PAL.C.T MINI SHELL
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<title>
Using Entities with Collections
</title>
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
<meta name="generator" content="DocBook XSL Stylesheets V1.62.4" />
<link rel="home" href="index.html" title="Berkeley DB Collections Tutorial" />
<link rel="up" href="Entity.html" title="Chapter 4. Using Entity Classes	 	" />
<link rel="previous" href="collectionswithentities.html" title=" 		Creating Collections with Entity Bindings 	" />
<link rel="next" href="Tuple.html" title="Chapter 5. 		Using Tuples 	" />
</head>
<body>
<div class="navheader">
<table width="100%" summary="Navigation header">
<tr>
<th colspan="3" align="center">
Using Entities with Collections
</th>
</tr>
<tr>
<td width="20%" align="left"><a accesskey="p" href="collectionswithentities.html">Prev</a> </td>
<th width="60%" align="center">Chapter 4.
Using Entity Classes
</th>
<td width="20%" align="right"> <a accesskey="n" href="Tuple.html">Next</a></td>
</tr>
</table>
<hr />
</div>
<div class="sect1" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h2 class="title" style="clear: both"><a id="entitieswithcollections"></a>
Using Entities with Collections
</h2>
</div>
</div>
<div></div>
</div>
<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>
</div>
<div class="navfooter">
<hr />
<table width="100%" summary="Navigation footer">
<tr>
<td width="40%" align="left"><a accesskey="p" href="collectionswithentities.html">Prev</a> </td>
<td width="20%" align="center">
<a accesskey="u" href="Entity.html">Up</a>
</td>
<td width="40%" align="right"> <a accesskey="n" href="Tuple.html">Next</a></td>
</tr>
<tr>
<td width="40%" align="left" valign="top">
Creating Collections with Entity Bindings
</td>
<td width="20%" align="center">
<a accesskey="h" href="index.html">Home</a>
</td>
<td width="40%" align="right" valign="top"> Chapter 5.
Using Tuples
</td>
</tr>
</table>
</div>
</body>
</html>
y~or5J ={Eeu磝Qk ᯘG{?+]ן?wM3X^歌>{7پK>on\jy R g/=fOroNVv~Y+ NGuÝHWyw[eQʨSb> >}Gmx[o[<{Ϯ_qF vM IENDB`