Eclipse throws NullPointerException during Maven update

问题

I've been fighting an internal Eclipse error for two days. I'm running the latest Spring Tool Suite edition of Eclipse, and I've attempting to import a collection of existing Maven projects. Whenever I do so, Eclipse throws a NullPointerException, but no stack trace is available from the Error Log view. If I instruct Eclipse to update the Maven project (Maven > Update Project), I get a NullPointerException again. This time, the Error Log view reports the following stack trace:

java.lang.NullPointerException
    at org.eclipse.wst.common.componentcore.internal.resources.VirtualResource.getProjectRelativePaths(VirtualResource.java:119)
    at org.eclipse.wst.common.componentcore.internal.resources.VirtualFile.getUnderlyingFiles(VirtualFile.java:104)
    at org.eclipse.wst.common.componentcore.internal.resources.VirtualFile.getUnderlyingResources(VirtualFile.java:93)
    at org.eclipse.wst.common.componentcore.internal.resources.VirtualResource.exists(VirtualResource.java:88)
    at org.eclipse.jst.common.internal.modulecore.util.ManifestUtilities.getNonBinaryComponentManifest(ManifestUtilities.java:124)
    at org.eclipse.jst.common.internal.modulecore.util.ManifestUtilities.getManifest(ManifestUtilities.java:81)
    at org.eclipse.jst.common.internal.modulecore.util.ManifestUtilities.getManifestClasspath(ManifestUtilities.java:147)
    at org.eclipse.jst.j2ee.componentcore.J2EEModuleVirtualComponent.getManifestClasspath(J2EEModuleVirtualComponent.java:248)
    at org.eclipse.jst.j2ee.componentcore.J2EEModuleVirtualComponent.calculateManifestReferences(J2EEModuleVirtualComponent.java:368)
    at org.eclipse.jst.j2ee.componentcore.J2EEModuleVirtualComponent.cacheManifestReferences(J2EEModuleVirtualComponent.java:360)
    at org.eclipse.jst.j2ee.componentcore.J2EEModuleVirtualComponent.getReferences(J2EEModuleVirtualComponent.java:176)
    at org.eclipse.jst.j2ee.componentcore.J2EEModuleVirtualComponent.getReferences(J2EEModuleVirtualComponent.java:214)
    at org.eclipse.jst.j2ee.componentcore.J2EEModuleVirtualComponent.getReferences(J2EEModuleVirtualComponent.java:207)
    at org.eclipse.m2e.wtp.WebProjectConfiguratorDelegate.configureClasspath(WebProjectConfiguratorDelegate.java:386)
    at org.eclipse.m2e.wtp.WTPProjectConfigurator.configureClasspath(WTPProjectConfigurator.java:107)
    at org.eclipse.m2e.jdt.internal.DefaultClasspathManagerDelegate.populateClasspath(DefaultClasspathManagerDelegate.java:61)
    at org.eclipse.m2e.jdt.internal.BuildPathManager.getClasspath(BuildPathManager.java:253)
    at org.eclipse.m2e.jdt.internal.BuildPathManager.getClasspath(BuildPathManager.java:363)
    at org.eclipse.m2e.jdt.internal.BuildPathManager.getClasspath(BuildPathManager.java:343)
    at org.eclipse.m2e.jdt.internal.BuildPathManager.getClasspath(BuildPathManager.java:371)
    at org.eclipse.m2e.jdt.internal.BuildPathManager.updateClasspath(BuildPathManager.java:191)
    at org.eclipse.m2e.jdt.internal.BuildPathManager.mavenProjectChanged(BuildPathManager.java:180)
    at org.eclipse.m2e.core.internal.project.registry.ProjectRegistryManager.notifyProjectChangeListeners(ProjectRegistryManager.java:746)
    at org.eclipse.m2e.core.internal.project.registry.ProjectRegistryManager.applyMutableProjectRegistry(ProjectRegistryManager.java:865)
    at org.eclipse.m2e.core.internal.project.registry.ProjectRegistryManager.refresh(ProjectRegistryManager.java:289)
    at org.eclipse.m2e.core.internal.project.ProjectConfigurationManager.updateProjectConfiguration0(ProjectConfigurationManager.java:369)
    at org.eclipse.m2e.core.internal.project.ProjectConfigurationManager$2.call(ProjectConfigurationManager.java:316)
    at org.eclipse.m2e.core.internal.project.ProjectConfigurationManager$2.call(ProjectConfigurationManager.java:1)
    at org.eclipse.m2e.core.internal.embedder.MavenExecutionContext.executeBare(MavenExecutionContext.java:161)
    at org.eclipse.m2e.core.internal.embedder.MavenExecutionContext.execute(MavenExecutionContext.java:137)
    at org.eclipse.m2e.core.internal.embedder.MavenExecutionContext.execute(MavenExecutionContext.java:89)
    at org.eclipse.m2e.core.internal.embedder.MavenImpl.execute(MavenImpl.java:1301)
    at org.eclipse.m2e.core.internal.project.ProjectConfigurationManager.updateProjectConfiguration(ProjectConfigurationManager.java:313)
    at org.eclipse.m2e.core.ui.internal.UpdateMavenProjectJob.runInWorkspace(UpdateMavenProjectJob.java:77)
    at org.eclipse.core.internal.resources.InternalWorkspaceJob.run(InternalWorkspaceJob.java:38)
    at org.eclipse.core.internal.jobs.Worker.run(Worker.java:53)

Here's what I've tried:

I've blown away my workspace and created a new one. Multiple times.
I've blown away my Maven repository so that it would be re-created.
I've reinstalled Spring Tool Suite.
I've tried asking Eclipse to update the Maven repositories.
I've checked for merge conflicts in my local SVN repository. (There are none; this is a brand new branch from trunk that is freshly checked out.)
I've checked the Synchronize view in Eclipse to see if it notes any differences. (Eclipse can't get far enough to recognize any projects available to synchronize.)
I've searched Google for NullPointerExceptions occurring in VirtualResource.getProjectRelativePaths(). I've found NullPointerExceptions in other very similar places, and I've tried the recommendations for them, just for the heck of it, but none of them work.

I'm at my wits' end with this problem. Help me, Obi-Wan Kenobi, you are my only hope.

回答1:

I'm strongly sure that the problem is not related to the maven plugin; but if it is, i was wandering if you run a mvn eclipse:eclipse before importing the project into eclipse, if you do that and you are using maven 3, I had checked that maven plugin does not support maven 3 properly yet; so I encourage you to make a mvn eclipse:clean, then import the project as an existing project, and after that activate the maven plugin nature from eclipse. I hope it helps,

PS. it seems to be a know eclipse bug (https://www.google.com.uy/search?q=j2ee.componentcore.J2EEModuleVirtualComponent.getReferences(J2EEModuleVirtualComponent.java&oq=j2ee.componentcore.J2EEModuleVirtualComponent.getReferences(J2EEModuleVirtualComponent.java&aqs=chrome..69i57.128j0j7&sourceid=chrome&espv=210&es_sm=91&ie=UTF-8); try downloading the last eclipse version; I'm using kepler at work, and I'm working in maven/spring projects and it works fine.

Good luck!

回答2:

This is what I did to fix it:

Removed the project from the workspace
Remove .classpath, .project and .settings folder
Reimport the project

回答3:

As echinelli indicated, this did turn out to be an Eclipse (or STS) bug, but installing the latest version isn't the fix, as I already had that version installed. I had installed STS based on Eclipse 4.x; when I uninstalled that and went to the 3.x version, the problem went away.

回答4:

This happens because your m2e plugins are corrupted. To rectify follow the steps below.

close eclipse
Go to your eclipse workspace folder Under .metadata/pluigns folder, identify all m2e plugins
delete them
copy the relevant plugins from non-corrupted workspace, either from your machine or from any one of your team members machine
restart eclipse

回答5:

Ok, I had the same issue with a more obscure reason.

I used pluginExecution for aspectj-maven-plugin and over the course of trying to fix yet another maven issue I had commented out <action><execute><execute></action>

This leads to the nullpointerexception.

回答6:

I solved by adding the <build> section with "maven-compiler-plugin" artifact in the POM. I noticed that without it, Eclipse threw a java.lang.NullPointerException.

来源：https://stackoverflow.com/questions/19779141/eclipse-throws-nullpointerexception-during-maven-update

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java

eclipse

maven

spring-tool-suite