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operator == method - Object class - dart:core library - Dart API
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The overriding method must still be an equivalence relation. That is, it must be:</p> <ul> <li> <p>Total: It must return a boolean for all arguments. It should never throw.</p> </li> <li> <p>Reflexive: For all objects <code>o</code>, <code>o == o</code> must be true.</p> </li> <li> <p>Symmetric: For all objects <code>o1</code> and <code>o2</code>, <code>o1 == o2</code> and <code>o2 == o1</code> must either both be true, or both be false.</p> </li> <li> <p>Transitive: For all objects <code>o1</code>, <code>o2</code>, and <code>o3</code>, if <code>o1 == o2</code> and <code>o2 == o3</code> are true, then <code>o1 == o3</code> must be true.</p> </li> </ul> <p>The method should also be consistent over time, so whether two objects are equal should only change if at least one of the objects was modified.</p> <p>If a subclass overrides the equality operator, it should override the <a href="../../dart-core/Object/hashCode.html">hashCode</a> method as well to maintain consistency.</p> </section> <section class="summary source-code" id="source"> <h2><span>Implementation</span></h2> <pre class="language-dart"><code class="language-dart">external bool operator ==(Object other);</code></pre> </section> </div> <!-- /.main-content --> <div id="dartdoc-sidebar-left" class="sidebar sidebar-offcanvas-left"> <!-- The search input and breadcrumbs below are only responsively visible at low resolutions. --> <header id="header-search-sidebar" class="hidden-l"> <form class="search-sidebar" role="search"> <input type="text" id="search-sidebar" autocomplete="off" disabled class="form-control typeahead" placeholder="Loading search..."> </form> </header> <ol class="breadcrumbs gt-separated dark hidden-l" id="sidebar-nav"> <li><a href="../../index.html">Dart</a></li> <li><a href="../../dart-core/dart-core-library.html">dart:core</a></li> <li><a href="../../dart-core/Object-class.html">Object</a></li> <li class="self-crumb">operator == method</li> </ol> <h5>Object class</h5> <div id="dartdoc-sidebar-left-content"></div> </div><!--/.sidebar-offcanvas--> <div id="dartdoc-sidebar-right" class="sidebar sidebar-offcanvas-right"> </div><!--/.sidebar-offcanvas--> </main> <footer> <span class="no-break"> Dart 3.5.4 </span> <span class="glue-footer"> <span class="no-break"> | <a href="https://dart.dev/terms" title="Terms of use">Terms</a> </span> <span class="no-break"> | <a href="https://policies.google.com/privacy" target="_blank" rel="noopener" title="Privacy policy" class="no-automatic-external">Privacy</a> </span> <span class="no-break"> | <a href="https://dart.dev/security" title="Security philosophy and practices">Security</a> </span> <div class="copyright" style="font-size: 0.9em; color: darkgrey; margin-top: 0.5em;"> Except as otherwise noted, this site is licensed under a <a style="color: darkgrey;" href="https://creativecommons.org/licenses/by/4.0/"> Creative Commons Attribution 4.0 International License</a> and code samples are licensed under the <a style="color: darkgrey;" href="https://opensource.org/licenses/BSD-3-Clause" class="no-automatic-external"> 3-Clause BSD License</a> </div> </span> </footer> <script src="../../static-assets/highlight.pack.js?v1"></script> <script src="../../static-assets/docs.dart.js"></script> <button aria-hidden="true" class="glue-footer__link glue-cookie-notification-bar-control"> Cookies management controls </button> <script src="https://www.gstatic.com/glue/cookienotificationbar/cookienotificationbar.min.js" data-glue-cookie-notification-bar-category="2B"> </script> </body> </html>