I'm working in Java development. I have recently come into a situation where I have to comply to coding standards: member and method ordering, naming conventions, modifier sequence. I am thinking about methods to either automate checking for compliance, or generate some sort of mechanism that does the reordering.
We're developing with Eclipse, but the technology would be open. One way it might work is to generate an external builder tool and add this to the projects. The disadvantage would be that it would automagically apply to all files, which could run into problems with legacy code, blowing up the error count to a degree where it is no longer a sensible metric of compliance. Also, it makes code reviews much more difficult, which is not wanted.
Another way would be some kind of parser with only informative capabilities. We could run a process inside Jenkins, and that certainly would work, but that would also mean that the code had already passed a review, which is usually a little late for a code compliance check.
Are there suggested or even easy methods to integrate such functionality into either IDE, the source control system (Mercurial) or even Jenkins? How is this enforced elsewhere?
I would not recommend doing such changes automatically. Even though most of the checkstyle/pmd complies are valid, it happens to me that I need to ignore some of the warnings/errors. Moreover - there is only very small pool of such easy issues. Most of the notifications require more complex operations and probably couldn't be done without human interaction.
I'm using Sonar integration. It contains many external checkers like PMD, CPD, Checkstyle, Findbugs and can integrate with some other useful tools like Cobertura (test coverage statistics). Its almost trivial to bind Sonar build to Jenkins build and trying to avoid major/critical issues might be considered as a good approach.
In developer environment I use Eclipse integration with findbugs. There is also some point of integration with sonar but it requires either submitting the code to server or running server locally, which I personally don't like. However after few cycles of polishing the code after code review in Sonar you will notice that you (and other team members) stick to most of the rules and checking reports on daily basis is enough.
One solution is to use JCSC / checkstyle or other tools that are command line friendly. Integrate this with your build process. Individual developer runs this on his branch.
Most tools integrate well with Jenkins (via plugins), which can be used as dash board
Further to #Jayan's answer, Jenkins has a CheckStyle plugin that will display the results of each CheckStyle run and let you set the build status depending on how many violations are found. So your setup steps would be:
Set up your CheckStyle rules to fit your coding standards
Add a step to your Jenkins build that runs CheckStyle
Add a post build step to publish the CheckStyle results.
Jayan mentions checkstyle, which is great for checking against coding standards.
I remember using Jalopy years ago for automated code formatting, it might suit your needs as well.
In all honesty though, I wouldn't reformat the code automatically. Using tools such as checkstyle to raise warnings is one thing. Taking control of a developer's source code is quite another, and most people find it terribly intrusive and unpleasant.
Also, a bug in a code checker will at worst generate incorrect warnings. A bug in a code beautifier might corrupt and destroy hours worth of work.
You can use JArchitect to check your best practice using CQLinq queries which is useful
to create easly your custom rules
JArchitect is free for open source contributors :http://www.jarchitect.com/JArchitectForOSS.aspx
I am trying to find the execution flow in a large java code base which is not written by me. I have searched for tools which make that possible (JSonde, JTrace, Java Call Tracert, JavacallTracer), but the problem is that they all should be used with a single java/jar/class file.
The code I am trying to understand is built with Ant and has hundreds of jars. So, it runs using a shell script. I do not know how to use those tools with this code.
I really appreciate your help.
I know, that this is an old question, but now I found a solution and I put it here if somebody else searches the same thing: http://findtheflow.io/#gettingstarted.
I think what you should consider is a code coverage tool. This will report what parts of your code are executed and which are not. There are several such tools to consider. Jacoco is an emerging favourite and is associated with the Emma Eclipse plugin.
The thing to remember about code coverage is that it needs to be driven by something. Normally this is accomplished by running your code's tests (unit or integration).
Finally, once you've comfortable with how to enable code coverage you could also consider uploading and archiving it's results in Sonar.
I'm using eclipse in a Java environment. I have to introduce testing to an already underway project. How to start? Unit tests on the classes, and what else? What are the best tools for the job (considering I'm using eclipse)? TestNG, JUnit, JTiger?
How do I make others adapt themselves to use the tests?
Thanks in advance!
Eclipse has a great support of JUnit. This looks like a great starting point. I would add a new source directory test and create a package structure mirroring your src folder. Then you can add your unit tests one by one. Good luck!
Unless your team already is used to writing tests, testing all old components is not really feasible (sometimes not even then), as writing testable software requires a specific mentality.
I think, the best time to start writing tests is when you can define some new component that is critical enough to warrant the extra effort, but somehow new, so the already existing code base would not be tested as much.
This way you could find a testing approach, identify the benefits and learning the mentality without putting too much effort in something that might not work for your team.
About tooling: I sadly cannot really compare the different tools, as I only have experience with JUnit.
JUnit is easy to start with, as the corresponding tooling is already included in Eclipse (wizards to create templates, running and evaluation options...), and there are plenty of documentation and examples available on the net.
A lot of good questions.
If your project does not tests at all and already underway you should introduce the tests incrementally. When you have to develop a new feature write test for this feature, classes that you are going to change and features that could be broken. The same is when you are fixing bugs. First write test that reproduces the bug, then fix it.
I used JUnit and TestNG. Both are almost the same. TestNG has groups, i.e. you can mark test to be belong to group like development, build, integration, etc. This is mostly relevant if you have a lot of tests and it takes significant time to run them all.
Do you already have automatic build? If not start from this. If you prefer to use maven it is relatively simple. When your build is ready write a couple of unit tests (just to have something to fail...)
Then install Hudson/Jenkins and define your project there. People will see how cool is it that once you commit your new code the build runs almost immediately and you see all failed tests. Probably try to show the strength of TDD to your boss and try to explain him that he should force all team members to write tests.
If you have enough energy introduce Sonar to your company. People will see how awful the code that they are writing and how poor the test coverage is. The they will see how quickly the test coverage is growing up and will probably invest more into unit testing.
Shortly, good luck. You are on the right way.
JUnit and TestNG are both fine. TestNG has more capabilities and can be helpful with integration tests, JUnit is more focused on unit tests.
You may want to get acquainted with some kind of mocking library like Mockito. Code coverage tools like Cobertura and continuous integration tools like Jenkins are great too.
Using a DI framework like Spring or Guice is helpful for writing more easily-testable code. Whether you use a DI framework or not, the more loosely-coupled your code the easier it is to test. Since your project is already under way it is probably too late for this part, which will make your task harder.
It can be very hard to get co-workers to cooperate with testing. You may want to introduce it selectively on pieces where it can make the most difference. Writing tests for already-finished functionality is usually painful and a waste of time. Tests should be small, have few dependencies, be understandable, and should run quickly. The more painful it is to write tests, run the tests, and fix broken tests, the more resistance you will get.
is it possible to hook up an agent or something to the jvm before starting up an application (or an appserver) and have a report showing how much of the code base in the classpath is actually executed for a given use case ?
I want to figure out how much code is left out unexecuted for my simple servlet application running in an appserver which doesn't use many j2ee technologies like JCA, JMS, CMP, etc.
Best regards,
Bulent Erdemir
What you're looking for is a code coverage tool.
For Java, I've had a great deal of success with EMMA. You should be aware that any code coverage tool is likely to affect performance significantly - typically it's used for unit testing, to check that your unit tests hit appropriate parts of your code. You could use it for a test run of a web app as well though - I'd just recommend against using it for the production deployment.
I prefer cobertura over EMMA. At least when I used EMMA it generated a number of false negatives (lines that were actually executed but it said they were not). EMMA may have fixed this.
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What tools do you use to find unused/dead code in large java projects? Our product has been in development for some years, and it is getting very hard to manually detect code that is no longer in use. We do however try to delete as much unused code as possible.
Suggestions for general strategies/techniques (other than specific tools) are also appreciated.
Edit: Note that we already use code coverage tools (Clover, IntelliJ), but these are of little help. Dead code still has unit tests, and shows up as covered. I guess an ideal tool would identify clusters of code which have very little other code depending on it, allowing for docues manual inspection.
An Eclipse plugin that works reasonably well is Unused Code Detector.
It processes an entire project, or a specific file and shows various unused/dead code methods, as well as suggesting visibility changes (i.e. a public method that could be protected or private).
CodePro was recently released by Google with the Eclipse project. It is free and highly effective. The plugin has a 'Find Dead Code' feature with one/many entry point(s). Works pretty well.
I would instrument the running system to keep logs of code usage, and then start inspecting code that is not used for months or years.
For example if you are interested in unused classes, all classes could be instrumented to log when instances are created. And then a small script could compare these logs against the complete list of classes to find unused classes.
Of course, if you go at the method level you should keep performance in mind. For example, the methods could only log their first use. I dont know how this is best done in Java. We have done this in Smalltalk, which is a dynamic language and thus allows for code modification at runtime. We instrument all methods with a logging call and uninstall the logging code after a method has been logged for the first time, thus after some time no more performance penalties occur. Maybe a similar thing can be done in Java with static boolean flags...
I'm suprised ProGuard hasn't been mentioned here. It's one of the most mature products around.
ProGuard is a free Java class file shrinker, optimizer, obfuscator,
and preverifier. It detects and removes unused classes, fields,
methods, and attributes. It optimizes bytecode and removes unused
instructions. It renames the remaining classes, fields, and methods
using short meaningless names. Finally, it preverifies the processed
code for Java 6 or for Java Micro Edition.
Some uses of ProGuard are:
Creating more compact code, for smaller code archives, faster transfer across networks, faster loading, and smaller memory
footprints.
Making programs and libraries harder to reverse-engineer.
Listing dead code, so it can be removed from the source code.
Retargeting and preverifying existing class files for Java 6 or higher, to take full advantage of their faster class loading.
Here example for list dead code: https://www.guardsquare.com/en/products/proguard/manual/examples#deadcode
One thing I've been known to do in Eclipse, on a single class, is change all of its methods to private and then see what complaints I get. For methods that are used, this will provoke errors, and I return them to the lowest access level I can. For methods that are unused, this will provoke warnings about unused methods, and those can then be deleted. And as a bonus, you often find some public methods that can and should be made private.
But it's very manual.
Use a test coverage tool to instrument your codebase, then run the application itself, not the tests.
Emma and Eclemma will give you nice reports of what percentage of what classes are run for any given run of the code.
We've started to use Find Bugs to help identify some of the funk in our codebase's target-rich environment for refactorings. I would also consider Structure 101 to identify spots in your codebase's architecture that are too complicated, so you know where the real swamps are.
In theory, you can't deterministically find unused code. Theres a mathematical proof of this (well, this is a special case of a more general theorem). If you're curious, look up the Halting Problem.
This can manifest itself in Java code in many ways:
Loading classes based on user input, config files, database entries, etc;
Loading external code;
Passing object trees to third party libraries;
etc.
That being said, I use IDEA IntelliJ as my IDE of choice and it has extensive analysis tools for findign dependencies between modules, unused methods, unused members, unused classes, etc. Its quite intelligent too like a private method that isn't called is tagged unused but a public method requires more extensive analysis.
In Eclipse Goto Windows > Preferences > Java > Compiler > Errors/Warnings
and change all of them to errors. Fix all the errors. This is the simplest way. The beauty is that this will allow you to clean up the code as you write.
Screenshot Eclipse Code :
IntelliJ has code analysis tools for detecting code which is unused. You should try making as many fields/methods/classes as non-public as possible and that will show up more unused methods/fields/classes
I would also try to locate duplicate code as a way of reducing code volume.
My last suggestion is try to find open source code which if used would make your code simpler.
The Structure101 slice perspective will give a list (and dependency graph) of any "orphans" or "orphan groups" of classes or packages that have no dependencies to or from the "main" cluster.
DCD is not a plugin for some IDE but can be run from ant or standalone. It looks like a static tool and it can do what PMD and FindBugs can't. I will try it.
P.S. As mentioned in a comment below, the Project lives now in GitHub.
There are tools which profile code and provide code coverage data. This lets you see (as code is run) how much of it is being called. You can get any of these tools to find out how much orphan code you have.
FindBugs is excellent for this sort of thing.
PMD (Project Mess Detector) is another tool that can be used.
However, neither can find public static methods that are unused in a workspace. If anyone knows of such a tool then please let me know.
User coverage tools, such as EMMA. But it's not static tool (i.e. it requires to actually run the application through regression testing, and through all possible error cases, which is, well, impossible :) )
Still, EMMA is very useful.
Code coverage tools, such as Emma, Cobertura, and Clover, will instrument your code and record which parts of it gets invoked by running a suite of tests. This is very useful, and should be an integral part of your development process. It will help you identify how well your test suite covers your code.
However, this is not the same as identifying real dead code. It only identifies code that is covered (or not covered) by tests. This can give you false positives (if your tests do not cover all scenarios) as well as false negatives (if your tests access code that is actually never used in a real world scenario).
I imagine the best way to really identify dead code would be to instrument your code with a coverage tool in a live running environment and to analyse code coverage over an extended period of time.
If you are runnning in a load balanced redundant environment (and if not, why not?) then I suppose it would make sense to only instrument one instance of your application and to configure your load balancer such that a random, but small, portion of your users run on your instrumented instance. If you do this over an extended period of time (to make sure that you have covered all real world usage scenarios - such seasonal variations), you should be able to see exactly which areas of your code are accessed under real world usage and which parts are really never accessed and hence dead code.
I have never personally seen this done, and do not know how the aforementioned tools can be used to instrument and analyse code that is not being invoked through a test suite - but I am sure they can be.
There is a Java project - Dead Code Detector (DCD). For source code it doesn't seem to work well, but for .jar file - it's really good. Plus you can filter by class and by method.
Netbeans here is a plugin for Netbeans dead code detector.
It would be better if it could link to and highlight the unused code. You can vote and comment here: Bug 181458 - Find unused public classes, methods, fields
Eclipse can show/highlight code that can't be reached. JUnit can show you code coverage, but you'd need some tests and have to decide if the relevant test is missing or the code is really unused.
I found Clover coverage tool which instruments code and highlights the code that is used and that is unused. Unlike Google CodePro Analytics, it also works for WebApplications (as per my experience and I may be incorrect about Google CodePro).
The only drawback that I noticed is that it does not takes Java interfaces into account.
I use Doxygen to develop a method call map to locate methods that are never called. On the graph you will find islands of method clusters without callers. This doesn't work for libraries since you need always start from some main entry point.