Error: Could not find or load main class [Intellij]

Question

I am struggling to run unit tests or main methods in IntelliJ via the 'Run' button. (Project was set up via maven)

Here is my pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">

  <modelVersion>4.0.0</modelVersion>
  <groupId>com.andrew.app</groupId>
  <artifactId>my-app</artifactId>
  <packaging>jar</packaging>
  <version>1.0-SNAPSHOT</version>
  <name>my-app</name>
  <url>http://maven.apache.org</url>

  <properties>
    <maven.compiler.target>1.8</maven.compiler.target>
    <maven.compiler.source>1.8</maven.compiler.source>
    <java.version>1.8</java.version>
  </properties>

  <build>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>3.6.1</version>
        <configuration>
          <source>1.8</source>
          <target>1.8</target>
        </configuration>
      </plugin>
    </plugins>
  </build>

  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.12</version>
      <scope>test</scope>
    </dependency>
  </dependencies>
</project>

Here is my project directory:

├── my-app.iml
├── pom.xml
├── src
│   ├── main
│   │   └── java
│   │       └── com
│   │           └── andrew
│   │               ├── app
│   │               └── Hello.java
│   └── test
│       └── java
│           └── com
│               └── andrew
│                   ├── app
│                   └── HelloTest.java
└── target
    ├── classes
    │   └── com
    │       └── andrew
    │           └── Hello.class
    ├── generated-sources
    │   └── annotations
    └── maven-status
        └── maven-compiler-plugin
            └── compile
                └── default-compile
                    ├── createdFiles.lst
                    └── inputFiles.lst

I have tried the followings:

Setting Project's compiler output to {project directory}/target
Invalidate cache and restart, rebuild
Running java com.andrew.Hello in ./target/classes returns Hello World
Set ./src/main/java as Source

But I still can't fix the issue.

score 1 · Answer 1 · answered Jun 14 '18 at 14:38

1

Solution

Within Project Structure -> compiler output, I have orignally stated /home/andrew/IdeaProjects/Maven:The-Definitive-Guide/my-app/classes

I have to change it to: /home/andrew/IdeaProjects/Maven_The_Definitive_Guide/my-app/classes

answered Jun 14 '18 at 14:38

creampiedonut

327
1
5
17

Thanks, in my case the output path was wrong, you gave me the right hint. – pikkuez Oct 28 '19 at 15:28

score 0 · Answer 2 · answered Jun 14 '18 at 16:06

You need to make sure of a couple of things here....

Check to make sure all of your test methods are Annotated with {@Test} - see the below image I have added also.

Once they are all annotated you should be able to right click on the file and an option should be to run test, after you do this - the run button automatically adds the latest run configuration to be the last thing you ran, so it should show up there for the Run button

score 0 · Answer 3 · answered Jan 28 '20 at 19:40

0

For my case, I add a Maven run command in IntelliJ Run - Edit Configuration, and set command line parameter as clean install spring-boot:run, it works as run command ./mvnw clean install spring-boot:run in Mac terminal.

answered Jan 28 '20 at 19:40

Yao Li

2,071
1
25
24

Oliver Tazl · Answer 4 · 2018-06-14T13:50:49.580

-1

Right click in the Project View on Hello -> "Run Hello.main()" should work for you.

edited Jun 14 '18 at 13:50

answered Jun 14 '18 at 13:30

Oliver Tazl

54
7

Another possible solution is to add the maven exec plugin to your pom and execute this target https://stackoverflow.com/questions/1089285/maven-run-project https://stackoverflow.com/questions/42540018/run-a-maven-project-using-intellij-idea – Oliver Tazl Jun 14 '18 at 13:35
Yes, that works but is there a way to use the run button in IntelliJ to run the main class? – creampiedonut Jun 14 '18 at 13:41
To run the project with the run button you have either do the right click thing in the first comment or define the maven target "exec:java" as configuration. Once executed the configuration will be stored and the run button should act as desired – Oliver Tazl Jun 14 '18 at 14:01
Let us [continue this discussion in chat](https://chat.stackoverflow.com/rooms/173155/discussion-between-oliver-tazl-and-creampiedonut). – Oliver Tazl Jun 14 '18 at 14:07

Error: Could not find or load main class [Intellij]

4 Answers4