“duplicate entry” error when exporting Java project to JAR with Eclipse

Question

I am trying to exort a Java project with Eclipse 3.6.1 to a runnable Jar. This used to work properly but failed today, afer I added some additional Jars to my class path.

Answer 1

You could try modifying the line

<jar destfile="/Volumes/resi/talosBase.jar" filesetmanifest="mergewithoutmain">

in your build file to be

<jar destfile="/Volumes/resi/talosBase.jar" filesetmanifest="mergewithoutmain" duplicate="preserve">

This will cause ant to preserve the first entry of any duplicate and ignore the rest. The default behavious is "add" so you can end up with multiple files of the same fully qualified name. The other valid entry for this paramter is "fail" but I don't think that will help you here.

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OLD-Answer

Delete your last created runnable jar either manually or alter the generated ant script to do so before creating a new one

Answer 2

I too had the same problem, but then I slightly modified the build settings in Eclipse to the one mentioned below.

This solved the duplicate entry issue for me, it just copies all required jars to a subdirectory.

Answer 3

Cleaning the project should help. It is not eclipse bug, but rather jar maker's one. Apparantly, it takes the classes and see that such classes already exist and can't understand that it should replace them instead of adding.

Answer 4

Try removing the jars and adding it once again.. this got the error resolved for me..

Answer 5

Cleaning the project will help you.

Answer 6

in my case cleaning the project doesnt change any thing so i use a workaround :

1. genearte a build script by activation by save ANT script ant script genration
2. execute the ant script manually or in eclipse (its better) executing script by eclipse

and I change my ant build script by adding option as indicate in this post duplicate="preserve" (to keep the first version on the duplicated file )

hope it help