Below are some of the most common UML elements that you will see, while it does not cover all of the possible UML elements and scenarios in the universe, it does provide a quick reference for you to understand the meaning of the class diagrams.
The diagram above shows a class named ClassA with private variable FieldB of type int and MethodC. The minus sign (-) means that its private, while the positive sign (+) means that its public.
The diagram above shows an interface named InterfaceA, depicted by the text <<interface>> at the top. This means InterfaceA has a property FieldB of type int and a method named MethodC.
The diagram above shows interface implementation, depicted by the triangular arrow and the dashed line. This means that ClassB implements all of the signatures (such as properties, methods, events) of InterfaceA.
The diagram above shows class inheritance, depicted by the triangular arrow and the solid line. This means ClassB is a child of ClassA.
The diagram above shows aggregation, depicted by the hollow diamond. This means that ClassA contains ClassB and when ClassA is destroyed ClassBcan still exist in the application.
The diagram above shows composition, depicted by the solid diamond. This means that ClassA contains ClassB and when ClassA is destroyed ClassBcan no longer exist in the application.
The diagram above shows association, depicted by a line between the two classes. This means that ClassA and ClassB has a relationship with each other.
The diagram above shows a role, depicted by the +Manager text in the association. This means that ClassA is the manager of ClassB.
The diagram above shows a directed association, depicted by an arrow going from ClassA to ClassB. This means that ClassA can access ClassB, butClassB cannot access ClassA.
The diagram above shows multiplicity, depicted by the (1..*) symbol. The (1..*) means 1 to many. It means that for every instance of ClassA there can be 1 or more instances of ClassB associated with ClassA