Home Accessibility Courses Twitter The Mouth Facebook Resources Site Map About Us Contact
 
For 2021 - online Python 3 training - see ((here)).

Our plans were to retire in summer 2020 and see the world, but Coronavirus has lead us into a lot of lockdown programming in Python 3 and PHP 7.
We can now offer tailored online training - small groups, real tutors - works really well for groups of 4 to 14 delegates. Anywhere in the world; course language English.

Please ask about private 'maintenance' training for Python 2, Tcl, Perl, PHP, Lua, etc.
Creating a hash of objects
Fundamental classes example from a Well House Consultants training course
More on Fundamental classes [link]

This example is described in the following article(s):
   • Java - factory method, encapsulation, hashmap example - [link]

Source code: AUtil.java Module: J714
/*
This example puts together various Java elements into a complete program to set up a table, keyed by a text string,
of objects. We've used a "Hashmap" from the Java Utility Package to hold our keys and the objects which we've
associated with each key - in this case railway station information keyed by the industry's internal three letter
code system. You'll note that there's no detail of what the data format of the incoming data file is in this
main application, as that minutiae is delegated down to the NetworkStation class, which will be written and
maitaineed by an expert in that particular data, and can be shared between a number of different applications all of
which need to access that data.
*/


import java.io.*;
import java.util.*;

public class AUtil{
public static void main(String [] args) throws IOException {

// We're going to read the incoming data file defined on the comment line, one line at a time

        BufferedReader Stuff = new BufferedReader(new FileReader(args[0]));

        String lyne;
        HashMap info = new HashMap();

// Loop through the incoming lines of data and pass each to a factory to return a NetworkStation object
        while ( (lyne = Stuff.readLine()) != null) {
                NetworkStation current = (NetworkStation)NetworkStation.Factory(lyne);
                // We've assumed that the factory always succeeds. May want to check for null return?
                String ThreeLetterCode = current.getCode();
                // add the object newly manufactured by the factory into the hash
                info.put(ThreeLetterCode,current);
        }

// For testing, output the object that has the key "LLS" as converted to a string

        System.out.println(info.get("LLS"));

// Iterate through the hash ... in other words output all the objects

        Set Places = info.keySet();
        Iterator Place = Places.iterator();

        while(Place.hasNext()) {
                String TLC = (String)Place.next();
                System.out.println(TLC);
                System.out.println(info.get(TLC));
        }

}}


Learn about this subject
This module and example are covered on the following public courses:
 * Learning to Program in Java
 * Java Bootcamp
 * Java Programming for the Web
Also available on on site courses for larger groups

Books covering this topic
Yes. We have over 700 books in our library. Books covering Java and associated technologies are listed here and when you've selected a relevant book we'll link you on to Amazon to order.

Other Examples
This example comes from our "Fundamental classes" training module. You'll find a description of the topic and some other closely related examples on the "Fundamental classes" module index page.

Full description of the source code
You can learn more about this example on the training courses listed on this page, on which you'll be given a full set of training notes.

Many other training modules are available for download (for limited use) from our download centre under an Open Training Notes License.

Other resources
• Our Solutions centre provides a number of longer technical articles.
• Our Opentalk forum archive provides a question and answer centre.
The Horse's mouth provides a daily tip or thought.
• Further resources are available via the resources centre.
• All of these resources can be searched through through our search engine
• And there's a global index here.

Purpose of this website
This is a sample program, class demonstration or answer from a training course. It's main purpose is to provide an after-course service to customers who have attended our public private or on site courses, but the examples are made generally available under conditions described below.

Web site author
This web site is written and maintained by Well House Consultants.

Conditions of use
Past attendees on our training courses are welcome to use individual examples in the course of their programming, but must check the examples they use to ensure that they are suitable for their job. Remember that some of our examples show you how not to do things - check in your notes. Well House Consultants take no responsibility for the suitability of these example programs to customer's needs.

This program is copyright Well House Consultants Ltd. You are forbidden from using it for running your own training courses without our prior written permission. See our page on courseware provision for more details.

Any of our images within this code may NOT be reused on a public URL without our prior permission. For Bona Fide personal use, we will often grant you permission provided that you provide a link back. Commercial use on a website will incur a license fee for each image used - details on request.

You can Add a comment or ranking to this page

© WELL HOUSE CONSULTANTS LTD., 2022: 48 Spa Road • Melksham, Wiltshire • United Kingdom • SN12 7NY
PH: 01144 1225 708225 • EMAIL: info@wellho.net • WEB: http://www.wellho.net • SKYPE: wellho

PAGE: http://www.wellho.net/resources/ex.php • PAGE BUILT: Sun Oct 11 14:50:09 2020 • BUILD SYSTEM: JelliaJamb