groovy - How to make a task to call a main class -

what trying make task in build.gradle execute main class (class main method), don't know how.

i made test project test how that. here file structure layout:

testproject/     build.gradle     src/main/groovy/hello/world/helloworld.groovy 

here content of build.gradle:

apply plugin: 'groovy' apply plugin: 'maven'  repositories {     mavencentral() }  dependencies {     compile     'org.codehaus.groovy:groovy-all:2.0.6' }  task( hello, dependson: jar, type: javaexec ) {     main = 'hello.world.helloworld' } 

here content of helloworld.groovy:

package hello.world  class helloworld {     public static void main(string[] args) {         println "hello world!"     } } 

here shell:

testproject>$ gradle hello :compilejava up-to-date :compilegroovy up-to-date :processresources up-to-date :classes up-to-date :jar up-to-date :hello error: not find or load main class hello.world.helloworld :hello failed  failure: build failed exception.  * went wrong: execution failed task ':hello'. > process 'command '/library/java/javavirtualmachines/jdk1.7.0_25.jdk/contents/home/bin/java'' finished non-zero exit value 1  * try: run --stacktrace option stack trace. run --info or --debug option more log output.  build failed  total time: 4.232 secs 

so, question is: how can make gradle hello work? thank much.

after bit of googling, found solution. thing need change task block. working 1 pasted below:

task( hello, dependson: jar, type: javaexec ) {     main = 'hello.world.helloworld'     classpath = sourcesets.main.runtimeclasspath }