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272 lines
11 KiB
HTML
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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>ExampleInventoryRead.java</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_example.html" title="Chapter 6. A DPL Example" />
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<link rel="prev" href="dpl_exampledatabaseput.html" title="ExampleDatabasePut.java" />
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<link rel="next" href="baseapi.html" title="Part II. Programming with the Base API" />
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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">ExampleInventoryRead.java</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_exampledatabaseput.html">Prev</a> </td>
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<th width="60%" align="center">Chapter 6. A DPL Example</th>
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<td width="20%" align="right"> <a accesskey="n" href="baseapi.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="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="dpl_exampleinventoryread"></a>ExampleInventoryRead.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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<code class="classname">ExampleInventoryRead</code>
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retrieves
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inventory information from our entity store and
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displays it. When it displays each inventory item, it
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also displays the related vendor contact information.
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</p>
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<p>
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<code class="classname">ExampleInventoryRead</code>
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can do one of two things. If you provide no search
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criteria, it displays all of the inventory items in the
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store. If you provide an item name (using the
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<code class="literal">-s</code> command line switch), then just
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those inventory items using that name are displayed.
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</p>
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<p>
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The beginning of our example is almost identical to our
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<code class="classname">ExampleDatabasePut</code>
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example program. We
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repeat that example code here for the sake of
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completeness. For a complete walk-through of it, see
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the previous section (<a class="xref" href="dpl_exampledatabaseput.html" title="ExampleDatabasePut.java">ExampleDatabasePut.java</a>).
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</p>
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<pre class="programlisting">package persist.gettingStarted;
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import java.io.File;
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import java.io.IOException;
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import com.sleepycat.je.DatabaseException;
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import com.sleepycat.persist.EntityCursor;
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public class ExampleInventoryRead {
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private static File myDbEnvPath =
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new File("/tmp/JEDB");
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private DataAccessor da;
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// Encapsulates the database environment.
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private static MyDbEnv myDbEnv = new MyDbEnv();
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// The item to locate if the -s switch is used
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private static String locateItem;
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private static void usage() {
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System.out.println("ExampleInventoryRead [-h <env directory>]" +
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"[-s <item to locate>]");
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System.exit(-1);
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}
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public static void main(String args[]) {
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ExampleInventoryRead eir = new ExampleInventoryRead();
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try {
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eir.run(args);
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} catch (DatabaseException dbe) {
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System.err.println("ExampleInventoryRead: " + dbe.toString());
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dbe.printStackTrace();
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} finally {
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myDbEnv.close();
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}
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System.out.println("All done.");
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}
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private void run(String args[])
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throws DatabaseException {
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// Parse the arguments list
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parseArgs(args);
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myDbEnv.setup(myDbEnvPath, // path to the environment home
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true); // is this environment read-only?
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// Open the data accessor. This is used to retrieve
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// persistent objects.
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da = new DataAccessor(myDbEnv.getEntityStore());
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// If a item to locate is provided on the command line,
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// show just the inventory items using the provided name.
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// Otherwise, show everything in the inventory.
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if (locateItem != null) {
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showItem();
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} else {
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showAllInventory();
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}
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} </pre>
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<p>
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The first method that we provide is used to show inventory
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items related to a given inventory name. This method is called
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only if an inventory name is passed to
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<code class="classname">ExampleInventoryRead</code>
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via the <code class="literal">-s</code> option. Given the sample data
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that we provide with this example, each matching inventory name
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will result in the display of three inventory objects.
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</p>
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<p>
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To display these objects we use the
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<code class="classname">Inventory</code> class'
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<code class="literal">inventoryByName</code> secondary index to retrieve
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an <code class="classname">EntityCursor</code>, and then we iterate
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over the resulting objects using the cursor.
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</p>
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<p>
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Notice that this method calls
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<code class="methodname">displayInventoryRecord()</code>
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to display each individual object. We show this
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method a little later in the example.
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</p>
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<pre class="programlisting"> // Shows all the inventory items that exist for a given
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// inventory name.
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private void showItem() throws DatabaseException {
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// Use the inventory name secondary key to retrieve
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// these objects.
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EntityCursor<Inventory> items =
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da.inventoryByName.subIndex(locateItem).entities();
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try {
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for (Inventory item : items) {
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displayInventoryRecord(item);
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}
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} finally {
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items.close();
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}
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} </pre>
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<p>
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Next we implement <code class="methodname">showAllInventory()</code>,
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which shows all of the <code class="classname">Inventory</code>
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objects in the store. To do this, we
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obtain an <code class="classname">EntityCursor</code>
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from the <code class="classname">Inventory</code> class'
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primary index and, again, we iterate using that cursor.
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</p>
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<pre class="programlisting"> // Displays all the inventory items in the store
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private void showAllInventory()
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throws DatabaseException {
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// Get a cursor that will walk every
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// inventory object in the store.
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EntityCursor<Inventory> items =
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da.inventoryBySku.entities();
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try {
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for (Inventory item : items) {
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displayInventoryRecord(item);
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}
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} finally {
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items.close();
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}
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} </pre>
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<p>
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Now we implement
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<code class="methodname">displayInventoryRecord()</code>. This
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uses the getter methods on the <code class="classname">Inventory</code>
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class to obtain the information that we want to display.
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The only thing interesting about this method is that we
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obtain <code class="classname">Vendor</code> objects within.
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The vendor objects are retrieved <code class="classname">Vendor</code>
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objects using their primary index. We get the key
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for the retrieval from the <code class="classname">Inventory</code>
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object that we are displaying at the time.
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</p>
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<pre class="programlisting"> private void displayInventoryRecord(Inventory theInventory)
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throws DatabaseException {
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System.out.println(theInventory.getSku() + ":");
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System.out.println("\t " + theInventory.getItemName());
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System.out.println("\t " + theInventory.getCategory());
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System.out.println("\t " + theInventory.getVendor());
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System.out.println("\t\tNumber in stock: " +
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theInventory.getVendorInventory());
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System.out.println("\t\tPrice per unit: " +
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theInventory.getVendorPrice());
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System.out.println("\t\tContact: ");
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Vendor theVendor =
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da.vendorByName.get(theInventory.getVendor());
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assert theVendor != null;
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System.out.println("\t\t " + theVendor.getAddress());
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System.out.println("\t\t " + theVendor.getCity() + ", " +
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theVendor.getState() + " " + theVendor.getZipcode());
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System.out.println("\t\t Business Phone: " +
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theVendor.getBusinessPhoneNumber());
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System.out.println("\t\t Sales Rep: " +
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theVendor.getRepName());
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System.out.println("\t\t " +
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theVendor.getRepPhoneNumber());
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} </pre>
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<p>
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The last remaining parts of the example are used to parse
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the command line. This is not very
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interesting for our purposes here, but we show it anyway
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for the sake of completeness.
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</p>
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<pre class="programlisting"> protected ExampleInventoryRead() {}
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private static void parseArgs(String args[]) {
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for(int i = 0; i < args.length; ++i) {
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if (args[i].startsWith("-")) {
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switch(args[i].charAt(1)) {
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case 'h':
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myDbEnvPath = new File(args[++i]);
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break;
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case 's':
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locateItem = args[++i];
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break;
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default:
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usage();
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}
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}
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}
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}
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} </pre>
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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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<tr>
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<td width="40%" align="left"><a accesskey="p" href="dpl_exampledatabaseput.html">Prev</a> </td>
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<td width="20%" align="center">
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<a accesskey="u" href="dpl_example.html">Up</a>
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</td>
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<td width="40%" align="right"> <a accesskey="n" href="baseapi.html">Next</a></td>
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</tr>
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<tr>
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<td width="40%" align="left" valign="top">ExampleDatabasePut.java </td>
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<td width="20%" align="center">
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<a accesskey="h" href="index.html">Home</a>
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</td>
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<td width="40%" align="right" valign="top"> Part II. Programming with the Base API</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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