How to fix [Error] realm = plugin>org.apache.maven.plugins:maven-compiler-plugin:3.x (Happened while working on Spring Boot)

Question

Problem

I decided to get spring boot hello word example to work with Java 1.8 but an annoying dependency issues. In the answer section I explain what solved my problem as well as some hints on how to bring everything on your machine up to date. The error I was getting was:

[ERROR] realm =    plugin>org.apache.maven.plugins:maven-compiler-plugin:3.x
[ERROR] strategy = org.codehaus.plexus.classworlds.strategy.SelfFirstStrategy
[ERROR] urls[0] = file:/Users/xxx/.m2/repository/org/apache/maven/plugins/maven-compiler-plugin/3.1/maven-compiler-plugin-3.1.jar
[ERROR] urls[1] = file:/Users/xxx/.m2/repository/org/codehaus/plexus/plexus-utils/1.5.1/plexus-utils-1.5.1.jar
[ERROR] urls[2] = file:/Users/xxx/repository/org/apache/maven/shared/maven-shared-utils/0.1/maven-shared-utils-0.1.jar
[ERROR] urls[3] = file:/Users/xxx/repository/com/google/code/findbugs/jsr305/2.0.1/jsr305-2.0.1.jar
[ERROR] urls[4] = file:/Users/xxx/.m2/repository/org/apache/maven/shared/maven-shared-incremental/1.1/maven-shared-incremental-1.1.jar
[ERROR] urls[5] = file:/Users/xxx/.m2/repository/org/codehaus/plexus/plexus-component-annotations/1.5.5/plexus-component-annotations-1.5.5.jar
[ERROR] urls[6] = file:/Users/xxx/.m2/repository/org/codehaus/plexus/plexus-compiler-api/2.2/plexus-compiler-api-2.2.jar
[ERROR] urls[7] = file:/Users/xxx/.m2/repository/org/codehaus/plexus/plexus-compiler-manager/2.2/plexus-compiler-manager-2.2.jar
[ERROR] urls[8] = file:/Users/xxx/.m2/repository/org/codehaus/plexus/plexus-compiler-javac/2.2/plexus-compiler-javac-2.2.jar
[ERROR] urls[9] = file:/Users/xxx/.m2/repository/org/apache/xbean/xbean-reflect/3.4/xbean-reflect-3.4.jar
[ERROR] urls[10] = file:/Users/xxx/.m2/repository/log4j/log4j/1.2.12/log4j-1.2.12.jar
[ERROR] urls[11] = file:/Users/xxx/.m2/repository/commons-logging/commons-logging-api/1.1/commons-logging-api-1.1.jar
[ERROR] urls[12] = file:/Users/xxx/.m2/repository/com/google/collections/google-collections/1.0/google-collections-1.0.jar
[ERROR] urls[13] = file:/Users/xxx/.m2/repository/junit/junit/3.8.2/junit-3.8.2.jar

---

Solutions that didn't work

A lot of the threads were suggesting removing the ~/.m2/ repositories like here but it did not solve my problem.

Some others said that this is due to the Java 1.8 and it works perfectly for them with Java 1.7! But couldn't believe them as it did not make sense. And I really wanted to get this simple example to work with Java 8.

Solution summary

It was a dependency conflict but had nothing to do with the Java version or the repositories under .m2 folder for me.

The source of the error was a dependency conflict that was caused plugin>org.apache.maven.plugins:maven-compiler-plugin:3.x.

---

Other related sources

Other questions on stackoverflow that are similar but didn't solve my problem with spring boot are as follows:

1- maven-build-error-failed-to-execute-goal-missing-a-class

2- failed-to-execute-goal-org-apache-maven-pluginsmaven-compiler-plugin2-3-2comp

3- maven-release-plugin-issue-failed-to-execute-goal-org-apache-maven-pluginsmav

4- maven-archetype-problem

Answer 1

Solution

As I mentioned, the source of the error was a dependency conflict that was caused plugin>org.apache.maven.plugins:maven-compiler-plugin:3.x. Based on the comment made in some cases specifying the Java version through <properties><java.version>1.8</java.version></properties> solves their problem for some (based on the guide here).

However in my case (checkout the specs) only specifying the maven compiler plugin and through the following code solved my problem:

<plugin>
    <artifactId>maven-compiler-plugin</artifactId>
    <version>2.3.2</version>
    <configuration>
        <source>1.8</source>
        <target>1.8</target>
    </configuration>
</plugin>

Specs

• Java 1.8_45
• Maven 3.3.3
• OS X Yosemite

Files

Basically I had to specify the maven-compiler-plugin in my pom.xml (see below).

POM.XML

<?xml version="1.0" encoding="UTF-8"?>
<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/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>


    <groupId>com.mycompany</groupId>
    <artifactId>helloworld</artifactId>
    <version>0.1.0</version>
    <!-- Inherit defaults from Spring Boot -->
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.2.2.RELEASE</version>
    </parent>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

    </dependencies>
    <build>
        <plugins>

            <plugin>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>2.3.2</version>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>

        </plugins>
    </build>
</project>

SampleContoroller.java

import org.springframework.boot.*;
import org.springframework.boot.autoconfigure.*;
import org.springframework.web.bind.annotation.*;

@RestController
@EnableAutoConfiguration
public class SampleController {

    @RequestMapping("/")
    String home() {
        return "Hello World!";
    }

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

Project folder structure

Just follow maven standard structure.

Hint Please feel free to give me feedback in the comments if this solved your problem, or if you faced other issues.