Are these UML diagrams correct?

Question

Are these diagrams correct? I am talking just about UML specifications. The first one is a class diagram of a code implementation. The second one is an activity diagram showing how to repair some 3D models.

Answer 1

The diagrams look good, although there are a few minor errors:

1. GameObject is used as a type, but not defined. You will have to define it as a class, an interface or a data type.
2. List<...> is not correct. In UML, use the multiplicity *, as follows: - NPCs : GameObject[*]
3. In the activity diagram, the labels along flows leaving a decision should be between square brackets, e.g. [yes] and [no].
4. There is a merge symbol missing before search for holes. If an action has two incoming flows, this means that the action is executed after all incoming flows have been followed, but in your case, you want the action to be executed after one of the three flows has been followed.

One final remark: you didn't specify any multiplicities for the association between Character_Controller and Teleporter. This is okay, but it means that the multiplicities are undefined, i.e. it is not specified to how many instances of Teleporter a Character_Controller is associated and it is not specified to how many instances of Character_Controller a Teleporter is associated. Since you did specify multiplicities for the aggregations, I would advise to specify multiplicities here as well.