Association (object-oriented programming)

In <a href="/facts/Object-oriented_programming/TxNMEcao">object-oriented programming</a>, association defines a relationship between classes of objects that allows one object instance to cause another to perform an action on its behalf. This relationship is <a href="/facts/Unified_Modeling_Language/3tlNS0tH">structural</a>, because it specifies that objects of one kind are connected to objects of another and does not represent <a href="/facts/Unified_Modeling_Language/3tlNS0tH">behaviour</a>.

In generic terms, the <a href="/facts/Causality/Swh496X7">causation</a> is usually called "sending a message", "invoking a <a href="/facts/Method_(computer_science)/8kAXxVYs">method</a>" or "calling a <a href="/facts/Member_function/8kAXxVYs">member function</a>" to the controlled object. Concrete implementation usually requires the requesting object to invoke a method or member function using a <a href="/facts/Reference_(computer_science)/1vm2Bph1">reference</a> or pointer to the memory location of the controlled object.
The objects that are related via the association are considered to act in a <a href="/facts/Role_(computer_science)/VJhGQ5Qe">role</a> with respect to the association, if object's current state in the active situation allows the other associated objects to use the object in the manner specified by the role. A role can be used to distinguish two objects of the same class when describing its use in the context of the association. A role describes the public aspects of an object with respect to an association.
The ends of the association can have all the characteristics of a property:

<ul><li>They can have a multiplicity, expressed by a lower and an upper limit in the form of "lowerLimit..upperLimit".</li>
<li>You can have a name.</li>
<li>You can declare a visibility.</li>
<li>You can specify whether the end of the association is ordered and / or unique.</li></ul>

Association (object-oriented programming) open-in-new

Association (object-oriented programming)