Editing Marker interface pattern (section)

{{Refimprove|date=June 2013}}
The '''marker interface pattern''' is a [[design pattern (computer science)|design pattern]] in [[computer science]], used with languages that provide run-time type information about objects. It provides a means to associate metadata with a class where the language does not have explicit support for such metadata.

To use this pattern, a [[Class (computer science)|class]] implements a '''marker interface'''<ref name="EffectiveJava">
{{cite book
 | last = Bloch
 | first = Joshua
 | title = Effective Java
 | page = [https://archive.org/details/effectivejava00bloc_0/page/179 179]
 | chapter = Item 37: Use marker interfaces to define types
 | year = 2008
 | isbn = 978-0-321-35668-0
 | publisher = Addison-Wesley
 | chapter-url-access = registration
 | chapter-url = https://archive.org/details/effectivejava00bloc_0/page/179
 | edition = Second
 }}</ref> (also called '''tagging interface''') which is an empty interface,<ref>{{Cite web |date=2017-03-06 |title=Marker interface in Java |url=https://www.geeksforgeeks.org/marker-interface-java/ |access-date=2022-05-01 |website=GeeksforGeeks |language=en-us}}</ref> and methods that interact with instances of that class test for the existence of the interface. Whereas a typical [[interface (computer science)|interface]] specifies functionality (in the form of method declarations) that an implementing class must support, a marker interface need not do so. The mere presence of such an interface indicates specific behavior on the part of the implementing class. Hybrid interfaces, which both act as markers and specify required methods, are possible but may prove confusing if improperly used.