj) && isfield(get(obj),'Style')
         style = get(obj,'Style');
         if strcmpi(style,'radiobutton')
            % style is radiobutton so save its background color to the
            % state structure
            state.(guiFields{k}) = get(obj,'BackgroundColor');
         end
     end
 end

 % write the state to file
 save('state.mat','state');

The loadState function would need to change to something like

 function loadState(handles)

 filename = 'state.mat';
 if exist(filename,'file')
    load(filename);

    % get all fields from state
    stateFields = fields(state);

    % iterate through each field
    for k=1:length(stateFields)
        set(handles.(stateFields{k}),'BackgroundColor', state.(stateFields{k}));
    end
 end

[Rushane]

Thanks, this really helped me out a lot. The program ran well for the first try. But after running it a few more times, Matlab started to give this error pointing to the load state part of the code, relating to the background color which stopped it from running:

??? Error using ==> set
Color value must be a 3 element numeric vector

Error in ==> first_classseat>loadState at 415
        set(handles.(stateFields{k}),'BackgroundColor',
        state.(stateFields{k}));

Error in ==> first_classseat>first_classseat_OpeningFcn at 60
loadState(handles)

Error in ==> gui_mainfcn at 221
    feval(gui_State.gui_OpeningFcn, gui_hFigure, [],
    guidata(gui_hFigure), varargin{:});

Error in ==> first_classseat at 42
    gui_mainfcn(gui_State, varargin{:});

How can this be corrected? and

How could I make the button invisible after selected, instead of making it red? I was unable to do this.

Thank you very very much....................

[Geoff Hayes]

Rushane - put a breakpoint a the line

 set(handles.(stateFields{k}),'BackgroundColor',state.(stateFields{k}));

and then run launch your GUI. When the code pauses at the breakpoint, look at the state structure and the state.(stateFields{k}) value. What is it, and does it make sense?

As for making a radio button invisible after it has been selected, look at the Visible property of the radio button and try changing its value from on to off.

[MatLAbForGuiL]

@Geoff Hayes I love you