Gradle : generating a jar from externally compiled classes

Question

I'm trying to generate a jar from a folder in which I manually compiled my classes.

Here is the task I put in place

task toJar (type: Jar) {
    from file('/path/to/classes/dir')
    destinationDir file('/path/to/jars/dir')
    with jar
}

But what that task doesn't generate anything. I've seen may examples with configurations.compile.collect but in my case the directory is compiled by an external tool.

How gradle can generate a jar from externally compiled classes ?

Answer 1

Your task should work fine, but you don't really need the with jar .

Below is a working example, assuming that the directory with externally compiled classes is $rootDir/externalClasses :

task toJar(type: Jar) {
    from file("$rootDir/externalClasses")
    destinationDir project.buildDir
    // print each included file for debug purpose
    eachFile { print "included file: $it" }
}

Output :

> Task :toJar
included file: file 'C:\tmp\gradle-projects\TestGradle\externalClasses\org\mycompany\gradle\MaiApp.class'
BUILD SUCCESSFUL in 0s
1 actionable task: 1 executed

The result Jar file is then properly created in $buildDir/

Can you try to remove the "with jar" line, and add the eachFile debug closure in your code? what is the output?