Error running project in eclipse wtih maven "Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.1:compile"

Question

I'm learning google app engine programs with eclipse and maven but I've been stuck on this error since 2 days. I've looked everywhere on the internet but couldn't get a solution to my problem.

Here's the console output

[INFO] Scanning for projects...
[INFO]                                                                         
[INFO] ------------------------------------------------------------------------
[INFO] Building helloworld 1.0-SNAPSHOT
[INFO] ------------------------------------------------------------------------
[INFO] 
[INFO] >>> appengine-maven-plugin:1.9.4:devserver (default-cli) > package @ helloworld >>>
[INFO] 
[INFO] --- maven-resources-plugin:2.6:resources (default-resources) @ helloworld ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] skip non existing resourceDirectory /Users/AdioJack/Developer/Scalable Apps (Udacity)/ud859-master/Lesson_2/000_Hello_Endpoints/src/main/resources
[INFO] 
[INFO] --- maven-compiler-plugin:3.1:compile (default-compile) @ helloworld ---
[INFO] Changes detected - recompiling the module!
[INFO] Compiling 3 source files to /Users/AdioJack/Developer/Scalable Apps (Udacity)/ud859-master/Lesson_2/000_Hello_Endpoints/target/helloworld-1.0-SNAPSHOT/WEB-INF/classes
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 2.462 s
[INFO] Finished at: 2014-09-10T12:34:38+05:30
[INFO] Final Memory: 6M/81M
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.1:compile (default-compile) on project helloworld: Fatal error compiling: invalid target release: 1.7 -> [Help 1]
[ERROR] 
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR] 
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoExecutionException

and here's the 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>
    <packaging>war</packaging>
    <version>1.0-SNAPSHOT</version>

    <groupId>com.google.training.helloworld</groupId>
    <artifactId>helloworld</artifactId>

    <properties>
        <appengine.app.version>1</appengine.app.version>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <prerequisites>
        <maven>3.1.0</maven>
    </prerequisites>

    <dependencies>
        <!-- Compile/runtime dependencies -->
        <dependency>
            <groupId>com.google.appengine</groupId>
            <artifactId>appengine-api-1.0-sdk</artifactId>
            <version>1.9.4</version>
        </dependency>
        <dependency>
            <groupId>com.google.appengine</groupId>
            <artifactId>appengine-endpoints</artifactId>
            <version>1.9.4</version>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>servlet-api</artifactId>
            <version>2.5</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>javax.inject</groupId>
            <artifactId>javax.inject</artifactId>
            <version>1</version>
        </dependency>

        <!-- Test Dependencies -->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.11</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>com.google.appengine</groupId>
            <artifactId>appengine-testing</artifactId>
            <version>1.9.4</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>com.google.appengine</groupId>
            <artifactId>appengine-api-stubs</artifactId>
            <version>1.9.4</version>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <!-- for hot reload of the web application-->
        <outputDirectory>${project.build.directory}/${project.build.finalName}/WEB-INF/classes</outputDirectory>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <version>3.1</version>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>1.7</source>
                    <target>1.7</target>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-war-plugin</artifactId>
                <version>2.4</version>
                <configuration>
                    <webXml>${project.build.directory}/generated-sources/appengine-endpoints/WEB-INF/web.xml</webXml>
                    <webResources>
                        <resource>
                            <!-- this is relative to the pom.xml directory -->
                            <directory>${project.build.directory}/generated-sources/appengine-endpoints</directory>
                            <!-- the list has a default value of ** -->
                            <includes>
                                <include>WEB-INF/*.discovery</include>
                                <include>WEB-INF/*.api</include>
                            </includes>
                        </resource>
                    </webResources>
                </configuration>
            </plugin>
            <plugin>
                <groupId>com.google.appengine</groupId>
                <artifactId>appengine-maven-plugin</artifactId>
                <version>1.9.4</version>
                <configuration>
                    <enableJarClasses>false</enableJarClasses>
                    <!-- Comment in the below snippet to bind to all IPs instead of just localhost -->
                    <!-- address>0.0.0.0</address>
                    <port>8080</port -->
                    <!-- Comment in the below snippet to enable local debugging with a remove debugger
                         like those included with Eclipse or IntelliJ -->
                    <!-- jvmFlags>
                      <jvmFlag>-agentlib:jdwp=transport=dt_socket,address=8000,server=y,suspend=n</jvmFlag>
                    </jvmFlags -->
                </configuration>                
                <executions>
                    <execution>
                        <goals>
                            <goal>endpoints_get_discovery_doc</goal>
                        </goals>
                    </execution>
                </executions>

            </plugin>
        </plugins>
    </build>

</project>

Here's java & maven version information

Apache Maven 3.2.3 (33f8c3e1027c3ddde99d3cdebad2656a31e8fdf4; 2014-08-12T02:28:10+05:30)
Maven home: /usr/local/Cellar/maven/3.2.3/libexec
Java version: 1.8.0_20, vendor: Oracle Corporation
Java home: /Library/Java/JavaVirtualMachines/jdk1.8.0_20.jdk/Contents/Home/jre
Default locale: en_US, platform encoding: UTF-8
OS name: "mac os x", version: "10.10", arch: "x86_64", family: "mac"

This question is different from How to set specific java version to Maven

I've only 1 version of java installed i.e. JDK 8

This is the command I ran in terminal to make maven is using latest java version

export JAVA_HOME=$(/usr/libexec/java_home)

Answer 1

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.1:compile (default-compile) on project helloworld: Fatal error compiling: invalid target release: 1.7 -> [Help 1]

If you look at the error, its complaining about an JDK7. Make sure you are using correct version of Java to be able to compile the application. You need atleast jdk1.7 (or higher).

As the question is tagged for eclipse, you can also set the available java compilers in the 'installeded JREs' option inside eclipse

Apart from that, you can also set the compliance level inside the pom of the project as below

        <plugin>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>3.1</version>
            <configuration>
                <source>1.7</source> <!-- or 1.8 -->
                <target>1.7</target> <!-- or 1.8 -->
            </configuration>
        </plugin>

Answer 2

You have to install java 7 for the compile to work, however, java 8 and newer should also work