How to set initial value to an attribut for an entity and using @ReadOnly annotation?

Hi there,

I want to declare an attribut of an entity with @ReadOnly.
But, I want, that this attribut get an initial value, when I create this attribute AND, if I modify it, that it will also change the value of attribut, depending on other attributes…

For this, I would like to use the
protected void initNewItem(Item item) Method…

Does anybody have an idea?

Thanks a lot

Could you clarify this? An example project would help.