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 l

Answer 1

I just ran into this problem and decided to debug it myself since i couldn't find a solution on the internet. All i did is change the mainClassName to it's whole path(with the correct subdirectories in the project ofc)

    mainClassName = 'main.java.hello.HelloWorld'

I know it's been almost one year since the post has been made, but i think someone will find this information useful.

Happy coding.

Answer 2

For Netbeans 11 users, this works for me:

apply plugin: 'java'
apply plugin: 'application'

// This comes out to package + '.' + mainClassName
mainClassName = 'com.hello.JavaApplication1'

Here generally is my tree:

C:\...\NETBEANSPROJECTS\JAVAAPPLICATION1
│   build.gradle
├───src
│   ├───main
│   │   └───java
│   │       └───com
│   │           └───hello
│   │                   JavaApplication1.java
│   │
│   └───test
│       └───java
└───test

Answer 3

1. verify if gradle.properties define right one JAVA_HOVE

   org.gradle.java.home=C:\Program Files (x86)\Java\jdk1.8.0_181

or

2. if it's not defined be sure if Eclipse know JDK and not JRE

Answer 4

I resolved it by adding below code to my application.

// enter code here this is error I was getting when I run build.gradle. main class name has not been configured and it could not be resolved

public static void main(String[] args) {
    SpringApplication.run(Application.class, args);
}

Answer 5

If you decided to write your hello.World class in Kotlin, another issue might be that you have to reference it as mainClassName = "hello.WorldKt".

src/main/java/hello/World.kt:

package hello
fun main(args: Array<String>) {
    ...
}
// class World {} // this line is not necessary

Answer 6

Just to make it clear for newbies trying to run a gradle project from Netbeans:
To understand this, you need to see what the main class name looks like and what the gradle build looks like:

Main class:

package com.stormtrident;

public class StormTrident {
    public static void main(String[] cmdArgs) {
    }
}

Notice that it is part of the package "com.stormtrident".

Gradle build:

apply plugin: 'java'

defaultTasks 'jar'

jar {
 from {
        (configurations.runtime).collect {
            it.isDirectory() ? it : zipTree(it)
        }
    }    
    manifest {
        attributes 'Main-Class': 'com.stormtrident.StormTrident'
    }
}


sourceCompatibility = '1.8'
[compileJava, compileTestJava]*.options*.encoding = 'UTF-8'

if (!hasProperty('mainClass')) {
    ext.mainClass = 'com.stormtrident.StormTrident'
}

repositories {
    mavenCentral()
}

dependencies {
    //---apache storm
    compile 'org.apache.storm:storm-core:1.0.0'  //compile 
    testCompile group: 'junit', name: 'junit', version: '4.10'
}