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| <p><a id="BABGBIEE" name="BABGBIEE"></a></p> |
| <div class="sect2"><!-- infolevel="all" infotype="General" --> |
| <h1>Entity</h1> |
| <p><a id="sthref76" name="sthref76"></a><a id="sthref77" name="sthref77"></a><a id="sthref78" name="sthref78"></a><a id="sthref79" name="sthref79"></a>An <span class="bold">Entity</span> is a persistent domain object.</p> |
| <p>An entity <span class="italic">can be</span>:</p> |
| <ul> |
| <li> |
| <p>Abstract or concrete classes. Entities may also extend non-entity classes as well as entity classes, and non-entity classes may extend entity classes.</p> |
| </li> |
| </ul> |
| <p>An entity <span class="italic">must have</span>:</p> |
| <ul> |
| <li> |
| <p>A no-arg constructor (public or protected); the entity class may have other constructors as well.</p> |
| </li> |
| </ul> |
| <p><a id="sthref80" name="sthref80"></a><a id="sthref81" name="sthref81"></a><a id="sthref82" name="sthref82"></a>Each persistent entity must be mapped to a database table and contain a primary key. Persistent entities are identified by the <code>@Entity</code> annotation.</p> |
| <p>Use this procedure to add persistence to an existing entity:</p> |
| <ol start="1"> |
| <li> |
| <p>Open the Java class in the <span class="gui-object-title">Package Explorer.</span></p> |
| </li> |
| <li> |
| <p>Select the class in the JPA Structure view.</p> |
| </li> |
| <li> |
| <p>In the <span class="gui-object-title">JPA Details</span> view, use the <span class="gui-object-action">Map As</span> field to select <span class="gui-object-action">Entity</span>.</p> |
| <div class="figure"><a id="sthref83" name="sthref83"></a> |
| <p class="titleinfigure">Selecting Entity Persistence</p> |
| <img src="img/persistence_view_entity.png" alt="Selecting entity persistence on the JPA Details view." title="Selecting entity persistence on the JPA Details view." /><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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