Gradle - Could not find or load main class

77

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.

This question is tagged with java spring gradle build.gradle

~ Asked on 2014-07-24 04:05:28

The Best Answer is


75

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"
    

~ Answered on 2014-07-24 04:14:27


31

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'
    }
}

~ Answered on 2015-09-10 14:34:44


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