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HTML
276 lines
9.7 KiB
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<?xml version="1.0" encoding="UTF-8" standalone="no"?>
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml">
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
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<title>Chapter 6. A DPL Example</title>
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<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
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<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
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<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
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<link rel="up" href="dpl.html" title="Part I. Programming with the Direct Persistence Layer" />
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<link rel="prev" href="dpl_replace.html" title="Replacing Entity Objects" />
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<link rel="next" href="inventoryclass.html" title="Inventory.java" />
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</head>
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<body>
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<div xmlns="" class="navheader">
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<div class="libver">
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<p>Library Version 12.2.7.5</p>
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</div>
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<table width="100%" summary="Navigation header">
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<tr>
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<th colspan="3" align="center">Chapter 6. A DPL Example</th>
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</tr>
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<tr>
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<td width="20%" align="left"><a accesskey="p" href="dpl_replace.html">Prev</a> </td>
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<th width="60%" align="center">Part I. Programming with the Direct Persistence Layer</th>
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<td width="20%" align="right"> <a accesskey="n" href="inventoryclass.html">Next</a></td>
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</tr>
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</table>
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<hr />
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</div>
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<div class="chapter" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h2 class="title"><a id="dpl_example"></a>Chapter 6. A DPL Example</h2>
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</div>
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</div>
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</div>
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<div class="toc">
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<p>
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<b>Table of Contents</b>
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</p>
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<dl>
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<dt>
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<span class="sect1">
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<a href="dpl_example.html#vendorclass">Vendor.java</a>
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</span>
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</dt>
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<dt>
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<span class="sect1">
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<a href="inventoryclass.html">Inventory.java</a>
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</span>
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</dt>
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<dt>
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<span class="sect1">
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<a href="mydbenv-persist.html">MyDbEnv</a>
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</span>
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</dt>
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<dt>
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<span class="sect1">
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<a href="dataaccessorclass.html">DataAccessor.java</a>
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</span>
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</dt>
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<dt>
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<span class="sect1">
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<a href="dpl_exampledatabaseput.html">ExampleDatabasePut.java</a>
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</span>
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</dt>
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<dt>
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<span class="sect1">
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<a href="dpl_exampleinventoryread.html">ExampleInventoryRead.java</a>
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</span>
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</dt>
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</dl>
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</div>
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<p>
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In order to illustrate DPL usage, we provide a
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complete working example in this chapter. This example
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reads and writes inventory and vendor information for a
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mythical business. The application consists of the
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following classes:
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</p>
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<div class="itemizedlist">
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<ul type="disc">
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<li>
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<p>
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Several classes used to encapsulate our
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application's data. See
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<a class="xref" href="dpl_example.html#vendorclass" title="Vendor.java">Vendor.java</a>
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and
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<a class="xref" href="inventoryclass.html" title="Inventory.java">Inventory.java</a>.
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</p>
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</li>
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<li>
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<p>
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A convenience class used to open and close
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our environment and entity store. See
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<a class="xref" href="mydbenv-persist.html" title="MyDbEnv">MyDbEnv</a>.
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</p>
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</li>
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<li>
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<p>
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A class that loads data into the store. See
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<a class="xref" href="dpl_exampledatabaseput.html" title="ExampleDatabasePut.java">ExampleDatabasePut.java</a>.
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</p>
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</li>
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<li>
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<p>
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Finally, a class that reads data from the
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store. See
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<a class="xref" href="dpl_exampleinventoryread.html" title="ExampleInventoryRead.java">ExampleInventoryRead.java</a>.
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</p>
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</li>
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</ul>
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</div>
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<p>
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Be aware that this example can be found in your JE distribution in
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the following location:
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</p>
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<p>
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<span class="emphasis"><em>JE_HOME</em></span>/examples/persist/gettingStarted
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</p>
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<p>
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where <code class="literal"><span class="emphasis"><em>JE_HOME</em></span></code> is the location where you
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placed your JE distribution.
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</p>
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<div class="sect1" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h2 class="title" style="clear: both"><a id="vendorclass"></a>Vendor.java</h2>
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</div>
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</div>
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</div>
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<p>
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The simplest class that our example wants to store contains
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vendor contact information. This class contains no
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secondary indices so all we have to do is identify it
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as an entity class and identify the field in the
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class used for the primary key.
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</p>
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<p>
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In the following example, we identify the
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<code class="literal">vendor</code> data member as containing the
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primary key. This data member is meant to contain a
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vendor's name. Because of the way we will use our
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<code class="classname">EntityStore</code>, the value
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provided for this data member must be unique within
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the store or runtime errors will result.
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</p>
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<p>
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When used with the DPL, our
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<code class="classname">Vendor</code> class appears as
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follows. Notice that the <code class="literal">@Entity</code>
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annotation appears immediately before the class
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declaration, and the <code class="literal">@PrimaryKey</code>
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annotation appears immediately before the
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<code class="literal">vendor</code> data member declaration.
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</p>
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<pre class="programlisting">package persist.gettingStarted;
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import com.sleepycat.persist.model.Entity;
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import com.sleepycat.persist.model.PrimaryKey;
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@Entity
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public class Vendor {
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private String address;
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private String bizPhoneNumber;
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private String city;
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private String repName;
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private String repPhoneNumber;
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private String state;
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// Primary key is the vendor's name
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// This assumes that the vendor's name is
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// unique in the database.
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@PrimaryKey
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private String vendor;
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private String zipcode;
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public void setRepName(String data) {
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repName = data;
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}
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public void setAddress(String data) {
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address = data;
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}
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public void setCity(String data) {
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city = data;
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}
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public void setState(String data) {
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state = data;
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}
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public void setZipcode(String data) {
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zipcode = data;
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}
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public void setBusinessPhoneNumber(String data) {
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bizPhoneNumber = data;
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}
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public void setRepPhoneNumber(String data) {
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repPhoneNumber = data;
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}
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public void setVendorName(String data) {
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vendor = data;
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}
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public String getRepName() {
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return repName;
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}
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public String getAddress() {
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return address;
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}
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public String getCity() {
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return city;
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}
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public String getState() {
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return state;
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}
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public String getZipcode() {
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return zipcode;
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}
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public String getBusinessPhoneNumber() {
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return bizPhoneNumber;
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}
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public String getRepPhoneNumber() {
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return repPhoneNumber;
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}
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} </pre>
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<p>
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For this class, the <code class="literal">vendor</code> value is set for an individual
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<code class="classname">Vendor</code> class object by
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the <code class="methodname">setVendorName()</code>
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method. If our example code fails to set this
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value before storing the object, the data
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member used to store the primary key is set to a
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null value. This would result in a runtime
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error.
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</p>
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</div>
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</div>
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<div class="navfooter">
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<hr />
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<table width="100%" summary="Navigation footer">
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|||
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<tr>
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|||
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<td width="40%" align="left"><a accesskey="p" href="dpl_replace.html">Prev</a> </td>
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|||
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<td width="20%" align="center">
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|||
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<a accesskey="u" href="dpl.html">Up</a>
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|||
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</td>
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|||
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<td width="40%" align="right"> <a accesskey="n" href="inventoryclass.html">Next</a></td>
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|||
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</tr>
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<tr>
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|||
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<td width="40%" align="left" valign="top">Replacing Entity Objects </td>
|
|||
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<td width="20%" align="center">
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|||
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<a accesskey="h" href="index.html">Home</a>
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|||
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</td>
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<td width="40%" align="right" valign="top"> Inventory.java</td>
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</tr>
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</table>
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</div>
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</body>
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</html>
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