Grouping Jar's Under lib

Question

The external jar files are placed under /Library/Java/Extensions on Mac OS X, i have multiple applications that depend on a group of jars such as JavaMail Api, if i dump all the jars in the folder java picks them up, but what i want to do is group them together such as all mail api jars go to the mail folder. But if group them under folders they are not picked up by java. Do i have to just dump them in to Extensions folder? It would make my life a lot easier when updating to group them.

Answer 1

• No, they should resize directly under /Library/Java/Extensions/.

• However, you can always pass -Djava.ext.dirs=... as an additional argument when you invoke Java programs.

• As a sidenote: If you're about to manage dependencies for your projects, try look into build tools, which declaratively resolve dependencies, such as ant.apache.org/ivy or maven.apache.org.

Answer 2

You should not use the global extensions library unless you really, really have to.

Basically your programs should be self contained units with library code on top of a stock JVM, this will allow different programs to have different requirements regardring library code versions, and it will also work when used on other machines.

Pick a good IDE (Eclipse, NetBeans, perhaps Xcode but I have not used it) and learn to add jar files to your projects. It will make you a more attractive programmer to a future employer.

Answer 3

I do find this behaviour annoying myself, that you have to have a flat folder structure when referencing external jars (if you don't add the jars individually).

However, if you don't mind grouping them into jar files instead of grouping them into folders, I would recommend One-Jar.
Quoting: "One-JAR uses a classloader which knows how to load classes and resources from Jar files inside a Jar file. "