docs/collections/tutorial/collectionswithentities.html

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   6     <title>Creating Collections with Entity Bindings</title>
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  17         <p>Library Version 11.2.5.3</p>
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  21           <th colspan="3" align="center">
  22                 Creating Collections with Entity Bindings
  23         </th>
  24         </tr>
  25         <tr>
  26           <td width="20%" align="left"><a accesskey="p" href="creatingentitybindings.html">Prev</a> </td>
  27           <th width="60%" align="center">Chapter 4.
  28         Using Entity Classes
  29         </th>
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  35     <div class="sect1" lang="en" xml:lang="en">
  36       <div class="titlepage">
  37         <div>
  38           <div>
  39             <h2 class="title" style="clear: both"><a id="collectionswithentities"></a>
  40                 Creating Collections with Entity Bindings
  41         </h2>
  42           </div>
  43         </div>
  44       </div>
  45       <p>
  46     Stored map objects are created in this example in the same way
  47         as in prior examples, but using entity bindings in place of value
  48         bindings. All value objects passed and returned to the Java
  49         collections API are then actually entity objects (<code class="classname">Part</code>,
  50         <code class="classname">Supplier</code> and <code class="classname">Shipment</code>). The application no longer
  51         deals directly with plain value objects (<code class="classname">PartData</code>,
  52         <code class="classname">SupplierData</code> and <code class="classname">ShipmentData</code>).
  53 </p>
  54       <p>
  55     Since the <code class="literal">partValueBinding</code>, <code class="literal">supplierValueBinding</code>
  56         and <code class="literal">shipmentValueBinding</code> were defined as entity bindings in
  57         the prior section, there are no source code changes necessary for
  58         creating the stored map objects.
  59 </p>
  60       <a id="entity_sampleviews2"></a>
  61       <pre class="programlisting">public class SampleViews
  62 {
  63     ...
  64     public SampleViews(SampleDatabase db)
  65     {
  66         ...
  67         partMap =
  68             new StoredMap(db.getPartDatabase(),
  69                           partKeyBinding, partValueBinding, true);
  70         supplierMap =
  71             new StoredMap(db.getSupplierDatabase(),
  72                           supplierKeyBinding, supplierValueBinding, true);
  73         shipmentMap =
  74             new StoredMap(db.getShipmentDatabase(),
  75                           shipmentKeyBinding, shipmentValueBinding, true);
  76       ...
  77     } </pre>
  78       <p>
  79     Specifying an
  80     <a class="ulink" href="../../java/com/sleepycat/bind/EntityBinding.html" target="_top">EntityBinding</a>
  81
  82         will select a different
  83     <a class="ulink" href="../../java/com/sleepycat/collections/StoredMap.html" target="_top">StoredMap</a>
  84
  85         constructor, but the syntax is the same. In general, an entity
  86         binding may be used anywhere that a value binding is used.
  87 </p>
  88       <p>
  89     The following getter methods are defined for use by other
  90         classes in the example program. Instead of returning the map's
  91         entry set
  92     (<a class="ulink" href="http://download.oracle.com/javase/1.5.0/docs/api/java/util/Map.html#entrySet()" target="_top">Map.entrySet</a>),
  93         the map's value set
  94     (<a class="ulink" href="http://download.oracle.com/javase/1.5.0/docs/api/java/util/Map.html#values()" target="_top">Map.values</a>)
  95         is returned. The entry set was convenient in prior examples because
  96         it allowed enumerating all key/value pairs in the collection. Since
  97         an entity contains the key and the value, enumerating the value set
  98         can now be used more conveniently for the same purpose.
  99 </p>
 100       <a id="entity_sampleviews3"></a>
 101       <pre class="programlisting"><strong class="userinput"><code>import com.sleepycat.collections.StoredValueSet;</code></strong>
 102 ...
 103 public class SampleViews
 104 {
 105     ...
 106 <strong class="userinput"><code>    public StoredValueSet getPartSet()
 107     {
 108         return (StoredValueSet) partMap.values();
 109     }
 110
 111     public StoredValueSet getSupplierSet()
 112     {
 113         return (StoredValueSet) supplierMap.values();
 114     }
 115
 116     public StoredValueSet getShipmentSet()
 117     {
 118         return (StoredValueSet) shipmentMap.values();
 119     }</code></strong>
 120     ...
 121 } </pre>
 122       <p>
 123     Notice that the collection returned by the
 124     <a class="ulink" href="../../java/com/sleepycat/collections/StoredMap.html#values()" target="_top">StoredMap.values</a>
 125
 126         method is actually a
 127     <a class="ulink" href="../../java/com/sleepycat/collections/StoredValueSet.html" target="_top">StoredValueSet</a>
 128
 129         and not just a
 130     <a class="ulink" href="http://download.oracle.com/javase/1.5.0/docs/api/java/util/Collection.html" target="_top">Collection</a>
 131
 132         as defined by the
 133     <a class="ulink" href="http://download.oracle.com/javase/1.5.0/docs/api/java/util/Map.html#values()" target="_top">Map.values</a>
 134
 135         interface. As long as duplicate keys are not allowed, this
 136         collection will behave as a true set and will disallow the addition
 137         of duplicates, etc.
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