Reducing jar file size?

Question

Is there a good app to reduce jar file size by eliminating redundant classes/methods/constant pool elements? (i.e. not reachable from a fixed set of entry points, assuming no reflection)

I'm tired of pulling in bloated libraries when I'm just using a couple of methods from them.

(I'm not talking about small "local" optimizations like making names smaller. I'm thinking more of something that does global analysis to figure out which classes/methods/variables are used, given a set of entry points (including reflective entry points), and removes everything that is not used.

My webapp is like, 45MB, mostly due to 30-odd libraries, and I'm pretty sure I'm using only a small fraction of each library.

@hairraisin I think this will not make a difference (but I could be wrong) since `jars` are [already](http://en.wikipedia.org/wiki/JAR_(file_format)) zip archives (w/ some additional info). — om-nom-nom, Oct 18 '11 at 17:03

score 14 · Answer 1 · answered Oct 18 '11 at 16:57

14

Yes, there is one - Proguard.

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.

answered Oct 18 '11 at 16:57

om-nom-nom

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Thanks! and oh, is there something like this that will directly work on a war file? – user1001630 Mar 29 '13 at 19:46
@user1001630 you mean without unzipping? cause otherwise solution [is to use proguard anyways](http://stackoverflow.com/q/2477447/298389) – om-nom-nom Mar 29 '13 at 19:48
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I never achieved to do anything using proguard. It allways fails on any jar I tried. – Tomáš Zato Jan 04 '16 at 00:10

Grodriguez · Answer 2 · 2011-10-18T17:14:43.827

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Obfuscation typically reduces jar file size by a respectable factor.

You may want to try tools like Proguard (open source) and similar.

You can see some examples of size reduction in this page:

http://proguard.sourceforge.net/index.html#/results.html

edited Oct 18 '11 at 17:14

answered Oct 18 '11 at 16:57

Grodriguez

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score -1 · Answer 3 · answered Apr 30 '13 at 17:02

Just another nice trick, usually using the unnamed package, which is deleting the name (< default> will appear), also decreases the jar size.

In my case my jar went from 24,243 bytes to 23,946. Yeah not a big deal but still a cool trick i think.

From efficient MIDP programming:

"Use the 'unnamed package' – placing your MIDlet classes all in the same named package only increases the size of your MIDlet’s JAR file; reserve the package statement for libraries" http://carfield.com.hk/document/java/articles/Efficient_MIDP_Programming.pdf

Reducing jar file size?

3 Answers3

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