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This is along similar lines as these recent questions:
Best Java Obfuscation Application For Size Reduction
Creating non-reverse-engineerable Java programs
However, one ends up recommending yGuard and the other ProGuard but neither mention both. I wonder if we could get a comparison of each one and hear peoples experiences from both sides of the fence. Looking at this comparison chart on the ProGuard website its clearly angled towards ProGuard. But what about real-world experience of each - which one produces smaller output? which one is harder to decompile from? what Java versions are supported by each?
Personally I'm particularly interested from a J2ME point of view but please don't limit the discussion to that.
Results for my project.
Obfuscation - both fine.
Optimisation - ProGuard produced 20% faster code (for the measured app bottleneck).
Compactness - ProGuard about 5% smaller.
Configuration / Ant - YGuard is much easier to configure.
So, I'd advise ProGuard - but configuration and ant integration could definitely be improved.
Proguard is a better product; especially if you take the time to go through the settings for J2ME.
Specifically for J2ME there is a far better (commercial) product called mBooster
I've been getting around 25% improvement in size on my application after its been through Proguard. This is mainly to do with the better Zip compression on the Jar file and comprehensive support for class merging and preverification.
My opinion is - ProGuard is better. Output is smaller a bit. Optimizing is better and much faster.
Decompiling is simple in both cases. Well, i mean, if u know Java well and really know business-logic of what you're decompiling, there is no problem to get it back to sources from obfuscated classes.
So, my opinion is ProGuard is better.
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I am a university student that has been working with java now for a few years. I have been using eclipse in that time, but I have started to take a look at intellij idea. One big thing that I am interested in is battery. At most times, I am using my macbookto program. The biggest issue I have with it is trying to get the most out of the battery as using a IDE + testing programs can use quite a bit of power. Does anyone know which IDE (IntelliJ IDEA / Eclipse) would be better on the battery, or do you know any tips that could improve the battery life using either IDE?
This question will result in opinionated answers+this not about programming. There are no definite tests on finding which uses less battery power.
As Daemon said the difference in power consumption is minimal/insignificant.
What you should be asking are the objective differences between either IDE. Many people have asked that on Stackoverflow, so you should look into that. The following link shows some objective differences between the two: Differences between Eclipse and IDEA
However, IDEA does come with a Power Save Mode; not sure if that's relevant to you? From the DOCS: Power Save Mode Select this check box to minimize power consumption of your computer on account of eliminating the background operations. When Power Save Mode is on, no inspections are performed.
I suggest you carry around a battery charger.
Notepad++ makes for a functional code editor without the extra features that add processing overhead (which is likely draining your battery somewhat, but not much).
In all seriousness however, you'll find that the difference between IDE's in terms of power consumption is minuscule, and can safely be ignored. If you want to see real improvement in battery life, consider switching to a less performance-hungry operating system, such as Arch Linux.
If you're still concerned, consider stripping Eclipse or IntelliJ down to the bare minimum feature set required by your work.
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I heard there is software available that you can feed Java-code and it gives you back an indication on where your code is likely to produce unexpected behaviour. However, I cannot find such software, nor anything resemblng this. Does anyone have an idea on where to look? (I don't know where I heard this, so no, I cannot go back to the source and ask :( )
For example:
-it might check whether the same code is found at multiple places (when editing you are likely to forget to update one of the two, hence this could give prblems in the future)
-it might check whether you might be returning null somewhere where the null stays untreated,
-it might check for 'magic numbers' (numbers that are used in code without being assigned to a variable), especially when these numbers appear at various places in the code.
-etc, etc.
(What it doesn't need to check is whether the code can be compiled. that's, ofcourse, where we have already many other tools for, like Eclipse).
I do not know for certain whether the described software exists and what it looks like, but any help in this direction would be great!
Sounds like the code inspections you find in IntelliJ Idea.
There is FindBugs which does a static code analysis to find "bug patterns". That is code that falls in one of these category:
Difficult language features
Misunderstood API methods
Misunderstood invariants when code is modified during maintenance
Garden variety mistakes: typos, use of the wrong boolean operator
It's nice to use and tends to find some bugs. However it can not do everything you want (i.e. "returned null" checks).
There are a few tools like this. I've found PMD and Findbugs particularly useful.
findbugs is one such tool. More generally, what you're talking about is called static analysis.
If you work with eclipse, you could use codepro
Use sonar. It is a web application that has all these functionality and nice UI. Visit the site (http://www.sonarsource.org/) and see nemo - the live instance where all jakarta projects are hosted: http://nemo.sonarsource.org/
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I am in a project where previous programmers have been copy-pasting codes all over the place. These codes are actually identical (or very similar) and they could have been refactored into one.
I have spent countless hours refactoring these codes manually but I think there must be a better way. Some are very trivial static methods that could have been moved into an ancestor class (but instead was copy pasted all over by previous junior programmers).
Is there a code analysis tool that can detect this and provide reports/recommendations? I prefer free/open source tool if possible.
I use the following tools:
PMD/CPD (BSD-style License).
Checkstyle (LGPL License) - support was removed, see details.
Both tools have code duplication detection support. But both of them lack the ability to advise you how to refactor your code.
JetBrains IntelliJ IDEA Ultimate has good static code analysis with code duplication support, but it is not free.
Most of the tools listed on the Wikipedia article on Duplicate Code Tools will detect duplicates in many different languages, including Java.
SonarQube can detect duplicated codes but does not give recommendation on eliminating them. It is free and - although with the default setup it can only detect lexically identical clones
Either Simian or PMD's CPD. The former supports a wider set of languages but is non free for commercial projects.
http://checkstyle.sourceforge.net/ has support for finding duplicates
See our SD Java CloneDR, a tool for detecting exact and near-miss duplicate code in large Java systems.
The CloneDR will find code clones in spite of whitespace changes, line breaks, comment insertions deletions, modification of constants or identifiers, and in a number of cases, even replacement of one statement by another or a block of statements.
It shows where each set of clones is found, each individual clone, an abstraction of the clones having their shared commonality and parameterization of the abstraction to show how each clone instance can be derived from the abstraction.
It finds 10-20% clones in most Java systems.
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Is there an open-source Java implementation of the VCDIFF binary diff format (decoder and encoder)?
There are xdelta and open-vcdiff, but those are both C libraries.
Alternatively, are the other formats/algorithms that one could use to generate diffs for binary files from Java?
You can generate binary diffs using badiff; the website is
http://badiff.org/
and it is available on maven central. It's BSD licensed, so friendly for both OSS and commercial. The algorithm used is a chunked version of the O(ND) diff described in this paper:
http://www.xmailserver.org/diff2.pdf
The diff format isn't particularly compatible with anything else, but it produces some really good and really small diffs.
The library is pretty fast; on my desktop machine it can generate a diff for two random 50MB input streams in 54 seconds. Hopefully that's fast enough; I think it's reasonably impressive since that's a comparison of two token streams of 50 million tokens each. badiff will take advantage of multiple CPU cores when computing diffs.
disclaimer: I'm the author of badiff, so of course I think it's cool. I'm always open to suggestions; things like being able to read/write "standard" binary diff formats sound like cool new features to add in upcoming releases.
I have a decoder for VCDIFF written in C#, which would probably be fairly straightforward to port to Java, if that's any help. It's part of MiscUtil but I don't think it relies on any other bits of MiscUtil (or only minimally, anyway).
Unfortunately I never got round to writing an encoder, which is obviously rather harder - and wasn't necessary in our case (where we needed to apply patches in .NET on a mobile device, but could create them however we wanted at the server).
I hava ported MiscUtil's vcdiff decoder to java.
https://github.com/xiaxiaocao/jvcdiff
update: now it also have a vcdiff encoder
There is a java-port of xdelta:
http://sourceforge.net/projects/javaxdelta/
But i can not say anything on its quality - i did not try it yet.
I have a Java port of open-vcdiff on Github. It's tested against open-vcdiff, but it's not used in production anywhere.
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I'm looking for a good Java obfuscator.
I've done initial research into the following Java obfuscators: proguard, yguard, retroguard, dasho, allatori, jshrink, smokescreen, jobfuscate, marvin, jbco, jode, javaguard, jarg, joga, cafebabe, donquixote, mwobfu, bbmug, zelix klassmaster, sandmark, jcloak, thicket, blufuscator, and java code protector.
I tried proguard and it has a really nice GUI, seems really stable, and seems to be the most popular, but it seemed to not like some enumeration on a referenced jar file (not within the code I was trying to obfuscate) which was weird. Yguard seems to require some interaction with ant, which I didn't know too much about.
What is a good java obfuscator? It doesn't need to be free, it just needs to work well and be easy to use.
I use ProGuard heavily for all my release builds and I have found it is excellent. I can't recommend it enough!
I have encountered obscure bugs caused by it's optimizations on several occasions and I now disable optimizations across the board - haven't had a problem caused by ProGuard since. Though, to be fair, these were all quite some versions ago - YMMV.
I used to use the GUI only to get a config started, and then I resort to editing the text config myself, which is really very simple to do. These days I do the config by hand.
I have quite complex projects all of which involve dynamic loading and reflection. I also heavily use reflection for a callback implementation. ProGuard has coped with these very well.
EDIT: We also use DashO Pro for one of our products - I looked into it for packaging the products I am responsible for and concluded that it's configuration was too convoluted and complex; also integrating it into the build script seemed like a bit of a pain. But again, to be fair, this was circa 2001... so it might be better in current versions.
A good collection of links to free and commercial tools is given in this arcticle
"Protect Your Java Code - Through Obfuscators And Beyond"
The author also discusses the strong and weak points of bytecode obfuscation
What is the issue with ProGuard ? (which is recommended both by this question and this one).
There is a section of troubleshooting about enumerator, but they seem to be taken into account just fine.
However, Obfuscation breaks some attempts at reflection, even though modern obfuscators can detect and to some extend adjust usages of reflection in the code they're obfuscating.
I used Zelix Klassmaster in a commercial application for several years and found it to be excellent. I threw quite a few resources at the obfuscated code, and was not able to "break" it. It's pricey, but good.
I only stopped using it when my version got old enough that the upgrade cost was significant. My needs had changed and I didn't really need to obfuscate the classes anymore. However, if the need arises again, I'd pay for it and use it in a flash.
Cheers,
-Richard
We are using Zelix Klassmaster for couple years and I can recommend it.
I use and suggest Zelix - 100% - very solid and robust protection