Home > Articles > Web Services > XML

  • Print
  • + Share This
This chapter is from the book


By far the hardest part of this or any similar problem is parsing the non-XML input data. Everything else pales by comparison. Unlike parsing XML, you generally cannot rely on a library to do the hard work for you. You have to do it yourself. And also unlike XML, there's little guarantee that the data is well-formed. More likely than not, you will encounter incorrectly formatted data.

In this case, because the records are separated into lines, I'll read each line, one at a time, using the readLine() method of java.io.BufferedReader. This method works well enough as long as the data is in a file, although it's potentially buggy when the data is served over a network socket.

Each line is dissected into its component fields inside the splitLine() method. Each record is stored in its own map. The keys for the map are read from a constant array, because the fields are always in the same position in each record.


For parsing the data out of each line, a lot of Java developers immediately reach for the java.util.StringTokenizer or java.io.StreamTokenizer classes. Don't. These classes are very strangely designed and rarely do what developers expect them to do. For example, if StreamTokenizer encounters a \n inside a string literal, it will convert it to a linefeed. This makes sense when parsing Java source code, but in most other environments \n is just another two characters with no special meaning. Java's tokenizer classes are designed for and suited to parsing Java source code. They are not suitable for reading tab- or comma-delimited data. If you want to design your program around a tokenization function, you should write one yourself that behaves appropriately for your data format.

Example 4.1 shows the input code. To use this, open an input stream to the file containing the budget data and pass that stream as an argument to the parse() method. You'll get back a List containing the parsed data. Each object in this list is a Map containing the data for one line item. Both keys and values for this map are strings. Because the keys are constant, they're stored in a final static array named keys. At various times I plan to use the keys as XML element names, XML attribute names, or SQL field names. Therefore, it's necessary to begin each of them with letters. Thus the keys for the fiscal year fields will be named FY1976, FY1977, FY1978, and so forth instead of just 1976, 1977, 1978, and so forth. This means we won't trivially be able to store the keys as ints. However, this turns out not to have been the case anyway because one of the year fields turns out to be the transitional quarter in 1976—which does not represent a full year and does not have a numeric name.


In 1976 the government's fiscal year shifted forward one quarter. As a result, the 1977 fiscal year started in October, a quarter after the 1976 fiscal year ended. There was a transitional quarter from July through September that year; therefore, some of the data actually represents less than a whole year. Here, the special case is very much a result of the data itself. Thus the data can't be fixed but still requires extra code, making the examples less clean than they otherwise would be.

This sort of funky data (a year with only three months in it that can easily be confused with another year) is exactly the sort of thing you have to watch out for when processing legacy data. The real world does not always fit into neatly typed categories. There's almost always some outlier data that just doesn't fit the schema. All too often it's been forced into the existing system by some manager or data entry clerk in ways the original designers never intended. This happens all the time. You cannot assume the data actually adheres to its schema, either implicit or explicit.

The code to parse each line of input is hidden inside the private splitLine() method. This code is relatively complex. It iterates through the record looking for comma delimiter characters but has to ignore commas that appear inside quoted strings. Furthermore, it must recognize that the end of the string delimits the last token. Even so, this method is not very robust. It will throw an uncaught exception if any quotes are omitted, or if there are too few fields. It will not notice and report the error if a record contains too many fields.

Example 4.1 A Class That Parses Comma-Separated Values into a List of HashMaps

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

public class BudgetData {

  public static List parse(InputStream src) throws IOException {

    // The document as published by the OMB is encoded in Latin-1
    InputStreamReader isr = new InputStreamReader(src, "8859_1");
    BufferedReader in = new BufferedReader(isr);
    List records = new ArrayList();
    String lineItem;
    while ((lineItem = in.readLine()) != null) {
    return records;


  // the field names in order
  public final static String[] keys = {
    "FY1976", "TransitionQuarter", "FY1977", "FY1978", "FY1979",
    "FY1980", "FY1981", "FY1982", "FY1983", "FY1984", "FY1985",
    "FY1986", "FY1987", "FY1988", "FY1989", "FY1990", "FY1991",
    "FY1992", "FY1993", "FY1994", "FY1995", "FY1996", "FY1997",
    "FY1998", "FY1999", "FY2000", "FY2001", "FY2002", "FY2003",
    "FY2004", "FY2005", "FY2006"

  private static Map splitLine(String record) {

    record = record.trim();

    int index = 0;
    Map result = new HashMap();
    for (int i = 0; i < keys.length; i++) {
      //find the next comma
      StringBuffer sb = new StringBuffer();
      char c;
      boolean inString = false;
      while (true) {
        c = record.charAt(index);
        if (!inString && c == '"') inString = true;
        else if (inString && c == '"') inString = false;
        else if (!inString && c == ',') break;
        else sb.append(c);
        if (index == record.length()) break;
      String s = sb.toString().trim();
      result.put(keys[i], s);

    return result;


  • + Share This
  • 🔖 Save To Your Account

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information

To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.


Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.


If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information

Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.


This site is not directed to children under the age of 13.


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information

If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information

Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents

California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure

Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact

Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice

We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020