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Marker interface pattern

design pattern in computer science

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Record originEnglish Wikipedia
Text licenseCC BY-SA 4.0
Source revisionSep 3, 2025
Entity authorityQ1900757 ↗
Source-derived summary

The marker interface pattern is a 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 implements a marker interface (also called tagging interface) which is an empty interface, and methods that interact with instances of that class test for the existence of the interface. Whereas a typical 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.

Example

An example of the application of marker interfaces from the Java programming language is the Serializable interface:A class implements this interface to indicate that its non-transient data members can be written to an ObjectOutputStream. The ObjectOutputStream private method writeObject0(Object,boolean) contains a series of instanceof tests to determine writeability, one of which looks for the Serializable interface. If any of these tests fails, the method throws a NotSerializableException.

Critique

One problem with marker interfaces is that, since an interface defines a contract for implementing classes, and that contract is inherited by all subclasses, a marker cannot be "unimplemented".

Editorial summary

This brief starts where responsible research should: with the source description of “Marker interface pattern” as design pattern in computer science. Everything that follows is an evidence route, not borrowed authority.

Editorial reviewA concise reference frame for defining the subject, testing terminology and identifying the institution closest to the evidence. The current 237-word lead offers orientation but no explicit four-digit date, so chronology should not be assumed. The selected authority fields contribute no independent date. The account is most persuasive where Marker, interface and pattern can be independently traced.
Editorial analysis

Why this record matters

The subject matters to the general reference register because the source frames it as design pattern in computer science. Its deeper value depends on whether names, dates, institutions and citations support that framing.

Evidence profile

The citation trail is more important than the brevity of the summary: it shows where individual claims can be examined in context. The source revision retrieved here is dated Sep 3, 2025. The linked authority identifier is Q1900757. None of the 0 selected statements returned an explicit reference.

Critical limits

Overview language is designed for orientation and should not be treated as a substitute for the evidence cited beneath it. The source lead contains qualifying language; that uncertainty should survive quotation, summary and reuse. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.

How to read it

Use the entry as an orientation point, then follow its citations and revision history. Names, dates and institutional relationships should be checked against the original record.

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Three-step research path

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  2. Expand the search: follow Marker interface pattern primary sources, Marker interface pattern archive and Marker research across catalogues and specialist indexes.
  3. Test the account: compare the strongest cited source with the responsible institution’s current record and note any disagreement.

Questions for further research

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Source & attribution

This entry incorporates text from “Marker interface pattern” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.