Inconveniencing with Mdiparent while updating Mdiparent after Load

Question

Normal 0 false false false MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:Table Normal; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:Times New Roman; mso-ansi-language:#0400; mso-fareast-language:#0400; mso-bidi-language:#0400;} Hi I just want to enable menus of Menu Strip on MdiParent after Load Mdi Form using a child form button click event. I disabled (Enable = false) those menus by default. And in case of Child form's condition comes true and then I've to turn on/Enable those menus. Problem is that once MdiParent form is loaded then I provide true value/enablev = true to MdiParent's menus from Child's click event using Mdi's Public method. In result; menus got true value but didn't implement or can say Mdi didn't get update. I also used MdiPraent.Refresh() and Many other things but it couldn't solve. I just want assistance in this issue! Thanks

Pasan Ratnayake · Answer

=] eheh. Thank you for complimenting. But compared to others in this domain of software development I am just starting. But this is what I believe in coding. There is nothing like you know to 'code'. For a fact I do not even remember any coding. All I do remember is the basics of programming and understanding how they really work. For coding all I do is solve a given problem logically and write down the logic I came up with. In case I do not know how to code my logic I read books or ask someone with more experience or of course google it. So on to your question it is a basic rule in C# that any variable must be initialized prior using it. I.e. if you create a variable you need to initialize it to a value prior using it anywhere in your code. Now in this case I have initialized the mdiParent variable in to 'null' which means nothing. Just think logically what would happen if you call a method like show() on nothing ? Doesn't make any sense even right? So you need to initialize the variable with a new MdiParent1 object. Now think about two methods which use this mdiParent variable. In the method 1 you have the initialize variable code. In the method 2 you don't have it because method 2 will never be called before method 1 according to the way you code. But think you decide to work on your code after 2 years and you accidentally call method 2 before calling method 1. Now when the method 2 is called is the variable initialized ? No right ? So that's why you always check whether a variable is null before using it. Hope this clarifies your doubt.

Mohammad Saad · Answer

Best guidance with best attitude and techniques I ever found to guide some1 from you. may God keeps you high. ameen Thank you boss :)

Mohammad Saad · Answer

thank you. I'm glade too because now able to do what i need. whenever you'll be free please tell the way I become like you and last question is why  might not be initialized to a proper value happens ???? hope will be with connected

Pasan Ratnayake · Answer

Hi again. Glad I could help you. Regarding that exception you are getting I have created a class variable of the type MdiParent1 (if you check the code of Form1 you'll see that). The problem with class variables is that they might not be initialized to a proper value when used within some other part of the code. So always just check whether it is null at the beginning of every method which calls it and initialize it if it is null. E.g.: if (this.mdiParent == null) this.mdiParent = new MdiParent1(); Hope this helps you.

Mohammad Saad · Answer

I got how it works now with the help of your Application. I appreciate your cooperate. But when i was try your code in my Application it was giving me this error:  Normal 0 false false false MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:Table Normal; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:Times New Roman; mso-ansi-language:#0400; mso-fareast-language:#0400; mso-bidi-language:#0400;} Object reference not set to an instance of an object on the time when we try to use this code in child's button click: mdiParent.fileMenu.Enabled = true;  and declare Instance for mdi in child sets like: MDIParent1 mdiParent; //as null ??? But I did it with a new Application it really works. I trace every possible mistake but didn't get yet. Can you help me in this error too...... You're right i'm new in programming n working on a assignment. Thanks

Pasan Ratnayake · Answer

Why don't you try specifying your requirement a bit more specific. Just go back and try to read your posts and think whether a person who is not you trying to read and understand your problem can understand or not? Your requirement is simple but don't take the simple facts for granted. Often they cause you rework. Personally I hate it. So please make sure you don't do that again. Anyways I've added a sample of what you might want. Hope it helps

Mohammad Saad · Answer

Normal 0 false false false MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:Table Normal; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:Times New Roman; mso-ansi-language:#0400; mso-fareast-language:#0400; mso-bidi-language:#0400;} Terrifically you're right. But should concern about that mdi is a Parent. It opens before child. Perhaps Child form has to open after the Parent. And follow the way I just want to refresh Parent's Menu Strip / Menu Items using Child's button click event. Thanks for your will. But get to the point then you'll be able to solve this query. Thanks again

Pasan Ratnayake · Answer

Hi You are doing a very fundamental programming mistake. In the code you have given you have created a MdiParent object but you have not opened that form. So how can you see whether your MDI form's menus are getting disabled/enabled? Nevertheless I've attached a simple code on how to use a MDI form and enable/disable menus. Hope you would try learning the basic programming concepts first and hope this would help you. Regards

Mohammad Saad · Answer

Normal 0 false false false MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:Table Normal; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:Times New Roman; mso-ansi-language:#0400; mso-fareast-language:#0400; mso-bidi-language:#0400;} Thanks for your consideration. now i'm giving to you a sample code. and waiting for any possibility....... \ namespace Testing { public partial class MDIParent : Form { public MDIParent() { InitializeComponent(); } public void LoadMDIParent() { //menuStrip.Enable = false; (by default) } public void ShowItem() { menuStrip.Enable = true; this.refresh(); } } } // namespace Testing { public partial class frmLogin : Form { public frmLogin() { InitializeComponent(); } private void button1_Click( object sender EventArgs e) { if (condition==true) { MDIParent mdi = new MDIParent(); mdi. ShowItem(); //Not get required result with it this.close(); } } }

Pasan Ratnayake · Answer

If what you want to do is to enable/disable menus depending on button click on a child window. Right ? This is fairly simple in most cases. However in order to help with your question please post a simple application replicating your problem and I would be happy to resolve it and upload back for your reference.