Configuration compile and runtime for gradle

Question

I set up a classpath for my jar reference inside a jar.('classpath: 'wee.jar'), but apparently, I also need to type the following in my jar task

from {
    configurations.compile.collect {
        it.isDirectory() ? it : zipTree(it)
    }
    configurations.runtime.collect {
        it.isDirectory() ? it : zipTree(it)
    }

Can Someone explain to me what does from, configuration.compile.collect, runtime, and isDirectory and zipTree do? I look up google, but couldn't find any answer. I'm really new to gradle

Answer 1

For starters, you do not need both configurations.compile and configurations.runtime. In gradle, the compile time dependencies are already included in runtime config automatically - which makes compile a subset of runtime. Depending on what you're trying to achieve, you'll only need one or the other. So let's take this snippet:

configurations.compile.collect {
    it.isDirectory() ? it : zipTree(it)
}

A configuration represents a collection of artifacts and their dependencies. compile and runtime are among configs that are added by the java plugin. collect is groovy for: do the following operation for every element of a collection and return the result as a set. So effectively the line of code translates to - for all dependencies declared in configurations.compile, do the following and return the results as a set.

it is groovy shorthand for iterator - so it represents each element of the aforesaid collection.

if `it` is a directory
    include it as is, 
else
    unpack the file and then include it

(See zipTree reference here)

Putting the whole thing together, the code is taking all compile time dependency directories and all unpacked compile time jars and including that into the jar you're building.