<?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 V1.73.2" /> <link rel="start" href="index.html" title="Berkeley DB Collections Tutorial" /> <link rel="up" href="Entity.html" title="Chapter 4. Using Entity Classes" /> <link rel="prev" href="collectionswithentities.html" title="Creating Collections with Entity Bindings" /> <link rel="next" href="Tuple.html" title="Chapter 5. Using Tuples" /> </head> <body> <div xmlns="" class="navheader"> <div class="libver"> <p>Library Version 12.1.6.1</p> </div> <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> <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 class="ulink" href="http://download.oracle.com/javase/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 <code class="classname">Sample</code> class has been changed in this example to add objects using the <a class="ulink" href="http://download.oracle.com/javase/1.5.0/docs/api/java/util/Set.html#add(E)" target="_top">Set.add</a> method rather than the <a class="ulink" href="http://download.oracle.com/javase/1.5.0/docs/api/java/util/Map.html#put(K, V)" target="_top">Map.put</a> method that was used in the prior examples. Entity objects are constructed and passed to <a class="ulink" href="http://download.oracle.com/javase/1.5.0/docs/api/java/util/Set.html#add(E)" target="_top">Set.add</a>. </p> <a id="entity_addsuppliers"></a> <pre class="programlisting">import java.util.Set; ... public class Sample { ... private void addSuppliers() { <strong class="userinput"><code> 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")); }</code></strong> } private void addParts() { <strong class="userinput"><code> 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")); }</code></strong> } private void addShipments() { <strong class="userinput"><code> 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)); }</code></strong> } </pre> <p> Instead of printing the key/value pairs by iterating over the <a class="ulink" href="http://download.oracle.com/javase/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 class="ulink" href="http://download.oracle.com/javase/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 { <strong class="userinput"><code> printValues("Parts", views.getPartSet().iterator()); printValues("Suppliers", views.getSupplierSet().iterator());</code></strong> printValues("Suppliers for City Paris", views.getSupplierByCityMap().duplicates( "Paris").iterator()); <strong class="userinput"><code> printValues("Shipments", views.getShipmentSet().iterator());</code></strong> 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. 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