Java – How to properly design classes for a big project

The one-to-many relationship between Order and Product translates as a list of Products. For example in Java Order would have a member of type List<Product>.

But I recommend having an OrderDetail class instead because you will soon find that you have to have and amount or quantity of the product, and it doesn't belong in either Order or Product.

EDIT:

In UML Order would have a "composition" which is a line with a black diamond shape on the Order side and a ">" (not a triangle) on the OrderDetail side.

If you decide to use Product instead of OrderDetail then you should have an "agregation" which has a white diamond shape.

The difference is that a composition means OrderDetail has no meaning outside an Order whereas agregation means that Products can exist by themselves outside an Order.

From what I've seen, stereotype is usually used to represent the relationship to an exception.

a better approach would be to use UML’s stereotype notation with the keyword exception as the stereotype enclosed in guillemets, as in «exception».

^{Source: How can I represent an exception in UML?}

This answer on Stack Overflow also suggests stereotypes, but uses <<throws>> instead. The author is confident that it's ok to use a stereotype which doesn't exist conventionally, and in this particular case, I agree with him.

As for the proper term, given that a stereotype can be a noun or a verb, both <<exception>> and <<throws>> seem equally correct. The proper terminology also depends on the language you use. For example in Python, you don't throw, but raise an error or an exception, so <<raises>> looks as the most appropriate one; unless your intention is to separate errors and exceptions, in which case <<exception>> and <<error>> may be more expressive.

Finally, Agile Modeling suggests (search for Figure 4) to embed the name of the exception like this:

+ findAllInstances(): Vector {exceptions=NetworkFailure, DatabaseError}

but IMO, while it's well suited for well-known exceptions used by the framework, it is too poor for custom exceptions you have created, because the relation is not visual enough.