Do I correctly understand what a class is?

Question

I\'ve had trouble finding a clear, concise laymans definition of a class. Usually, they give general ideas without specifically spelling it out, and I\'m wondering if I\'m u

Answer 1

A class is a bunch of code that defines an entity in your application. There may be many such entities, but the behaviour of each is the same, as defined by the class. The class will typically define fields, whose contents are local to the instances (or objects) of that class. It is these fields that provide the objects with state and make them distinguishable from one another.

To use your example, there might be a Button class that defines what a button is in your application. This class would then be instantiated twice to provide two objects: one for the "No" button and another for the "Yes" button. The Button class could have a Text field/property that defines what text it contains – this could be set to "No" and "Yes" on the appropriate Button instances to give them their different appearances.

As for the click behaviour of the buttons, this would typically be implemented via the observer pattern, in which the subject class (Button in this case) maintains a list of separate "observer" objects which it notifies whenever some event occurs (i.e. when the button is clicked).