Utility classes ArrayList and Hashmap set up to help analyse data file

Fundamental classes example from a Well House Consultants training course
More on Fundamental classes [link]

This example is described in the following article(s):
• String handling - from first steps to practical examples - [link]

Source code: Tshirt.java Module: J714

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

/* Read data from a server log file and count the number of
accesses to lines containing a certain word "Swindon". Use
the ArrayList and HashMap utility classes to get a list of
the IP addresses, and a table of the IP addresses with a
note of how many times each has been used. */

public class Tshirt {

        public static void main (String [] args)
                                throws FileNotFoundException, IOException {

                int countplace = 0, countlines = 0;
                int iptop; String RemoteIp;
                BufferedReader Suck = new BufferedReader(new FileReader(args[0]));
                String Stuff;

                // Read and store all Swindon interest by IP

                ArrayList<String> Iprecords = new ArrayList<String>();

                // Also store a count of visits from each different IP

                HashMap Counters = new HashMap();

                while ((Stuff = Suck.readLine()) != null) {
                        countlines ++;
                        iptop = Stuff.indexOf(" ");
                        RemoteIp = Stuff.substring(0,iptop);
                        if (Stuff.indexOf("Swindon") >= 0) {

                                        // Store onto an ArrayList

                                        Iprecords.add(RemoteIp);

                                        // Also store into a HashMap

                                        // Get count so far for this IP from Hashmap
                                        Integer temp = (Integer)Counters.get(RemoteIp);
                                        // If this is an IP we have not seen before, set 0
                                        if (temp == null) temp = new Integer(0);
                                        // Store one more than previous value into Hashmap
                                        Integer newval = new Integer(1+temp.intValue());
                                        Counters.put(RemoteIp,newval);

                                        countplace++;

                        }
                }

                System.out.println("Total " + countlines);
                System.out.println("Matched " + countplace);

                // And print out IP list too

                for (int k=0; k<Iprecords.size(); k++) {
                        String iprecalled = Iprecords.get(k);
                        System.out.println(iprecalled);
                }

                System.out.println("----------------");

                // Print out IP list with times each occurred from the HashMap

                // Get the keys so that we can handle them each in turn [keyset]
                Set HostKeys = Counters.keySet();
                // Make an iterator which can step through the keyset one by one
                Iterator It = HostKeys.iterator();

                // "while we still have data available from the iterator ..."
                while (It.hasNext()) {
                        // " ... get the next piece of data [key]"
                        String HostNow = (String)(It.next());
                        int c = ((Integer)Counters.get(HostNow)).intValue();

                        // Print out the IP addresses and the counts alongside
                        System.out.println((String)HostNow + " - " + c);
                }
        }
}

/* Sample output -

wizard:jn10 graham$ java Tshirt ac_20101105
Total 134652
Matched 49
207.46.195.225
67.195.112.232
67.195.112.232
66.249.65.122
207.46.195.234
66.249.65.122
208.115.111.250
209.51.162.220
207.46.13.98
207.46.195.230
95.150.152.116
195.246.108.11
195.246.108.11
195.246.108.11
195.246.108.11
207.46.13.44
195.246.108.11
207.46.204.222
207.46.204.222
66.249.66.134
66.249.66.134
66.249.66.134
67.195.115.231
66.249.66.59
77.88.27.25
66.249.66.119
66.249.66.130
66.249.66.130
66.249.66.130
66.249.66.130
66.249.66.130
66.249.66.130
66.249.66.130
66.249.66.130
66.249.66.130
66.249.66.130
66.235.124.57
207.46.204.233
66.249.66.119
66.249.66.119
67.195.112.232
66.249.66.119
79.142.66.55
220.181.94.224
217.160.182.81
217.160.182.81
217.160.182.81
217.160.182.81
66.249.66.119
----------------
66.249.66.130 - 10
95.150.152.116 - 1
66.249.66.59 - 1
207.46.204.222 - 2
195.246.108.11 - 5
207.46.204.233 - 1
220.181.94.224 - 1
209.51.162.220 - 1
77.88.27.25 - 1
207.46.13.98 - 1
66.249.66.134 - 3
217.160.182.81 - 4
66.235.124.57 - 1
67.195.115.231 - 1
207.46.195.230 - 1
207.46.195.225 - 1
67.195.112.232 - 3
207.46.13.44 - 1
66.249.65.122 - 2
208.115.111.250 - 1
79.142.66.55 - 1
66.249.66.119 - 5
207.46.195.234 - 1
wizard:jn10 graham$

*/

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.

Web site author

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

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.

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.