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<title>Mapped superclass</title>
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<meta name="doctitle" content="Mapped superclass" />
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<div class="sect2"><!-- infolevel="all" infotype="General" -->
<h1>Mapped superclass</h1>
<p><a id="sthref85" name="sthref85"></a><a id="sthref86" name="sthref86"></a>An entity that extends a <span class="bold">Mapped Superclass</span> class inherits the persistent state and mapping information from a superclass. You should use a mapped superclass to define mapping information that is common to multiple entity classes.</p>
<p>A mapped superclass <span class="italic">can be</span>:</p>
<ul>
<li>
<p>Abstract or concrete classes</p>
</li>
</ul>
<p>A mapped superclass <span class="italic">cannot be</span>:</p>
<ul>
<li>
<p>Be queried or passed as an argument to Entity-Manager or Query operations</p>
</li>
<li>
<p>Be the target of a persistent relationship</p>
</li>
</ul>
<p>A mapped superclass does not have a defined database table. Instead, its mapping information is derived from its superclass. To override the mapping information for a specific subclass, use the <code>@AttributeOverride</code> annotation for that specific class.</p>
<p><a id="sthref87" name="sthref87"></a><a id="sthref88" name="sthref88"></a><a id="sthref89" name="sthref89"></a><a id="sthref90" name="sthref90"></a>A mapped superclass is identified by the <code>@MappedSuperclass</code> annotation.</p>
<p>Use this procedure to add Mapped Superclass persistence to an existing entity:</p>
<ol>
<li>
<p>Open the Java class in the <span class="gui-object-title">Project Explorer</span>.</p>
</li>
<li>
<p>Select the class in the JPA Structure view.</p>
</li>
<li>
<p>In the JPA Details view, click the mapping type hyperlink to open the Mapping Type Selection dialog.</p>
</li>
<li>
<p>Select <span class="bold">Mapped Superclass</span> and then <span class="bold">OK</span>.</p>
<div class="figure"><a id="sthref91" name="sthref91"></a>
<p class="titleinfigure">Mapping Type Selection Dialog (Mapped Superclass)</p>
<img src="img/mapping_type_selection_superclass.png" alt="The Mapping Type Selection dialog with Mapped Superclass selected." title="The Mapping Type Selection dialog with Mapped Superclass selected." /><br /></div>
<!-- class="figure" --></li>
<li>
<p>Complete the remaining <a href="ref_persistence_prop_view.htm#BABFAEBB">JPA Details view (for entities)</a>.</p>
</li>
</ol>
<p> </p>
<img src="img/ngrelt.png" alt="Related tasks" title="Related tasks" /><br />
<br />
<a href="task_add_persistence.htm#BABHICAI">Adding persistence to a class</a><br />
<a href="task_additonal_tables.htm#CIHGBIEI">Specifying additional tables</a><br />
<a href="task_inheritance.htm#CIHCCCJD">Specifying entity inheritance</a><br /></div>
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