Sample Defect Cost Calculations: Why tests are worth it…

Sample Defect Cost Calculation

The cost calculation is not very simple and a lot of assumptions, and estimations are needed. The following definitions, terms, and formulas are a first step for an understanding of the costs related to defects and testing. Especially, the results shall be an example and maybe an argument for a strong and tight testing.

Let us define first the Defect Detection Percentage (DDP):

DDP [$] =  (bugs detected) / (bugs present) = (test bugs) / (test bugs + production bugs)

The defect detection percentage is a quite simple formula, because it is just the ratio of the bugs found before delivery to the total bugs in the code which is unknown. The real insight comes, as soon as the ratio is rewritten to the ratio of the bugs found during testing and the sum of the found bugs and the bugs which are delivered into production. This formula shows in a very simple manner the simple truth: All bugs which are not found during test go directly into production. The first ratio is to abstract to get this point straight with the right emphasis, but that is really important: Bugs in production at customer’s site destroy reputation, decrease future revenue due to lost customers, and in worst case bring in calls for liability.

The relationship of total found bugs to critical bugs found should be under all circumstances:

DDP (all bugs) < DDP(critical bugs)

Or in other words: It should be the final goal to have a much better detection percentage for critical bugs than for all bugs or minor bugs. It is in most cases not very critical to have a button in a UI at the wrong position, but a crashing application or an application which cannot keep a database connection open, is critical.

The consequence is: We should put more time and effort into testing of critical and blocking defects than on minor issue testing. I have seen this in real world already. The focus and the effort on the UI was remarkable, because it was obvious and everybody could see it (especially the own management and the customers management), but the performance was not sufficient and the stability was not as good as needed. But, the product was shiny and looked beautiful…

Have a look into the post about the quality characteristics: What is critical and what not may change from project to project. A deep though is needed for the weighting, but the weighting should lead the testing priorities.

The possible costs for defects (see Beautiful Testing: can be classified as:

  1. Cost of detection: All costs for testing and accompanying actions. Even if no bugs are found, there are costs which need to be taken into account. For example: Performing a quality risk analysis, setting up the test environment, and creating test data are activities to be taken into account. They all incur the costs of detection and there are much more tasks to do. These are the permanent costs on timely basis.
  2. Cost of internal failure: The testing and development costs which incur purely because bugs are found. For example filing bug reports, adding new tests for the found bugs, fixing bugs, confirmation test bug fixes, and regression testing are activities that incur costs of internal failure. These are the actual costs per bug.
  3. Cost of external failure: The support, testing, development, and other costs that incur because no 100% bug-free software was delivered. For example, costs for technical support, help desk organization, and sustaining engineering teams are costs of external failure. These costs are much higher. The costs are at least as high as the internal failure costs, but there are additional costs for external communication, containment, and external support.

Let’s define the Average Cost of Test Bug with the knowledge from above:

ACTB = (cost of detection + cost of internal failure) / (test bugs) [$/Bug]

There is also the definition of the Average Cost of a Production Bug:

ACPB = (cost of external failure) / (production bugs) [$/Bug]

With both definitions from above the calculating of a Test Return On Investment can be defined:

TestROI = ( ( ACPB – ACTB) x test bugs) / (cost of detection) [1]

Example Test ROI Calculation

Let us assume, we have 5 developers in a test team which cost about 50k$ per month (salary and all other costs). Let us further assume, they find an average of 50 bugs per month and a customer finds 5 bugs a month. The production bug cost is assumed with 5k$ (5 people for a week for customer support, bug fixing and negotiations) and a testing bug cost of 1k$ (1 developer for a week). We have the following numbers:

ACTB = (50 k$/month + 50 bug/month * 1k$/bug) / (50 bug/month) = (100 k$/month) / (50 bug/month) = 2k$/bug

ACPT = (10 bug/month * 5 k$/bug) / (10 bug/month) = 5 k$/bug (what we obviously defined)

TestROI = ((5 k$/bug – 2k$/bug) * 50 bug/month) / (50 k$/month) = 3

This simple example shows, that testing might be economically meaningful…

Automated and Manual Regression Tests

Some simple formulas for automated testing. It is sometimes difficult to communicate the positive impact of automated testing, because the initial costs for hardware, operational costs and the costs for development of automated tests are significant. But, the next formulas give an impression for the benefit.

Let us define the Regression Test Automation ratio:

RTA = (automated regression tests) / (manual tests + automated regression tests)

The Regression Risk Coverage is shown here to have the complete set of formulas:

RRC = (regression risk covered) / (regression risks identified)

The RRC is used as a measurement for the confidence on the automated tests. The higher the RRC, the better the confidence not to deliver critical bugs.

To calculate the benefit of automated test, the Acceleration of Regression Testing can be used:

ART = (manual regression test duration – automated regression test duration) / (manual regression test duration)

Automated tests bring benefits twofold:

  1. Development and test engineers are relieved from repetitive work. Engineers in most cases are not very good in this. Engineers are better placed inside of development projects and in failure analysis which brings more economical benefits. Every hour saved for manual testing can be better spend in functionality development or quality improvement.
  2. Automated tests can be run anytime, even during night. Continuous Integration (CI) and Continuous Delivery (CD) approaches use this by automated triggering of tests. Tests are run for example after each code change in the Source Code Management tool. Bugs can be found and fixed very quickly.

The costs can be lower, too. If the testing environment costs 1k$/month, it is about 1/5 of a developer, but it runs 24/7 and executes much more tests per time unit than any developer can do. It is a real bargain.


Even it is only a short post on some defect cost calculations, it shows that testing is meaningful economically. The costs for testing like developers developing automated tests, dedicated testers doing manual tests, hardware, QA staff managing testing and assuring the quality compliance, and so forth seem very high, but taken into account that the costs for defects increase significantly the later they are found in the product life cycle, testing brings a huge benefit.

Software Quality Charateristics in ISO 9126

In ISO 9126 software quality characteristics are defined which are used to evaluate the quality of a software product. These characteristics shall assure a complete evaluation, but in most projects these characteristics need to be weighted to each other. This evaluation procedure is quite complex and it differs from project to project and maybe also over time due to changing requirements (Agility). I want to give here a starting point for the discussion which is true in most projects, but need to be refined.

The Characteristics

The main software characteristics in accordance to ISO 9126 are:softwarequality-en

  1. Functionality
  2. Reliability
  3. Efficiency
  4. Usability
  5. Maintainability
  6. Portabilty

A graphical representation of this main characteristics and the sub-characteristics is show nearby. I already ordered them in correspondence to the importance for most software projects. But, this is only half of the truth. In the following sections the explanations are provided.


Security is divided into the following sub-characteristics:

  1. Suitability
  2. Accuracy
  3. Interoperability
  4. Security
  5. Functional Compliance

This is the most crucial point for customers. With incorrect results, unsuitable models and software which can not inter-operate with their environments, our software is useless. A software which has not the functionality needed, is never accepted by customers.


The sub-characteristics are:

  1. Maturiy
  2. Fault Tolerance
  3. Recoverability
  4. Reliability Compliance

Reliability is the second most important point in software development. As soon as the software has a certain functionality, this functionality needs to be available. This is needed to generate a constant revenue, to provide services to end user for their satisfaction or to monitor safety critical operations. A weak reliability will lead to loss of revenue, loss of customers and in critical area to injuries and deaths.


Sub-characteristics are:

  1. Time Behavior
  2. Resource Utilization
  3. Efficiency Compliance

Our customers have fabs where they try to increase the throughput on daily basis. Our software needs to be performant, too. We should pay some attention to performance and resource usage. But, this must no be on cost of maintainability. Ask your senior about the right decisions if unsure.


The sub-characteristics are:

  1. Understandability
  2. Learnability
  3. Operability
  4. Attractiveness
  5. Usability Compliance

Our customers and clients want software which is self-explanatory and easy to use. We should keep in mind to keep our customers happy with nice and usable GUIs, too.


Maintainability’s sub-characteristics are:

  1. Analyzability
  2. Changeability
  3. Stability
  4. Testability
  5. Maintainability Compliance

This is the most important point for ourself! Code which is not maintainable leads to code which can not be changed, can not be kept stable and secure and may lead into a product which can not be sold. On the other side, we can make our lifes much easier with easy to read and easy to write code.


The sub-characteristics for Portability are:

  1. Adaptability
  2. Installability
  3. Co-Existence
  4. Replaceability
  5. Portability Compliance

This point is of minor importance, but should be kept in mind by architects. The system itself and technologies used within our products are meant to change in future. We should build systems in a way, that sub-systems may be changed without too much work.

Sum Up

As I wrote before, the statements I made above will be true for most software products, but there are always differences from one project to another. The ordering above will lead into good software which is also sell-able, but it is kind of focused to technical

Let’s have a short look to Video Games: As far as I observe the market, the priorities are different here. Performance in Video and Realism (Efficiency) are one of the highest values and Reliability comes behind. In forums people talk about awesome graphics and realism, but they complain about stability issues within new products, but the products are bought nevertheless. It is the graphics which is valued most. Sometimes the functionality also is behind Efficiency. There are some video games out there with a very thin story, which are not intuitive to use, but which are bought for the cheer graphics and their open world.

Another example is software for end users: Here the Usability is ranked in most cases above Efficiency. End user need to have a good time using the software. Easy usage is much more important for them then waiting for some seconds for an operation to finish. The famous flying object which show activity, nice graphics and so forth are more important than efficiency. Have a look to one of the famous smart phone manufactures: There OS looks great, is easy to use and is stable. The functionality is not overwhelming, but it is stable and fast enough. The priorities are set right, but different then I wrote above.

5S Methodology and Software Development

The 5s methodology is used to keep the working environment clean, ordered and efficient. I came across this methodology when I was working in a production area for a semiconductor factory. This system was referenced from time to time when internal audits showed some weaknesses in regard to efficiency, order or cleanness. For a short reference on 5s methodology have a look to:

The key topics Sorting, Straightening, Shine, Standardize, and Sustain are quite weak translations of the Japanese words Seiri, Seiton, Seiso, Seiketsu, and Shitsuke due to the wish to translate it into English words which also start with the S letter. Nevertheless, they express roughly the idea behind that and details are explained below. Again like for the post about the Seven Muda, I also translate these topics into the field of Software Engineering as I understand it.

Sorting (Seiri)

This principle has a strong relation to the Muda Inventory, Over-Processing and Over-Production.

Classic meaning:

The meaning here is: Remove everything unnecessary. Check all tools, materials, and machinery and remove everything which is not needed. This cleans out the workspace, makes spaces and removes distraction. The rate of defects decreases due to a lowered risk to use wrong tools or materials and more space means less incidents.

Software Engineering:

For software engineering it is the same, but it is twofold:

  1. For development process: Remove all tools and stuff in your workspace, IDE or PC which is not needed. These tools distract the developer, make the workspace cleaner as mentioned above and also sometimes more stable (everyone who uses Eclipse with a lot of plugins know, what I mean).
  2. For Architecture and Design: Remove all components, interfaces, libraries, and systems which are not needed. These are added as soon as they are needed. For example: To implement everything in patterns right from the beginning does not make much sense, when  not needed, yet. The requirements may change and what was though at the beginning is needed, will not be needed further on. Only use and implement, what is needed and postpone everything else into the future when needed.

Not hitting the correct meaning, but also part of it is duplicate code. Duplicate code is something which is redundant. Redundancy is also something which needs to be cleaned out. Duplicate code is a nightmare for maintainability and should be avoided in all means.

Straightening (Seiton)

This principle has a relationship to Muda Transport, Motion and Waiting.

Classic meaning:

This principle is about straightening the processes. Everything should be processed in an efficient way. Transport ways need to be shortened, motions to be avoided, unnecessary tasks to be eliminated and wait time to be reduced. This principle can only be applied in iterations with close observations.

Software Engineering:

In software engineering this principle can be used as a driving factor for lean architecture and design. The Muda Transport, Motion and Waiting in post about the Seven Muda give hints were to look out in software engineering.

Shine (Seiso)

Classic meaning:

This is about cleaning and ordering the workspace. As soon as everything is clean and ordered, the station is ready for usage. In each shift or on daily basis, cleaning and ordering should be scheduled. On such a workspace, process flaws and defects are better to find and the work is easier, cleaner and safer.

Software Engineering:

For software engineering, I would refer to Clean Code and Refactoring. Write clean code and clean the code as soon as bad smells are detected. This keeps the code clean and erosion is prevented. Bugs are easier to spot in clean code and also easier fixed.

With refactoring the architecture and design stays clean, too. This assures an understandable architecture which support bug fixing and improvements.

These actions should take place during normal work, but also scheduled at the end of sprints for instance. Code Reviews can also set in place in critical parts of the software to assure the right measure of quality. A time budget from 5% to 50% depending of the state of the code should be scheduled. In brown field projects with a lot of legacy code massive cleanup can help to improve the later development of new functionality dramatically. But, also in green field projects erosion takes place and should be fought with a 5% time budget at least. Have a look to the books Refactoring by Martin Fowler and Clean Code by Robert C. Martin for details, or Working Effectively with Legacy Code by Robert C. Martin.

Standardize (Seiketsu)

Classic meaning:

In fabrications all work stations should be standardized, what means that they should look, function and feel all the same. It is more easy to train people on a new station that way, the quality is higher due to a lower defect rate and it is also cheaper if it is possible to reuse procedures, tools and material.

Software Engineering:

For software engineering, there are two possible meanings:

  1. All developers should use the same tools for development. It is more easy then to maintain a development environment where only one IDE is present, one build system, on OS and so forth. Only for testing there may be some variation, but for pure development, it is easier to deal with one kind of tool for one purpose.
  2. Within the software everything should be handled in a standardized way. So the architecture should define standards and also design. For instance it could be a standard that all components of a larger system communicate to each other with a REST interface. There only one REST library is used. It would be worse if all components would talk with another protocol like SOAP, RMI, EJB and so forth. For design it is the same. Exception handling for instance should be defined how it should be done. How are files handled? Coding guide lines and so forth.

Standards help that people can identify parts in larger systems more easily. Understandability and Maintainability improve dramatically.

Sustain (Shitsuke)

The first four points are hard enough to accomplish, but this sustaining point is even harder. What you did and accomplish in the first four sections is a large step to an efficient production environment. This is something which is done in form of a project, but a project is time limited. The real art of 5S is now to keep the state what was accomplished and to even improve it. That’s a huge leap! The goal is to establish a control system which checks for instance from time to time the current situation in a kind of internal audit and to raise the issues found. The issues should be fixed as soon as possible. With a regular check of the other 4S and an improvement of the findings, the current state can be sustained and even improved. But, this needs a lot of attention and energy.

In Software Engineering the buzz words Code Smell (or just Smell), Refactoring and Architecture Refactoring come to mind. As soon as there are bad smells, an action needs to be taken to fix this issue. The longer the issues is present, the more it manifests itself and the harder is it to be fixed. As the Asian proverb says: It is easy to change the direction of a river at its source…

Further Enhancements

Sometimes some enhancements are added. These points express some enhancements which should be taken care of, too. I only explain them shortly, because they are quite self explanatory.

Enhancement to 6S: ‘Get Used to it’ (Shukan)

This point is often added to the original 5S. With the checks and fixes in the Sustaining part, people get trained to keep an open eye on 5S. Over time everybody should develop a habit of fixing everything which is not in order to have an easier and more efficient life. It is good to create a company culture for 5S.


Classic meaning:

This is very easy: Keep everything and order and additionally, watch out for sources of accidents and prepare everything that this accidents cannot happen.

Software Engineering:

Here it is about the quality of source code and architecture for accidents like crashes, wrong results, stability and so forth.


Classic meaning:

Keep people out which are not supposed to be in certain area. Keep secrets secret and confidential data confidential.

Software Engineering:

Build  your software in a way that only authenticated people are allowed to change settings which they are authorized to and keep data protected from people which are not allowed to see them.

Thoughts on the Agile Manifesto

From time to time, I discuss the agile methodology with clients and friends. The Agile Manifesto was published at about 12 years ago. It was debated a lot and the debates still are going on. I try present here a small inside I had during the last years.

The main statement is

“Manifesto for Agile Software Development

We are uncovering better ways of developing
software by doing it and helping others do it.
Through this work we have come to value:

Individuals and interactions over processes and tools
Working software over comprehensive documentation
Customer collaboration over contract negotiation
Responding to change over following a plan

That is, while there is value in the items on
the right, we value the items on the left more.

Interestingly, the focus is shifted from the product, its documentation and the technical process (the planning) to customer focus and customer satisfaction. This is also part of another system which is called Total Quality Management ( The focus shift is very obvious and necessary, when we think about the only income source each company has: The customer. The customer (or different customers if an organization has different services to offer) is the only source for income and therefore for revenue, profit and growth. Any revenue increase can only happen, when customers pay more for services or products or more customers are willing to spend money on the companies services or products. It is therefore obvious, that the focus needs to be on the customer and that the organization needs to be aligned to meet the needs and expectations of customers.

That’s why the first point about ‘Individuals and interactions’ is the most important point. Translated to easy actions it means: Identify your customers, treat them individually and implement processes for easy communication and interaction. Only customers can tell you what they need, what they expect and what they are ready to pay for. Individual customers treated well, will tell you more detailed, what they need and bring new business ideas. Ask a group of people and there is no detail. But, ask a single individuals and listen closely. You might get a lot of insights.

In software development the main reason of organizations is delivery working software and systems. These are the primary needs of their customers. They do not need a fancy manual to read, what the software might be able to do after spending hours to read the manual and trying things out in tutorials, but they need a software which brings business value. That’s why the second point is important. Have a running, valuable software which is self-explanatory and the customer is willing to pay for it. You can save a tree by dropping the printed documentation. Have a look to Apple products. How much manuals are sold with this complex and feature rich software? Some only help and a self-explanatory UI and everything is fine. This is one of the fundamentals of Total Quality Management: Only the customer can tell you what she wants and she is also the one who pays. Is there another way to work with the knowledge?

The third point is the enhancement of the first point. If the chance is there, try to work with your customer closely together. In Scrum and XP it is done by short release cycles and demos to show the customer progress on regular basis after each release cycle and ask for critics, comments and new ideas. It helps to deliver software which is valuable for the customer and therefore, which is paid for. An even better idea is to embed a representative of the customer into the development team. The responses are immediate and customer’s acceptance testing is done the whole time. The possibility of developing software for what the customer does not want to pay, is reduced dramatically. And again: The customers pays for the product. There is no way to make a better product than to build the product together with your customer and when the customer is part of the team, she is even more engaged and willing to help for development. At the very end, the willing to pay is much higher, when the product was kind of custom built.

By doing all this, be prepared: With each demo, feedback session and communication to the customer, there might be new ideas, comments and critics. The requirements are about to change on daily basis. That’s what the fourth value is about. Be open for changes. Customer only have vague idea at the beginning, about what they want. But, during the development, more ideas arise, some faulty ideas are dropped and new wishes pop up. That’s kind of normal and part of the process. This helps to make the product better at the end and the business value is increased. A product like that can be priced higher, though. What is better than that?

Is “good enough” good enough?

I thought about the term “good enough” lately. It came into my mind, that the term is used in a kind of way which is misleading.

In a lot of books about quality and economics (books which deal with the combination of the two) it is written, that development should not be perfect, because it is economically not meaningful, but it should be good enough. The hint is right, but misleading. It is not explained in detail what ‘goo enough’ really means, at least not in the books I wrote about that topic.

The term good enough is treated in almost all cases I witnessed as: Good enough = Good enough to be sell-able. This leads to a focus on external design, usability and feature bloat to increase market value. The market value in most cases is only judged by the external attributes. Most buyers do not look into the products and judge the internal value, what in most cases also would not make much sense. That’s why colorful products, well-designed and products with a ton of features can be sold best.

There is nothing wrong about the fact that such products can be sold best and most easy, but from the business point of view, this is not enough. What is good enough for the end customer, is not necessarily good enough for the producer of the product. All products have more needs than just to be sell-able. Products need to be recyclable, maintainable, ecological and maybe also upgradable (and much more). These thoughts lead to the conclusion, that there is more to think about than just the market and to be good enough for the market.

In software industry for instance, the source code of a current product is used as foundation for all further products. As soon as the source base gets unmaintainable, all future products are in danger. Software is very complex to develop and therefore, very expensive. A complete new development of a source base of a product family is very expensive and only large companies can handle and survive that.

It is therefore very important, right from the beginning, to spend some effort on code quality. The application of metrics, defect checks and conventions is crucial. Otherwise, the future of a company can be in danger.

Thoughts on New Technologies in Software Projects

For all customers questions arise sooner or later about technology upgrades and changes in platforms, languages and APIs. When should it be done? To what technologies? How to handle the transformation? The questions can not be answered here, because it is a question which leads to different answers in different organizations, projects and teams.

One criterion to think about is standardization. In a lot of cases it is best to wait until a technology has reached a certain kind of standardization. The technology is supported then for a longer time without to much change and some backward compatibility. Some basic behavior and interfaces are quite fixed and are not to be expected to change to much in a short time. This is especially important for smaller organizations which can not handle too much change in a too short time range due to resource deficits. It can be more safe to wait until some standardization documents are out and some bigger players in the market have fixed some details and have committed their interest. The investment in a new technology is more safe afterwards.

A good example are OpenGL and OpenCL. OpenGL is a long time out now and is one of the standards for 3D graphics programming. It is expected, that OpenGL will evolve over time, but it is not to be expected to be disappearing in a short time range without any notification. To much companies and organizations are involved in the standardization process. One of the next big things might be OpenCL. With companies like Apple, Intel, AMD (, ATI), nVidia,… the list of supporters is long and technologies are evolving.

A wise decision to a new technology leads automatically to a competitive advantage due to the fact that competitors on the market might not have migrated, yet. The own organization’s products are faster, more accurate, more flexible. more easy to use or what so ever. One only has to be aware not to create an incompatible product.

With a change to a new technology one also should think about to put a kind of fall-back mechanism in which might change internally to a former implementation of the functionality to enable customers which might not have the latest technology available to use the own products. For OpenCL as an example, this might lead to a check for OpenCL compatible hardware and if not present to a fall-back to the older implementations. This slows down the application to a former level, but the customer is able to use the product which is more important than having the best performance.

These are just some thoughts on technology migration which came to my mind during some discussions with customers and managers. One should take care about the decision about new technologies. Not to change is not an option and it is also not an option to change the technologies every time there is something new at the market. One has to find the own speed and the right time for one self.

I18n and L10n in current software developments

When I have a look to current software developments and have in my mind the current process of a world becoming smaller and smaller, I start to wonder, why there is no more attention drawn to internationalization (I18n) and localization (L10n).

Why should be software be internationalized?

As long as their are only engineers and managers using my software, it might be OK to assume that my potential users are speaking English. On the opposite, my experience is that especially in Asian countries managers and engineers are not speaking very well. Some of the countries are not open for global business long enough that their  ‘older’ managers and engineers had no chance to learn and train English a long time. Young managers and engineers are to be expected to be better in speaking English, but as soon as one knows the significant differences in eastern and western languages, one knows, that there will still be a significant amount of people not speaking English so well. I know from experience what it means to lean a sino-tibetean language by learning Vietnamese myself.

It is even worse for software used by operators and fabrication staff. Imagine a MES system not localized to the language of the country. Even in Germany operators are not well educated in English. Should I prefer an English speaking MES system or a German speaking one? If the price, the functionality and the performance are almost equal, I prefer a German speaking system. If I would purchase the software for an international working cooperation, I would invest in multi-lingual software.

Marketing requirements

If I would develop software for a global market, I need to have to pay attention to meet the demand of as many people as possible to increase the number of potential customers to increase my sales. One of the easiest things to do is to present cutting edge software to customers in their mother tongue and physical units and time presentation in a way the customers are used to. If I worked in Vietnam, I would like to be able to switch my computer from Vietnamese to English (or even better: German). I would have a chance to use my computer in a more efficient way, to make less mistakes and to deal with the software in a more reliable way. I guess, this is also valid for a lot more people.

Quality Management

“Usability” is also a quality requirement. Have a look to PureSol Technologies website for some more information.The positively influenced characteristics are “Understandability”, “Learn ability” and “Operable”. For quality focused software projects this is also a factor to take into account.

Simple Conclusion: Do it

In current software developments we should always start projects with an additional focus on I18n and L10n. The additional time and work to enable my software to change the language and the output units is not that high. Using good frameworks for that, it’s very easy to achieve.

A simple framework example: I18n4Java

Let’s have a look to I18n4Java. It’s a small framework I created for my own applications. It’s stable and usable, but not very user friendly, yet. The L10n functionality is taken from the Java API. It’s a very good and reliable framework. Only the suggestopm for I18n implementation I did not like. The SUN recommendation can be found at The basic information is: Put all messages in property files and change them in reference to the language needed to be displayed.

This approach has some issues:

  1. The message to be display is separated from the source code. I need to look into additional files to find what is actually display. When I need to change messages, I need to open additional files.
  2. The situation is worse as soon as I need message with parameters. Without seeing the actual message, I do not know in which order I need to put the parameters into the message.
  3. I need extra codes for opening the properties files, additional error handling during loading errors and extra code to read the messages.

This limitations are overcome by I18n4Java. Additionally, it is very easy to use in code.

The only things to do is to add a translator to a class which needs I18n. In each class one just needs to create a Translator object:

private static final Translator translator = Translator.getTranslator(ClassName.class);

Afterwards within the class I only need to put every message to be displayed in to the translator and to show the translated message:

JMenuItem menuItem = new JMenuItem(translator.i18n("Menu Item Name"));

The message is then automatically translated into the language selected with


and if an translation file is found for the selected language.

That’s all what is to be done to enable I18n in Java programmed software. The rest is a simple configuration file to set the language needed. I18n4Java automatically sets itself to the currently set OS locale and tries to translate everything in the language the OS is set to.

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