Mega Code Archive
Demonstrate the Hashtable class, and an Enumeration
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/*
* Copyright (c) Ian F. Darwin, http://www.darwinsys.com/, 1996-2002.
* All rights reserved. Software written by Ian F. Darwin and others.
* $Id: LICENSE,v 1.8 2004/02/09 03:33:38 ian Exp $
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS''
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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*
* Java, the Duke mascot, and all variants of Sun's Java "steaming coffee
* cup" logo are trademarks of Sun Microsystems. Sun's, and James Gosling's,
* pioneering role in inventing and promulgating (and standardizing) the Java
* language and environment is gratefully acknowledged.
*
* The pioneering role of Dennis Ritchie and Bjarne Stroustrup, of AT&T, for
* inventing predecessor languages C and C++ is also gratefully acknowledged.
*/
import java.util.Enumeration;
import java.util.Hashtable;
/**
* Demonstrate the Hashtable class, and an Enumeration.
*
* @see HashMapDemo, for the newer HashMap class.
*/
public class HashtableDemo {
public static void main(String[] argv) {
// Construct and load the hash. This simulates loading a
// database or reading from a file, or wherever the data is.
Hashtable h = new Hashtable();
// The hash maps from company name to address.
// In real life this might map to an Address object...
h.put("Adobe", "Mountain View, CA");
h.put("IBM", "White Plains, NY");
h.put("Learning Tree", "Los Angeles, CA");
h.put("Microsoft", "Redmond, WA");
h.put("Netscape", "Mountain View, CA");
h.put("O'Reilly", "Sebastopol, CA");
h.put("Sun", "Mountain View, CA");
// Two versions of the "retrieval" phase.
// Version 1: get one pair's value given its key
// (presumably the key would really come from user input):
String queryString = "O'Reilly";
System.out.println("You asked about " + queryString + ".");
String resultString = (String) h.get(queryString);
System.out.println("They are located in: " + resultString);
System.out.println();
// Version 2: get ALL the keys and pairs
// (maybe to print a report, or to save to disk)
Enumeration k = h.keys();
while (k.hasMoreElements()) {
String key = (String) k.nextElement();
System.out.println("Key " + key + "; Value " + (String) h.get(key));
}
}
}
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