Why is eclipse giving me this error? - eclipse

Question

Ok, so I installed this plugin for eclipse. I dragged all the stuff in it's features folder into eclipses, and all the stuff from it's plugin folder to eclipse's plugin folder. I also copied the site.xml into eclipse's main folder. But when I started eclipse and tried to view class files, they gave me a eclipse error. I tried uninstalling it, but it didn't show it was installed. I also tried removing the base files I copied, but it still gave me the same error.
The error, up close, is this:
org.eclipse.core.runtime.CoreException: The Class File Viewer cannot handle the given input ('org.eclipse.ui.ide.FileStoreEditorInput').
at org.eclipse.jdt.internal.ui.javaeditor.ClassFileEditor.doSetInput(ClassFileEditor.java:652)
at org.eclipse.ui.texteditor.AbstractTextEditor$19.run(AbstractTextEditor.java:3200)
at org.eclipse.jface.operation.ModalContext.runInCurrentThread(ModalContext.java:464)
at org.eclipse.jface.operation.ModalContext.run(ModalContext.java:372)
at org.eclipse.jface.window.ApplicationWindow$1.run(ApplicationWindow.java:759)
at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:70)
at org.eclipse.jface.window.ApplicationWindow.run(ApplicationWindow.java:756)
at org.eclipse.ui.internal.WorkbenchWindow.run(WorkbenchWindow.java:2649)
at org.eclipse.ui.texteditor.AbstractTextEditor.internalInit(AbstractTextEditor.java:3218)
at org.eclipse.ui.texteditor.AbstractTextEditor.init(AbstractTextEditor.java:3245)
at org.eclipse.ui.internal.EditorManager.createSite(EditorManager.java:828)
at org.eclipse.ui.internal.EditorReference.createPartHelper(EditorReference.java:647)
at org.eclipse.ui.internal.EditorReference.createPart(EditorReference.java:465)
at org.eclipse.ui.internal.WorkbenchPartReference.getPart(WorkbenchPartReference.java:595)
at org.eclipse.ui.internal.EditorAreaHelper.setVisibleEditor(EditorAreaHelper.java:271)
at org.eclipse.ui.internal.EditorManager.setVisibleEditor(EditorManager.java:1459)
at org.eclipse.ui.internal.EditorManager$5.runWithException(EditorManager.java:972)
at org.eclipse.ui.internal.StartupThreading$StartupRunnable.run(StartupThreading.java:31)
at org.eclipse.swt.widgets.RunnableLock.run(RunnableLock.java:35)
at org.eclipse.swt.widgets.Synchronizer.runAsyncMessages(Synchronizer.java:135)
at org.eclipse.swt.widgets.Display.runAsyncMessages(Display.java:4140)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3757)
at org.eclipse.ui.application.WorkbenchAdvisor.openWindows(WorkbenchAdvisor.java:803)
at org.eclipse.ui.internal.Workbench$33.runWithException(Workbench.java:1600)
at org.eclipse.ui.internal.StartupThreading$StartupRunnable.run(StartupThreading.java:31)
at org.eclipse.swt.widgets.RunnableLock.run(RunnableLock.java:35)
at org.eclipse.swt.widgets.Synchronizer.runAsyncMessages(Synchronizer.java:135)
at org.eclipse.swt.widgets.Display.runAsyncMessages(Display.java:4140)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3757)
at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2609)
at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2499)
at org.eclipse.ui.internal.Workbench$7.run(Workbench.java:679)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:668)
at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)
at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:123)
at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:196)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:110)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:79)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:344)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:179)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:622)
at org.eclipse.equinox.launcher.Main.basicRun(Main.java:577)
at org.eclipse.equinox.launcher.Main.run(Main.java:1410)
And a screenshot of the screen is this:

Answer 1

You have not installed the plugin the proper way, it most likely will not work. JD-Eclipse page tells you how to install it correctly. Even if you download archived Update Site, you must use the Install New Software... dialog. The only thing you should do differently in given instructions is in New Repository dialog instead of pasting the Update Site URL into an input - click Archive... button and select zip file you downloaded.
You should not have broken the whole installation by simply copying the jar files into respective folders, but apparently somehow it was corrupted or some bug exposed which threw the given Exception. Exception, actually, looks like it is the Standart JDT Class Editor which failed not the JD-Eclipse.
I suggest you shutdown Eclipse, delete all the files you copy pasted manually, launch it again and try to open some class file in the Workspace. If it works, try to install JD-Eclipse properly (including Microsoft Visual C++ 2008 Express Edition if you are on Windows). If it does not work, try re-installing Eclipse.

Answer 2

What and where you put class files that you want to view ? Are that class file exists in your workspace? If not, try to put your class file in your workspace

Answer 3

For quick and dirty checks, I've found a better option: go to http://jd.benow.ca/ and drag and drop your class file onto the "Live Demo"->"Input Files" section at the bottom. Worked like a charm!