Null Pointer Exception when mirrorOf missing from mirror in settings.xml

• Complexity:

  Intermediate

When attempting to generate any archetype from the mvn archetype:generate command I get a null pointer exception thrown if I have mirrors defined in my settings.xml file but fail to have the mirrorOf element set.

The stack trace for the archetype generation is:

Choose a number: (1/2/3/4/5/6/7/8/9/10/11/12/13/14/15/16/17/18/19/20/21/22/23/2
4/25/26/27/28/29/30/31/32/33/34/35/36/37/38/39/40/41/42/43/44) 15: : 6
[INFO] ------------------------------------------------------------------------
[ERROR] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] : java.lang.NullPointerException
null
[INFO] ------------------------------------------------------------------------
[INFO] Trace
org.apache.maven.BuildFailureException
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoals(Defa
ultLifecycleExecutor.java:579)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeStandalone
Goal(DefaultLifecycleExecutor.java:512)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoal(Defau
ltLifecycleExecutor.java:482)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalAndHan
dleFailures(DefaultLifecycleExecutor.java:330)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeTaskSegmen
ts(DefaultLifecycleExecutor.java:227)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.execute(DefaultLi
fecycleExecutor.java:142)
at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:336)
at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:129)
at org.apache.maven.cli.MavenCli.main(MavenCli.java:287)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.
java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAcces
sorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.codehaus.classworlds.Launcher.launchEnhanced(Launcher.java:315)
at org.codehaus.classworlds.Launcher.launch(Launcher.java:255)
at org.codehaus.classworlds.Launcher.mainWithExitCode(Launcher.java:430)

at org.codehaus.classworlds.Launcher.main(Launcher.java:375)
Caused by: org.apache.maven.plugin.MojoFailureException
at org.apache.maven.archetype.mojos.CreateProjectFromArchetypeMojo.execu
te(CreateProjectFromArchetypeMojo.java:202)
at org.apache.maven.plugin.DefaultPluginManager.executeMojo(DefaultPlugi
nManager.java:451)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoals(Defa
ultLifecycleExecutor.java:558)
... 16 more
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 7 seconds
[INFO] Finished at: Wed May 28 17:49:39 EST 2008
[INFO] Final Memory: 8M/14M
[INFO] ------------------------------------------------------------------------

C:\Documents and Settings\frank\My Documents\Development\Sandbox>mvn -v
Maven version: 2.0.9
Java version: 1.5.0_08
OS name: "windows xp" version: "5.1" arch: "x86" Family: "windows"

The mirrored settings from the settings.xml file are:

<mirrors>
<mirror>
<id>nexus-central</id>
<url>http://maven.ho.bushlife.com.au:8081/nexus/content/groups/public</url>
</mirror>
</mirrors>

As a user you receive a null pointer exception because of something missing in the settings.xml file.

At the very least you should receive an error message indicating the problem. If you can have a situation where the mirrorOf setting is optional, then it should not be throwing a null pointer exception but handling it better.