Class diagram#Multiplicity

Multiplicity ( multiplicity engl. ) denotes an interval of non -negative integers in the Unified Modeling Language ( UML), a modeling language for software and other systems. The interval is determined by a lower and an upper limit. For a model element of UML, which has a multiplicity, most often true, that it can hold values ​​or objects a number, the actual number must be greater than or equal to the lower and less than or equal to the upper limit of the multiplicity. As an upper limit, the value is permitted without restriction.

The multiplicity is often given as under esch ranke .. upper barrier, where * is at the upper bound on the value of unlimited and * is often used as an abbreviation for 0. *. under esch cirrus must be less than or equal to upper barrier. The fact that both bounds are 0 or unlimited, is not allowed. This is not the case, but both limits the same, so only the upper bound can be specified.

An element with multiplicity 0 to 1 is referred to as optional. A polyvalent element is an element having an upper limit greater than 1 In the case of a polyvalent element can be used to specify whether the values ​​of the item ordered ( isOrdered ) or not. The default value is disordered. Next, you can specify whether the values ​​of an element value can be represented more than once ( isUnique ).

Elements such as the attribute parameter, associations or the pin have a multiplicity. In the first two, the multiplicity is shown in square brackets after the name or type, such as children [0. *].

Differences to the UML 1.4

The concept of multiplicity has been simplified in the UML2. In UML 1.4, a multiplicity of several disjoint intervals could consist, for example, 0 .6, 9. *, Ie of all numbers without 7 and 8 in the UML2 several areas with a lower and an upper bound are no longer possible. The multiplicity must consist of exactly one contiguous interval.

Swell

• UML language unit