Including all the jars in a directory within the Java classpath

Question

Is there a way to include all the jar files within a directory in the classpath?

I\'m trying java -classpath lib/*.jar:. my.package.Program and it is no

Answer 1

Short Form: If your main is within a jar, you'll probably need an additional '-jar pathTo/yourJar/YourJarsName.jar ' explicitly declared to get it working (even though 'YourJarsName.jar' was on the classpath) (or, expressed to answer the original question that was asked 5 years ago: you don't need to redeclare each jar explicitly, but does seem, even with java6 you need to redeclare your own jar ...)

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Long Form: (I've made this explicit to the point that I hope even interlopers to java can make use of this)

Like many here I'm using eclipse to export jars: (File->Export-->'Runnable JAR File'). There are three options on 'Library handling' eclipse (Juno) offers:

opt1: "Extract required libraries into generated JAR"
opt2: "Package required libraries into generated JAR"
opt3: "Copy required libraries into a sub-folder next to the generated JAR"

Typically I'd use opt2 (and opt1 was definitely breaking), however native code in one of the jars I'm using I discovered breaks with the handy "jarinjar" trick that eclipse leverages when you choose that option. Even after realizing I needed opt3, and then finding this StackOverflow entry, it still took me some time to figure it out how to launch my main outside of eclipse, so here's what worked for me, as it's useful for others...

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If you named your jar: "fooBarTheJarFile.jar" and all is set to export to the dir: "/theFully/qualifiedPath/toYourChosenDir".

(meaning the 'Export destination' field will read: '/theFully/qualifiedPath/toYourChosenDir/fooBarTheJarFile.jar' )

After you hit finish, you'll find eclipse then puts all the libraries into a folder named 'fooBarTheJarFile_lib' within that export directory, giving you something like:

/theFully/qualifiedPath/toYourChosenDir/fooBarTheJarFile.jar
/theFully/qualifiedPath/toYourChosenDir/fooBarTheJarFile_lib/SomeOtherJar01.jar
/theFully/qualifiedPath/toYourChosenDir/fooBarTheJarFile_lib/SomeOtherJar02.jar
/theFully/qualifiedPath/toYourChosenDir/fooBarTheJarFile_lib/SomeOtherJar03.jar
/theFully/qualifiedPath/toYourChosenDir/fooBarTheJarFile_lib/SomeOtherJar04.jar

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You can then launch from anywhere on your system with:

java -classpath "/theFully/qualifiedPath/toYourChosenDir/fooBarTheJarFile_lib/*" -jar  /theFully/qualifiedPath/toYourChosenDir/fooBarTheJarFile.jar   package.path_to.the_class_with.your_main.TheClassWithYourMain

(For Java Newbies: 'package.path_to.the_class_with.your_main' is the declared package-path that you'll find at the top of the 'TheClassWithYourMain.java' file that contains the 'main(String[] args){...}' that you wish to run from outside java)

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The pitfall to notice: is that having 'fooBarTheJarFile.jar' within the list of jars on your declared classpath is not enough. You need to explicitly declare '-jar', and redeclare the location of that jar.

e.g. this breaks:

 java -classpath "/theFully/qualifiedPath/toYourChosenDir/fooBarTheJarFile.jar;/theFully/qualifiedPath/toYourChosenDir/fooBarTheJarFile_lib/*"  somepackages.inside.yourJar.leadingToTheMain.TheClassWithYourMain

restated with relative paths:

cd /theFully/qualifiedPath/toYourChosenDir/;
BREAKS:  java -cp "fooBarTheJarFile_lib/*"                                package.path_to.the_class_with.your_main.TheClassWithYourMain    
BREAKS:  java -cp ".;fooBarTheJarFile_lib/*"                              package.path_to.the_class_with.your_main.TheClassWithYourMain   
BREAKS:  java -cp ".;fooBarTheJarFile_lib/*"   -jar                       package.path_to.the_class_with.your_main.TheClassWithYourMain   
WORKS:   java -cp ".;fooBarTheJarFile_lib/*"   -jar  fooBarTheJarFile.jar package.path_to.the_class_with.your_main.TheClassWithYourMain   

(using java version "1.6.0_27"; via OpenJDK 64-Bit Server VM on ubuntu 12.04)