Gradle - Could not find or load main class

Question

I'm trying to run a very simple project using Gradle and running into the following error when using the gradlew run command:

could not find or load main class 'hello.HelloWorld'

Here is my file structure:

SpringTest     -src         -hello             -HelloWorld.java             -Greeter.java     -build          -libs          -tmp     -gradle          -wrapper     -build.gradle     -gradlew     -gradlew.bat 

I excluded the contents of the libs and tmp folders because I didn't think that would be relevant information for this issue, but I can add it in if need be.

Here is my build.gradle file:

apply plugin: 'java' apply plugin: 'application' apply plugin: 'eclipse'  mainClassName = 'hello/HelloWorld'  repositories {     mavenLocal()     mavenCentral() }  dependencies {     compile "joda-time:joda-time:2.2" }  jar {     baseName = "gs-gradle"     version = "0.1.0" }  task wrapper(type: Wrapper) {     gradleVersion = '1.11' } 

Any idea on how to fix this issue? I've tried all sorts of things for the mainClassName attribute but nothing seems to work.

Answer 1

I see two problems here, one with sourceSet another with mainClassName.

1. Either move java source files to src/main/java instead of just src. Or set sourceSet properly by adding the following to build.gradle.

   sourceSets.main.java.srcDirs = ['src'] 

2. mainClassName should be fully qualified class name, not path.

   mainClassName = "hello.HelloWorld" 

Answer 2

Modify build.gradle to put your main class in the manifest:

jar {     manifest {         attributes 'Implementation-Title': 'Gradle Quickstart',                    'Implementation-Version': version,                    'Main-Class': 'hello.helloWorld'     } }