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

User · Answer

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 lt String gt                  class World       this line is not necessary

User · Answer

When I had this error  it was because I didn t have my class in a package  Put your HelloWorld java file in a  package  folder  You may have to create a new package folder   Right click on the hello folder and select  New     Package   Then give it a name  e g  com example  and move your HelloWorld java class into the package

User · Answer

verify if gradle properties define right one JAVA HOVE  org gradle java home C  Program Files  x86  Java jdk1 8 0 181   or    if it s not defined be sure if Eclipse know JDK and not JRE

User · Answer

If you re using Spring Boot  this might be the issue  https   github com gradle gradle issues 2489  Basically  the output directories changed in Gradle 4 0  so if you have them hardcoded the execution will fail  The solution is to replace  bootRun      dependsOn pathingJar    doFirst         classpath   files  quot  buildDir classes main quot    quot  buildDir resources main quot   pathingJar archivePath          by  bootRun      dependsOn pathingJar    doFirst         classpath   files sourceSets main output files  pathingJar archivePath

User · Answer

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

User · Answer

Struggled with the same problem for some time  But after creating the directory structure src main java and putting the source from the top of the package   it worked as expected   The tutorial I tried with  After you execute gradle build  you will have to be able to find classes under build directory

User · Answer

For a project structure like  project name src main java Main File class   in the file build gradle  add the following line  mainClassName    Main File

User · Answer

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

User · Answer

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

User · Answer

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

User · Answer

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

User · Answer

I fixed this by running a clean of by gradle build  or delete the gradle build folder mannually   This occurs if you move the main class to a new package and the old main class is still referenced in the claspath

User · Answer

I see two problems here  one with sourceSet another with mainClassName    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    mainClassName should be fully qualified class name  not path   mainClassName    hello HelloWorld

User · Answer

In my build gradle  I resolved this issue by creating a task and then specifying the  mainClassName  as follows   task runSimpleXYZProgram  group   algorithms   description   Description of what your program does   dependsOn   classes   type  JavaExec        mainClassName    your entire package classContainingYourMainMethod

[java] Gradle - Could not find or load main class

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