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		Retrieving Database Items
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		Retrieving Database Items
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		Retrieving Database Items
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      <p>
    Retrieving information from the database is accomplished via the
	standard Java collections API. In the example, the 
	<a href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/Set.html#iterator" target="_top">Set.iterator</a>
	
    method is used to iterate all 
	<a href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/Map.Entry.html" target="_top">Map.Entry</a>
	
	objects for each store. All standard Java methods for retrieving
	objects from a collection may be used with the DB Java Collections API.
</p>
      <p>
    The <tt class="methodname">PrintDatabase.doWork()</tt> method calls
    <tt class="methodname">printEntries()</tt>
	to print the map entries for each database store. It is called via
	the 
    <a href="../../java/com/sleepycat/collections/TransactionRunner.html" target="_top">TransactionRunner</a>
    
	class and was outlined in the previous section.
</p>
      <a id="cb_printdatabase"></a>
      <pre class="programlisting">import java.util.Iterator;
...
public class Sample
{
    ...
    private SampleViews views;
    ...
    private class PrintDatabase implements TransactionWorker
    {
        public void doWork()
            throws Exception
        {
<b class="userinput"><tt>            printEntries("Parts",
                          views.getPartEntrySet().iterator());
            printEntries("Suppliers",
                          views.getSupplierEntrySet().iterator());
            printEntries("Shipments",
                          views.getShipmentEntrySet().iterator());</tt></b>
        }
    }
    ...

<b class="userinput"><tt>    private void printEntries(String label, Iterator iterator)
    {
    }</tt></b>
    ...
} </pre>
      <p>
    The 
    <a href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/Set.html" target="_top">Set</a>
    
	of 
    <a href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/Map.Entry.html" target="_top">Map.Entry</a>
    
	objects for each store is obtained from the <tt class="classname">SampleViews</tt>
	object. This set can also be obtained by calling the 
	<a href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/Map.html#entrySet" target="_top">Map.entrySet</a>
	
	method of a stored map.
</p>
      <p>
    The <tt class="methodname">printEntries()</tt> prints the map entries for any stored
	map. The 
	<a href="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Object.html#toString" target="_top">Object.toString</a>
	
	method of each key and value is called to
	obtain a printable representation of each object.
</p>
      <a id="cb_printentries"></a>
      <pre class="programlisting">    private void printEntries(String label, Iterator iterator)
    {
<b class="userinput"><tt>        System.out.println("\n--- " + label + " ---");
        while (iterator.hasNext())
        {
            Map.Entry entry = (Map.Entry) iterator.next();
            System.out.println(entry.getKey().toString());
            System.out.println(entry.getValue().toString());
        }</tt></b>
    } </pre>
      <p>
    This is one of a small number of behavioral differences between
	standard Java collections and stored collections. For a complete
	list see 
    <a href="UsingStoredCollections.html">
        Using Stored Collections
    </a>.
</p>
      <p>
    The output of the example program is shown below.
</p>
      <pre class="programlisting">Adding Suppliers
Adding Parts
Adding Shipments

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

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

--- Shipments ---
ShipmentKey: supplier=S1 part=P1
ShipmentData: quantity=300
ShipmentKey: supplier=S2 part=P1
ShipmentData: quantity=300
ShipmentKey: supplier=S1 part=P2
ShipmentData: quantity=200
ShipmentKey: supplier=S2 part=P2
ShipmentData: quantity=400
ShipmentKey: supplier=S3 part=P2
ShipmentData: quantity=200
ShipmentKey: supplier=S4 part=P2
ShipmentData: quantity=200
ShipmentKey: supplier=S1 part=P3
ShipmentData: quantity=400
ShipmentKey: supplier=S1 part=P4
ShipmentData: quantity=200
ShipmentKey: supplier=S4 part=P4
ShipmentData: quantity=300
ShipmentKey: supplier=S1 part=P5
ShipmentData: quantity=100
ShipmentKey: supplier=S4 part=P5
ShipmentData: quantity=400
ShipmentKey: supplier=S1 part=P6
ShipmentData: quantity=100 </pre>
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