When you have used Interface

This is most frequent question of interviewer ‘tell me the real scenario where you have used interface’. I would like to explain my experience where I have used Interface.

I have created a class named ‘CCommon’. In which  I have defined a method named Load(..).  The functionality of Load was to set the forms properties like.  WindowState,MaximizeBox, BackColor etc. It is required to set these properties for each form. I need to call this method for each ‘n’ every form in the project.

So I have required such object in Load function which can be used for every form. In this order I have created an Interface ICommon and implement every form from this Interface.

And defined Load method as

///

       ///

       ///

       ///

       internal void Load(ICommon objICommon)

       {                        

           objICommon.Text_Form =  ApplicationName;

           objICommon.MaximizeBox_Form = false;

          // objICommon.MinimizeBox_Form = false;

           objICommon.MinimumSize_Form = new Size(objICommon.Width_Form, objICommon.Height_Form);

           objICommon.MaximumSize_Form = new Size(objICommon.Width_Form, objICommon.Height_Form);

           objICommon.StartPos_Form = FormStartPosition.CenterScreen;                     

       }