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Editorial Team
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Asked: 2026-06-16T09:55:58+00:00

I’ve been developing in Java using maven for a few days now. Today I

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I’ve been developing in Java using maven for a few days now. Today I edited my pom.xml based on these instructions. Suddenly running mvn compile is giving me errors as if I was compiling with an older version of java. Stuff like:

error: generics are not supported in -source 1.3

Now I’ve paired my pom.xml back to its original content, and I’m still getting this error. I’ve done a mvn clean and deleted everything under target, and am still having this problem.

Here’s a snippet of maven running the compilation phase:

[INFO] Scanning for projects...
[INFO]                                                                         
[INFO] ------------------------------------------------------------------------
[INFO] Building bahToBeh 1.0-SNAPSHOT
[INFO] ------------------------------------------------------------------------
[INFO] 
[INFO] --- maven-resources-plugin:2.3:resources (default-resources) @ bahToBeh ---
[WARNING] Using platform encoding (UTF-8 actually) to copy filtered resources, i.e. build is platform dependent!
[INFO] skip non existing resourceDirectory /home/doug/lucid/bah-bio-demo/bahToBeh/src/main/resources
[INFO] 
[INFO] --- maven-compiler-plugin:2.0.2:compile (default-compile) @ bahToBeh ---
[INFO] Compiling 9 source files to /home/doug/lucid/bah-bio-demo/bahToBeh/target/classes
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 2.880s
[INFO] Finished at: Thu Dec 20 13:52:06 EST 2012
[INFO] Final Memory: 7M/105M
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:2.0.2:compile (default-compile) on project bahToBeh: Compilation failure: Compilation failure:
[ERROR] /home/doug/lucid/bah-bio-demo/bahToBeh/src/main/java/com/lucid/bahdemo/parsers/pm/MeshReader.java:[23,4] error: generics are not supported in -source 1.3

And my paired-down 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.lucid</groupId>
  <artifactId>bahToBeh</artifactId>
  <packaging>jar</packaging>
  <version>1.0-SNAPSHOT</version>
  <name>bahToBeh</name>
  <url>http://maven.apache.org</url>
  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.8.1</version>
      <scope>test</scope>
  </dependency>
    <dependency>
      <groupId>com.digitalpebble</groupId>
      <artifactId>behemoth-core</artifactId>
      <version>1.0</version>
  </dependency>
  <dependency>
      <groupId>org.apache.hadoop</groupId>
      <artifactId>hadoop-core</artifactId>
      <version>1.0.4</version>
  </dependency>
  <dependency>
      <groupId>marc4j</groupId>
      <artifactId>marc4j</artifactId>
      <version>2.4</version>
  </dependency>
  </dependencies>
</project>

This had been working fine up until today. I’m not sure what setting I might have changed or how I could have munged up my project. I even double checked that the correct versions of java are installed:

doug@doug-VirtualBox:~/lucid/bah-bio-demo/bahToBeh$ java -version
java version "1.7.0_10"
Java(TM) SE Runtime Environment (build 1.7.0_10-b18)
Java HotSpot(TM) 64-Bit Server VM (build 23.6-b04, mixed mode)
doug@doug-VirtualBox:~/lucid/bah-bio-demo/bahToBeh$ javac -version
javac 1.7.0_10

Here is JAVA_HOME

doug@doug-VirtualBox:~/lucid/bah-bio-demo/bahToBeh$ echo $JAVA_HOME
/usr/lib/jvm/java-7-oracle

Maven IS using the pom.xml I think it is, if I run mvn -X compile I get:

DEBUG] (f) project = MavenProject: com.lucid:bahToBeh:1.0-SNAPSHOT @ /home/doug/lucid/bah-bio-demo/bahToBeh/pom.xml

I’ve also deleted my maven repo rm -rf ~/.m2 and saw maven redownload everything same problem.

EDIT — It suddenly works mysteriously
I have no idea what happened, but suddenly now its working. I thought that one thing I changed was I commented out a test. I went and uncommented out the test and then ran mvn compile and this time it compiled. Some state somewhere was out-of-sync and now things magically work?

I hate not knowing why my tools suddenly go wonky, so this is not an answer to the question, merely more information.

EDIT — and it also just suddenly STOPPED working again
Looks like fully specifying the version to compile works though, so dingding thats the winner.

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1 Answer

  1. Editorial Team

    Set the source and target java versions explicitly. http://maven.apache.org/plugins/maven-compiler-plugin/examples/set-compiler-source-and-target.html

    <project>
  [...]
  <build>
    [...]
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>3.0</version>
        <configuration>
          <source>1.7</source>
          <target>1.7</target>
        </configuration>
      </plugin>
    </plugins>
    [...]
  </build>
  [...]
</project>
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