Editing a Form using a method in another class

Question

1.00/5 (1 vote)

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So I created a method with a switch case in it.

C#

public void FormStateSwitch(FormState formState)
{
    var defaulSize = new Size(278, 132);
    var backDefLoc = new Point(10, 77);
    switch (formState)
    {
        case FormState.Template: //Template
            optionsPanel.Visible = false;
            isbnPanel.Visible = false;
            titlePanel.Visible = false;
            templatePanel.Visible = true;
            Size = defaulSize;
            break;
        case FormState.Options: //Options
            titlePanel.Controls.Remove(_back);
            isbnPanel.Controls.Remove(_back);
            optionsPanel.Controls.Add(_back);
            isbnPanel.Visible = false;
            titlePanel.Visible = false;
            templatePanel.Visible = false;
            optionsPanel.Visible = true;
            Size = defaulSize;
            _back.Location = backDefLoc;
            _previousState = FormState.Template;
            break;
        case FormState.ISBN: //ISBN
            optionsPanel.Controls.Remove(_back);
            titlePanel.Controls.Remove(_back);
            isbnPanel.Controls.Add(_back);
            optionsPanel.Visible = false;
            titlePanel.Visible = false;
            templatePanel.Visible = false;
            isbnPanel.Visible = true;
            Size = defaulSize;
            _back.Location = backDefLoc;
            _previousState = FormState.Options;
            break;
        case FormState.Title: //Title
            isbnPanel.Controls.Remove(_back);
            optionsPanel.Controls.Remove(_back);
            titlePanel.Controls.Add(_back);
            optionsPanel.Visible = false;
            isbnPanel.Visible = false;
            templatePanel.Visible = false;
            titlePanel.Visible = true;
            _back.Location = new Point(10, 137);
            Size = new Size(278, 195);
            _previousState = FormState.Options;
            break;
    }
}

The method works fine when called within the form it is contained in, but when I call it from an outside class it has no effect. The answer is probably simple and I am overlooking something so I would appreciate the help. Even when I try to edit the form without using this method and I am working in another class it also doesn't have an effect.
I would also appreciate an explanation as to why so that I am learning something instead of just being told something.

Posted 4-May-11 17:21pm

Cardon Fry

Updated 5-May-11 17:48pm

v2

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Comments

Hemant__Sharma 5-May-11 0:30am

Did you get any exception when debugging or your code came succefully to the end of this function?
Can you add code
1- where you are invoking this function inside the same form
2- where you are invoking this function from outside class
the code should include any event name like button click etc in which you are invoking this function.

Thanks
Hemant

Cardon Fry 5-May-11 0:47am

No exceptions were made in it ran through the code completely, the form just never updated. I will edit this post with direct examples when i get back home.

3 solutions

Solution 1

- if the outside class is running some other thread than the form thrad then it will raise cross thread operation exception.

Posted 4-May-11 18:30pm

Hemant__Sharma

Solution 4

Bad switch case! Never do such things!

At least, create some enumeration and use it in case and elsewhere:

enum MyCase { Template, Options, Isbn, Title, }

In general, avoid all those immediate constants: 0, 1, "", "my string", etc. Always use explicit constant declarations, data files and/or resources.

—SA

Posted 5-May-11 9:58am

Sergey Alexandrovich Kryukov

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CodeHawkz · Accepted Answer · 2011-05-04T19:00:00

Hi there,

If I am not mistaken, what you are trying to achieve is to have multiple modes in the form like Insert, Edit, Update. There is an easier way of achieving this.

What you need to do is, drag and drop a Panel object on to your form, dock it in the form, design one state/mode. Repeat this process, for each and every state/mode you want. Then instead of, adding/removing your controls, you can show/hide them.

C#

enum FormState {
    Template,
    Options,
    ISBN,
    Title
}

public void FormStateSwitch(FormState formState) {
    switch (formState)
    {
        case FormState.Template:
            templatePanel.Visible = true;
            optionsPanel.Visible = false;
            isbnPanel.Visible = false;
            titlePanel.Visible = false;
            break;
        case FormState.Options:
            // Do your work here
            break;
        case FormState.ISBN:
            // Do your work here
            break;
        case FormState.Title:
            // Do your work here
            break;
        default:
            // Do your work here
            break;
    }
}

On a final note, please do not use int to depict your states, use an Enum instead, like I have used. There are many reasons why you should, I am going to mention only a few.
1. If you use numbers, you have to manually keep track what each mode. I.e. 1 = Template, etc. But if you use Enums, you see directly what "formState" is without remembering it. So you can use it in multiple locations without accidentally coding for a wrong state.
2. It is very easy to add/remove states. As soon as you remove a state, everywhere you've used that particular state will be highlighted as an error. As soon as you change the name of a state to something different, it will be updated all over your solution (if you are using a IDE like VS). If you add a state, all you have to do is go and add another case to your switch.
3. You can assign values to each item in an enum. For instance,

enum FormState {
    Template = 1,
    Options = 10,
    ISBN = 15,
    Title = 20
}

These are just example values but you can directly convert your enum to integer and use it in a calculation. The best part is, everything is strongly typed. You update your enum, everywhere else it would be updated.

Hope this helps :) Regards