空指针异常：在e4中注入eclipse服务时发生。

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英文:

NullPointer when Injecting eclipse Services in e4

问题

快速版本，供急于求解的读者参考：

在启动Eclipse RCP应用程序时，插件中的一个部分抛出了NullPointerException，因为以下代码似乎无法正常工作，partService 似乎为null：

	@Inject
	EPartService partService;

一些背景信息：

我必须为一个相当混乱的RCP应用程序实现一些功能。有几个插件，大多数创建一些UI部分。

在其中一个部分中，使用EPartService来对部分的激活做出反应，并处理来自其他部分的数据。

在createComposite 方法中调用 partService.addPartListener( 的时候，异常被抛出（见下文）

我之前所做的是将整个代码从分布在几个Git仓库中的代码整合到一个仓库中。

此外，我似乎在这个部分缺少了对javax.inject.Inject的依赖，我通过手动将jar文件添加到这个插件中来进行了一些“修复”。

此外，我非常确定上一个编译和发布此应用程序的人是使用较旧版本的Eclipse（我正在使用jee-2020-06）。

有没有人能够识别这个错误并为解决方向提出建议？我找到的与这个错误有关的引用似乎来自2009年左右，并且与某个框架补丁有关，这是我没有进行过的（我想）。

异常信息：

org.eclipse.e4.core.di.InjectionException: java.lang.NullPointerException
	...
Caused by: java.lang.NullPointerException
	...

请注意，上述文本是对原文的翻译，可能因语言差异而导致某些技术术语的不准确翻译。如有需要，请根据上下文进行调整。

英文:

Quick version for the impatient:

When starting an Eclipse RCP Application a Part in a plug-in throws a NullPointerException because the following lines did not seem to work, as partService seems to be null

	@Inject
	EPartService partService;

Some context:

I have to implement some features for a rather messy RCP Application. There are several plug-ins, mostly creating some UI parts.

In one of the Parts, the EPartService is used to react to the activation of the part and do some stuff with data from other parts.

The moment partService.addPartListener( is called within the createComposite method, the Exception is thrown (see below)

What I had to do beforehand, was take the whole code, which was separated over several git-repos, and unite it in one repo.

I also seemed to have a missing dependency for javax.inject.Inject in this very Part which I somehow "fixed" by manually adding the jar to this plug-in.

Furthermore, I am pretty sure the last person to compile and release this application was using an older version of eclipse (I am using jee-2020-06)

Does anyone recognize the error and have a suggestion for a direction to look into? The references to this error I found seemed to be from around 2009 and have something to do with a Framework patch, I didn't do (I think).
Exception:

org.eclipse.e4.core.di.InjectionException: java.lang.NullPointerException
	at org.eclipse.e4.core.internal.di.MethodRequestor.execute(MethodRequestor.java:68)
	at org.eclipse.e4.core.internal.di.InjectorImpl.processAnnotated(InjectorImpl.java:999)
	at org.eclipse.e4.core.internal.di.InjectorImpl.internalInject(InjectorImpl.java:140)
	at org.eclipse.e4.core.internal.di.InjectorImpl.internalMake(InjectorImpl.java:405)
	at org.eclipse.e4.core.internal.di.InjectorImpl.make(InjectorImpl.java:332)
	at org.eclipse.e4.core.contexts.ContextInjectionFactory.make(ContextInjectionFactory.java:202)
	at org.eclipse.e4.ui.internal.workbench.ReflectionContributionFactory.createFromBundle(ReflectionContributionFactory.java:91)
	at org.eclipse.e4.ui.internal.workbench.ReflectionContributionFactory.doCreate(ReflectionContributionFactory.java:60)
	at org.eclipse.e4.ui.internal.workbench.ReflectionContributionFactory.create(ReflectionContributionFactory.java:42)
	at org.eclipse.e4.ui.workbench.renderers.swt.ContributedPartRenderer.createWidget(ContributedPartRenderer.java:132)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.createWidget(PartRenderingEngine.java:1000)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.safeCreateGui(PartRenderingEngine.java:660)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.safeCreateGui(PartRenderingEngine.java:766)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.access$0(PartRenderingEngine.java:737)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$2.run(PartRenderingEngine.java:731)
	at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:45)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.createGui(PartRenderingEngine.java:715)
	at org.eclipse.e4.ui.workbench.renderers.swt.StackRenderer.showTab(StackRenderer.java:1294)
	at org.eclipse.e4.ui.workbench.renderers.swt.LazyStackRenderer.postProcess(LazyStackRenderer.java:105)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.safeCreateGui(PartRenderingEngine.java:678)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.safeCreateGui(PartRenderingEngine.java:766)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.access$0(PartRenderingEngine.java:737)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$2.run(PartRenderingEngine.java:731)
	at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:45)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.createGui(PartRenderingEngine.java:715)
	at org.eclipse.e4.ui.workbench.renderers.swt.SWTPartRenderer.processContents(SWTPartRenderer.java:71)
	at org.eclipse.e4.ui.workbench.renderers.swt.SashRenderer.processContents(SashRenderer.java:148)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.safeCreateGui(PartRenderingEngine.java:674)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.safeCreateGui(PartRenderingEngine.java:766)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.access$0(PartRenderingEngine.java:737)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$2.run(PartRenderingEngine.java:731)
	at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:45)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.createGui(PartRenderingEngine.java:715)
	at org.eclipse.e4.ui.workbench.renderers.swt.SWTPartRenderer.processContents(SWTPartRenderer.java:71)
	at org.eclipse.e4.ui.workbench.renderers.swt.SashRenderer.processContents(SashRenderer.java:148)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.safeCreateGui(PartRenderingEngine.java:674)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.safeCreateGui(PartRenderingEngine.java:766)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.access$0(PartRenderingEngine.java:737)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$2.run(PartRenderingEngine.java:731)
	at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:45)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.createGui(PartRenderingEngine.java:715)
	at org.eclipse.e4.ui.workbench.renderers.swt.SWTPartRenderer.processContents(SWTPartRenderer.java:71)
	at org.eclipse.e4.ui.workbench.renderers.swt.PerspectiveRenderer.processContents(PerspectiveRenderer.java:51)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.safeCreateGui(PartRenderingEngine.java:674)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.safeCreateGui(PartRenderingEngine.java:766)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.access$0(PartRenderingEngine.java:737)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$2.run(PartRenderingEngine.java:731)
	at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:45)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.createGui(PartRenderingEngine.java:715)
	at org.eclipse.e4.ui.workbench.renderers.swt.PerspectiveStackRenderer.showTab(PerspectiveStackRenderer.java:82)
	at org.eclipse.e4.ui.workbench.renderers.swt.LazyStackRenderer.postProcess(LazyStackRenderer.java:105)
	at org.eclipse.e4.ui.workbench.renderers.swt.PerspectiveStackRenderer.postProcess(PerspectiveStackRenderer.java:64)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.safeCreateGui(PartRenderingEngine.java:678)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.safeCreateGui(PartRenderingEngine.java:766)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.access$0(PartRenderingEngine.java:737)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$2.run(PartRenderingEngine.java:731)
	at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:45)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.createGui(PartRenderingEngine.java:715)
	at org.eclipse.e4.ui.workbench.renderers.swt.SWTPartRenderer.processContents(SWTPartRenderer.java:71)
	at org.eclipse.e4.ui.workbench.renderers.swt.WBWRenderer.processContents(WBWRenderer.java:666)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.safeCreateGui(PartRenderingEngine.java:674)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.safeCreateGui(PartRenderingEngine.java:766)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.access$0(PartRenderingEngine.java:737)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$2.run(PartRenderingEngine.java:731)
	at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:45)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.createGui(PartRenderingEngine.java:715)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$5.run(PartRenderingEngine.java:1084)
	at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:338)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.run(PartRenderingEngine.java:1047)
	at org.eclipse.e4.ui.internal.workbench.E4Workbench.createAndRunUI(E4Workbench.java:155)
	at org.eclipse.ui.internal.Workbench.lambda$3(Workbench.java:658)
	at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:338)
	at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:557)
	at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:154)
[...]
Caused by: java.lang.NullPointerException
[...]

答案1

得分: 1

在插件中添加一个 JAR 文件并不会修复缺失的 Inject 类，它不会被 Eclipse 识别为正确的 Inject 类。因此，注入不会发生，从而导致 NPE。

你的插件应该在 MANIFEST.MF 文件中使用 Import-Package 来导入 javax.inject 包：

Import-Package: javax.inject;version="1.0.0"

在 MANIFEST.MF/plugin.xml 编辑器中，这将被添加到 'Dependencies' 选项卡的 'Imported Packages' 部分。

英文:

Adding a jar in the plug-in will not fix a missing Inject class correct, it will not be recognized by Eclipse as the correct Inject class. So the injection will not happen giving you the NPE.

Your plug-in should use Import-Package in the MANIFEST.MF for the javax.inject package:

Import-Package: javax.inject;version="1.0.0"

In the MANIFEST.MF/plugin.xml editor this is added on the 'Dependencies' tab in the 'Imported Packages' section

huangapple
  • 本文由 发表于 2020年9月24日 15:39:00
  • 转载请务必保留本文链接：https://go.coder-hub.com/64041637.html
  • dependency-injection
  • eclipse
  • eclipse-plugin
  • eclipse-rcp
  • java
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