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		Using Entities with Collections
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		Using Entities with Collections
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          <td width="20%" align="left"><a accesskey="p" href="collectionswithentities.html">Prev</a> </td>
          <th width="60%" align="center">Chapter 4. 
        Using Entity Classes	
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            <h2 class="title" style="clear: both"><a id="entitieswithcollections"></a>
		Using Entities with Collections
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      <p>
    In this example entity objects, rather than key and value
	objects, are used for adding and enumerating the records in a
	collection. Because fewer classes and objects are involved, adding
	and enumerating is done more conveniently and more simply than in
	the prior examples.
</p>
      <p>
    For adding and iterating entities, the collection of entities
	returned by 
    <a href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/Map.html#values" target="_top">Map.values</a>
    
	is used. In general, when using an entity binding, all Java
	collection methods that are passed or returned a value object will
	be passed or returned an entity object instead.
</p>
      <p>
    The <tt class="classname">Sample</tt> class has been changed in this example to add
	objects using the 
    <a href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/Set.html#add" target="_top">Set.add</a>
    
	method rather than the 
    <a href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/Map.html#put" target="_top">Map.put</a>
    
	method that was used in the prior examples. Entity objects are
	constructed and passed to 
    <a href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/Set.html#add" target="_top">Set.add</a>.
</p>
      <a id="entity_addsuppliers"></a>
      <pre class="programlisting">import java.util.Set;
...
public class Sample
{
    ...
    private void addSuppliers()
    {
<b class="userinput"><tt>        Set suppliers = views.getSupplierSet();
        if (suppliers.isEmpty())
        {
            System.out.println("Adding Suppliers");
            suppliers.add(new Supplier("S1", "Smith", 20, "London"));
            suppliers.add(new Supplier("S2", "Jones", 10, "Paris"));
            suppliers.add(new Supplier("S3", "Blake", 30, "Paris"));
            suppliers.add(new Supplier("S4", "Clark", 20, "London"));
            suppliers.add(new Supplier("S5", "Adams", 30, "Athens"));
        }</tt></b>
    }

private void addParts()
    {
<b class="userinput"><tt>        Set parts = views.getPartSet();
        if (parts.isEmpty())
        {
            System.out.println("Adding Parts");
            parts.add(new Part("P1", "Nut", "Red",
                      new Weight(12.0, Weight.GRAMS), "London"));
            parts.add(new Part("P2", "Bolt", "Green",
                      new Weight(17.0, Weight.GRAMS), "Paris"));
            parts.add(new Part("P3", "Screw", "Blue",
                      new Weight(17.0, Weight.GRAMS), "Rome"));
            parts.add(new Part("P4", "Screw", "Red",
                      new Weight(14.0, Weight.GRAMS), "London"));
            parts.add(new Part("P5", "Cam", "Blue",
                      new Weight(12.0, Weight.GRAMS), "Paris"));
            parts.add(new Part("P6", "Cog", "Red",
                      new Weight(19.0, Weight.GRAMS), "London"));
        }</tt></b>
    }

private void addShipments()
    {
<b class="userinput"><tt>        Set shipments = views.getShipmentSet();
        if (shipments.isEmpty())
        {
            System.out.println("Adding Shipments");
            shipments.add(new Shipment("P1", "S1", 300));
            shipments.add(new Shipment("P2", "S1", 200));
            shipments.add(new Shipment("P3", "S1", 400));
            shipments.add(new Shipment("P4", "S1", 200));
            shipments.add(new Shipment("P5", "S1", 100));
            shipments.add(new Shipment("P6", "S1", 100));
            shipments.add(new Shipment("P1", "S2", 300));
            shipments.add(new Shipment("P2", "S2", 400));
            shipments.add(new Shipment("P2", "S3", 200));
            shipments.add(new Shipment("P2", "S4", 200));
            shipments.add(new Shipment("P4", "S4", 300));
            shipments.add(new Shipment("P5", "S4", 400));
        }</tt></b>
    } </pre>
      <p>
    Instead of printing the key/value pairs by iterating over the
	<a href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/Map.html#entrySet" target="_top">Map.entrySet</a>
	
	as done in the prior example, this example
	iterates over the entities in the 
    <a href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/Map.html#values" target="_top">Map.values</a>
    
	collection.
</p>
      <a id="entity_printdatabase"></a>
      <pre class="programlisting">import java.util.Iterator;
import java.util.Set;
...
public class Sample
{
    ...
    private class PrintDatabase implements TransactionWorker
    {
        public void doWork()
            throws Exception
        {
<b class="userinput"><tt>            printValues("Parts",
                         views.getPartSet().iterator());
            printValues("Suppliers",
                         views.getSupplierSet().iterator());</tt></b>
            printValues("Suppliers for City Paris",
                         views.getSupplierByCityMap().duplicates(
                                            "Paris").iterator());
<b class="userinput"><tt>            printValues("Shipments",
                         views.getShipmentSet().iterator());</tt></b>
            printValues("Shipments for Part P1",
                         views.getShipmentByPartMap().duplicates(
                                            new PartKey("P1")).iterator());
            printValues("Shipments for Supplier S1",
                         views.getShipmentBySupplierMap().duplicates(
                                            new SupplierKey("S1")).iterator());
        }
    }
    ...
} </pre>
      <p>
    The output of the example program is shown below.
</p>
      <pre class="programlisting">Adding Suppliers
Adding Parts
Adding Shipments

--- Parts ---
Part: number=P1 name=Nut color=Red weight=[12.0 grams] city=London
Part: number=P2 name=Bolt color=Green weight=[17.0 grams] city=Paris
Part: number=P3 name=Screw color=Blue weight=[17.0 grams] city=Rome
Part: number=P4 name=Screw color=Red weight=[14.0 grams] city=London
Part: number=P5 name=Cam color=Blue weight=[12.0 grams] city=Paris
Part: number=P6 name=Cog color=Red weight=[19.0 grams] city=London

--- Suppliers ---
Supplier: number=S1 name=Smith status=20 city=London
Supplier: number=S2 name=Jones status=10 city=Paris
Supplier: number=S3 name=Blake status=30 city=Paris
Supplier: number=S4 name=Clark status=20 city=London
Supplier: number=S5 name=Adams status=30 city=Athens

--- Suppliers for City Paris ---
Supplier: number=S2 name=Jones status=10 city=Paris
Supplier: number=S3 name=Blake status=30 city=Paris

--- Shipments ---
Shipment: part=P1 supplier=S1 quantity=300
Shipment: part=P1 supplier=S2 quantity=300
Shipment: part=P2 supplier=S1 quantity=200
Shipment: part=P2 supplier=S2 quantity=400
Shipment: part=P2 supplier=S3 quantity=200
Shipment: part=P2 supplier=S4 quantity=200
Shipment: part=P3 supplier=S1 quantity=400
Shipment: part=P4 supplier=S1 quantity=200
Shipment: part=P4 supplier=S4 quantity=300
Shipment: part=P5 supplier=S1 quantity=100
Shipment: part=P5 supplier=S4 quantity=400
Shipment: part=P6 supplier=S1 quantity=100

--- Shipments for Part P1 ---
Shipment: part=P1 supplier=S1 quantity=300
Shipment: part=P1 supplier=S2 quantity=300

--- Shipments for Supplier S1 ---
Shipment: part=P1 supplier=S1 quantity=300
Shipment: part=P2 supplier=S1 quantity=200
Shipment: part=P3 supplier=S1 quantity=400
Shipment: part=P4 supplier=S1 quantity=200
Shipment: part=P5 supplier=S1 quantity=100
Shipment: part=P6 supplier=S1 quantity=100 </pre>
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