<!--$Id: read.so,v 1.3 2003/09/03 18:34:46 gburd Exp $-->
<!--Copyright 1997-2003 by Sleepycat Software, Inc.-->
<!--All rights reserved.-->
<!--See the file LICENSE for redistribution information.-->
<html>
<head>
<title>Berkeley DB Reference Guide: Using entities with collections</title>
<meta name="description" content="Berkeley DB: An embedded database programmatic toolkit.">
<meta name="keywords" content="embedded,database,programmatic,toolkit,b+tree,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,Java,C,C++">
</head>
<body bgcolor=white>
<a name="2"><!--meow--></a>
<table width="100%"><tr valign=top>
<td><h3><dl><dt>Berkeley DB Reference Guide:<dd>Java API Tutorial - Entity</dl></h3></td>
<td align=right><a href="../bdb_entity/views.html"><img src="../../images/prev.gif" alt="Prev"></a><a href="../toc.html"><img src="../../images/ref.gif" alt="Ref"></a><a href="../bdb_tuple/intro.html"><img src="../../images/next.gif" alt="Next"></a>
</td></tr></table>
<p>
<h3 align=center>Using entities with collections</h3>
<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/1.3/docs/api/java/util/Map.html#values">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>
<hr size=1 noshade>
<p>The <b>Sample</b> class has been changed in this example to add
objects using the
<a href="http://java.sun.com/j2se/1.3/docs/api/java/util/Set.html#add">Set.add</a>
method rather than the
<a href="http://java.sun.com/j2se/1.3/docs/api/java/util/Map.html#put">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/1.3/docs/api/java/util/Set.html#add">Set.add</a>
.</p>
<blockquote><pre>
public class Sample
{
...
private void addSuppliers()
{
<b> 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"));
}
</b> }
<p>
private void addParts()
{
<b> 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"));
}
</b> }
<p>
private void addShipments()
{
<b> 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));
}
</b> }
</pre></blockquote>
<hr size=1 noshade>
<p>Instead of printing the key/value pairs by iterating over the
<a href="http://java.sun.com/j2se/1.3/docs/api/java/util/Map.html#entrySet">Map.entrySet</a>
as done in the prior example, this
example iterates over the entities in the
<a href="http://java.sun.com/j2se/1.3/docs/api/java/util/Map.html#values">Map.values</a>
collection.</p>
<blockquote><pre>
import com.sleepycat.bdb.collection.StoredIterator;
import java.util.Iterator;
import java.util.Set;
...
public class Sample
{
...
private class PrintDatabase implements TransactionWorker
{
public void doWork()
throws Exception
{
<b> printValues("Parts",
views.getPartSet().iterator());
printValues("Suppliers",
views.getSupplierSet().iterator());
</b> printValues("Suppliers for City Paris",
views.getSupplierByCityMap().duplicates(
"Paris").iterator());
<b> printValues("Shipments",
views.getShipmentSet().iterator());
</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></blockquote>
<hr size=1 noshade>
<p>The output of the example program is shown below.</p>
<blockquote><pre>
Adding Suppliers
Adding Parts
Adding Shipments
<p>
--- 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
<p>
--- 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
<p>
--- Suppliers for City Paris ---
Supplier: number=S2 name=Jones status=10 city=Paris
Supplier: number=S3 name=Blake status=30 city=Paris
<p>
--- 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
<p>
--- Shipments for Part P1 ---
Shipment: part=P1 supplier=S1 quantity=300
Shipment: part=P1 supplier=S2 quantity=300
<p>
--- 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></blockquote>
<table width="100%"><tr><td><br></td><td align=right><a href="../bdb_entity/views.html"><img src="../../images/prev.gif" alt="Prev"></a><a href="../toc.html"><img src="../../images/ref.gif" alt="Ref"></a><a href="../bdb_tuple/intro.html"><img src="../../images/next.gif" alt="Next"></a>
</td></tr></table>
<p><font size=1><a href="../../sleepycat/legal.html">Copyright (c) 1996-2003</a> <a href="http://www.sleepycat.com">Sleepycat Software, Inc.</a> - All rights reserved.</font>
</body>
</html>
distrib
>
Mandriva
>
2007.0
>
x86_64
>
media
>
main-release
>
by-pkgid
>
a4c98df40e78f6c892308fd6841f950a
>
files
>
844
