196 lines
10 KiB
HTML
196 lines
10 KiB
HTML
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<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE html
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PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html lang="en-us" xml:lang="en-us">
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
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<meta name="security" content="public" />
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<meta http-equiv="PICS-Label" content='(PICS-1.1 "http://www.icra.org/ratingsv02.html" l gen true r (cz 1 lz 1 nz 1 oz 1 vz 1) "http://www.rsac.org/ratingsv01.html" l gen true r (n 0 s 0 v 0 l 0) "http://www.classify.org/safesurf/" l gen true r (SS~~000 1))' />
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<meta name="DC.Type" content="reference" />
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<meta name="DC.Title" content="KeyedFile" />
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<meta name="abstract" content="" />
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<meta name="description" content="" />
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<meta name="copyright" content="(C) Copyright IBM Corporation 2006" />
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<meta name="DC.Rights.Owner" content="(C) Copyright IBM Corporation 2006" />
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<meta name="DC.Format" content="XHTML" />
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<meta name="DC.Identifier" content="rlakey" />
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<meta name="DC.Language" content="en-us" />
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<!-- All rights reserved. Licensed Materials Property of IBM -->
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<!-- US Government Users Restricted Rights -->
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<!-- Use, duplication or disclosure restricted by -->
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<!-- GSA ADP Schedule Contract with IBM Corp. -->
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<link rel="stylesheet" type="text/css" href="./ibmdita.css" />
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<link rel="stylesheet" type="text/css" href="./ic.css" />
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<title>KeyedFile</title>
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</head>
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<body id="rlakey"><a name="rlakey"><!-- --></a>
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<!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
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<h1 class="topictitle1">KeyedFile</h1>
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<div><p></p>
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<div class="section"><p>The <a href="javadoc/com/ibm/as400/access/KeyedFile.html#NAVBAR_TOP">KeyedFile</a> class gives a Java™ program keyed access to a file on the
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server. Keyed access means that the Java program can access the records of a
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file by specifying a key. Methods exist to position the cursor, read, update,
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and delete records by key.</p>
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</div>
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<div class="section"><p>To position the cursor, use the following methods:</p>
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</div>
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<div class="section"><ul><li><a href="javadoc/com/ibm/as400/access/KeyedFile.html#POSITIONCURSOR(BYTE[], INT)">positionCursor(Object[])</a> - set cursor to the first record
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with the specified key.</li>
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<li><a href="javadoc/com/ibm/as400/access/KeyedFile.html#POSITIONCURSORAFTER(BYTE[], INT)">positionCursorAfter(Object[])</a> - set cursor to the record
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after the first record with the specified key.</li>
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<li><a href="javadoc/com/ibm/as400/access/KeyedFile.html#POSITIONCURSORBEFORE(BYTE[], INT)">positionCursorBefore(Object[])</a> - set cursor to the record
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before the first record with the specified key.</li>
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</ul>
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</div>
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<div class="section"><p>To delete a record, use the following method :</p>
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</div>
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<div class="section"><ul><li><a href="javadoc/com/ibm/as400/access/KeyedFile.html#DELETERECORD(BYTE[], INT)">deleteRecord(Object[])</a> - delete the first record with
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the specified key.</li>
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</ul>
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</div>
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<div class="section"><p>The read methods are:</p>
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</div>
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<div class="section"><ul><li><a href="javadoc/com/ibm/as400/access/KeyedFile.html#READ(JAVA.LANG.OBJECT[])">read(Object[])</a> - read the first record with the specified
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key.</li>
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<li><a href="javadoc/com/ibm/as400/access/KeyedFile.html#READAFTER(BYTE[], INT)">readAfter(Object[])</a> - read the record after the first
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record with the specified key.</li>
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<li><a href="javadoc/com/ibm/as400/access/KeyedFile.html#READBEFORE(BYTE[], INT)">readBefore(Object[])</a> - read the record before the first
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record with the specified key.</li>
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<li><a href="javadoc/com/ibm/as400/access/KeyedFile.html#READNEXTEQUAL(BYTE[], INT)">readNextEqual()</a> - read the next record whose key matches
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the specified key. Searching starts from the record after the current cursor
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position.</li>
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<li><a href="javadoc/com/ibm/as400/access/KeyedFile.html#READPREVIOUSEQUAL(BYTE[], INT)">readPreviousEqual()</a> - read the previous record whose
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key matches the specified key. Searching starts from the record before the
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current cursor position.</li>
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</ul>
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</div>
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<div class="section"><p>To update a record, use the following method:</p>
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</div>
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<div class="section"><ul><li><a href="javadoc/com/ibm/as400/access/KeyedFile.html#UPDATE(BYTE[], COM.IBM.AS400.ACCESS.RECORD, INT)">update(Object[])</a> - update the record with the specified
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key.</li>
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</ul>
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</div>
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<div class="section"><p>Methods are also provided for specifying a search criteria when
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positioning, reading, and updating by key. Valid search criteria values are
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as follows:</p>
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</div>
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<div class="section"><ul><li><a href="javadoc/com/ibm/as400/access/KeyedFile.html#KEY_EQ">Equal</a> - find the first record whose key matches the
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specified key.</li>
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<li><a href="javadoc/com/ibm/as400/access/KeyedFile.html#KEY_LT">Less than</a> - find the last record whose key comes before
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the specified key in the key order of the file.</li>
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<li><a href="javadoc/com/ibm/as400/access/KeyedFile.html#KEY_LE">Less than or equal</a> - find the first record whose key
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matches the specified key. If no record matches the specified key, find the
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last record whose key comes before the specified key in the key order of the
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file.</li>
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<li><a href="javadoc/com/ibm/as400/access/KeyedFile.html#KEY_GT">Greater than</a> - find the first record whose key comes
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after the specified key in the key order of the file.</li>
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<li><a href="javadoc/com/ibm/as400/access/KeyedFile.html#KEY_GE">Greater than or equal</a> - find the first record whose key
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matches the specified key. If no record matches the specified key, find the
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first record whose key comes after the specified key in the key order of the
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file.</li>
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</ul>
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</div>
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<div class="section"><p>KeyedFile is a subclass of AS400File; all methods in AS400File
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are available to KeyedFile. </p>
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</div>
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<div class="section"><p><strong><span class="synph" id="rlakey__keyspec"><a name="rlakey__keyspec"><!-- --></a><span class="kwd"></span></span>Specifying the key</strong></p>
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</div>
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<div class="section"><p>The key for a KeyedFile object is represented by an array of Java Objects
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whose types and order correspond to the types and order of the key fields
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as specified by the <a href="javadoc/com/ibm/as400/access/RecordFormat.html">RecordFormat</a> object for the file.</p>
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</div>
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<div class="section"><p>The following example shows how to specify the key for the KeyedFile
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object.</p>
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</div>
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<div class="section"><div class="p"><pre> // Specify the key for a file whose key fields, in order,
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// are:
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// CUSTNAME CHAR(10)
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// CUSTNUM BINARY(9)
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// CUSTADDR CHAR(100)VARLEN()
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// Note that the last field is a variable-length field.
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Object[] theKey = new Object[3];
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theKey[0] = "John Doe";
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theKey[1] = new Integer(445123);
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theKey[2] = "2227 John Doe Lane, ANYTOWN, NY 11199"; </pre>
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</div>
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</div>
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<div class="section"><p>A KeyedFile object accepts partial keys as well as complete keys.
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However, the key field values that are specified must be in order.</p>
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</div>
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<div class="section"><p>For example:</p>
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</div>
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<div class="section"><div class="p"><pre> // Specify a partial key for a file whose key fields,
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// in order, are:
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// CUSTNAME CHAR(10)
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// CUSTNUM BINARY(9)
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// CUSTADDR CHAR(100)VARLEN()
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Object[] partialKey = new Object[2];
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partialKey[0] = "John Doe";
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partialKey[1] = new Integer(445123);
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// Example of an INVALID partial key
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Object[] INVALIDPartialKey = new Object[2];
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INVALIDPartialKey[0] = new Integer(445123);
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INVALIDPartialKey[1] = "2227 John Doe Lane, ANYTOWN, NY 11199";</pre>
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</div>
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<p>Null keys and null key fields are not supported.</p>
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<p>The
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key field values for a record can be obtained from the <a href="javadoc/com/ibm/as400/access/Record.html">Record</a> object
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for a file through the <a href="javadoc/com/ibm/as400/access/Record.html#GETKEYFIELDS()"> getKeyFields()</a> method.</p>
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<p>The following example shows
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how to read from a file by key:</p>
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<div class="p"><pre> // Create an AS400 object, the file exists on this
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// server.
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AS400 sys = new AS400("mySystem.myCompany.com");
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// Create a file object that represents the file
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KeyedFile myFile = new KeyedFile(sys, "/QSYS.LIB/MYLIB.LIB/MYFILE.FILE/%FILE%.MBR");
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// Assume that the AS400FileRecordDescription class
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// was used to generate the code for a subclass of
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// RecordFormat that represents the record format
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// of file MYFILE in library MYLIB. The code was
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// compiled and is available for use by the Java program.
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RecordFormat recordFormat = new MYKEYEDFILEFormat();
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// Set the record format for myFile. This must
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// be done before invoking open()
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myFile.setRecordFormat(recordFormat);
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// Open the file.
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myFile.open(AS400File.READ_WRITE, 0, AS400File.COMMIT_LOCK_LEVEL_NONE);
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// The record format for the file contains
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// four key fields, CUSTNUM, CUSTNAME, PARTNUM
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// and ORDNUM in that order.
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// The partialKey will contain 2 key field
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// values. Because the key field values must be
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// in order, the partialKey will consist of values for
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// CUSTNUM and CUSTNAME.
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Object[] partialKey = new Object[2];
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partialKey[0] = new Integer(1);
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partialKey[1] = "John Doe";
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// Read the first record matching partialKey
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Record keyedRecord = myFile.read(partialKey);
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// If the record was not found, null is returned.
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if (keyedRecord != null)
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{ // Found the record for John Doe, print out the info.
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System.out.println("Information for customer " + (String)partialKey[1] + ":");
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System.out.println(keyedRecord);
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}
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....
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// Close the file since I am done using it
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myFile.close();
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// Disconnect since I am done using record-level access
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sys.disconnectService(AS400.RECORDACCESS);</pre>
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</div>
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</div>
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</div>
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</body>
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</html>
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