Could not open the editor: The editor class could not be instantiated

Question

some days ago I downloaded the plugin to repackage apk for BlackBerry then I got a message to update the ADT and SDK so I opened the SDK manager and updated all suggested updates. After I restarted I got a message that a certain project cannot be saved but the gui was empty, no project selected. Today I restarted eclipse and get a message "this SDK need an updated ADT 21.0" so I tried to open SDK manager but it said no SDK path has been set. I tried to set The path but it was there already set and no other panel can be opened. I decided to open a manifest from a project and first I got "Could not open the editor: The editor class could not be instantiated. This usually indicates a missing no-arg constructor or that the editor's class name was mistyped in plugin.xml." Then all projects have a red x beside. I'm not able to understand anything about, I wish someone can help me. Thanks. This is in the log file

!SESSION 2013-01-26 22:41:53.953 -----------------------------------------------
eclipse.buildId=M20120208-0800
java.version=1.7.0_11
java.vendor=Oracle Corporation
BootLoader constants: OS=win32, ARCH=x86, WS=win32, NL=it_IT
Framework arguments:  vm C:\Programmi\Java\jdk1.6.0_26\jre\bin\client\jvm.dll
Command-line arguments:  -os win32 -ws win32 -arch x86 vm C:\Programmi\Java\jdk1.6.0_26\jre\bin\client\jvm.dll

This is a continuation of log file C:\Documents and Settings\Angelo Giammarresi\workspace2\.metadata\.bak_0.log
Created Time: 2013-01-26 22:43:47.515

!ENTRY org.eclipse.core.resources 4 1 2013-01-26 22:43:47.515
!MESSAGE Core exception while retrieving the content description
!STACK 1
org.eclipse.core.internal.resources.ResourceException: Resource is out of sync with the file system: '/TitleToolITdemo/AndroidManifest.xml'.
    at org.eclipse.core.internal.resources.File.getContentDescription(File.java:269)
    at org.eclipse.core.internal.propertytester.FilePropertyTester.testContentType(FilePropertyTester.java:108)
    at org.eclipse.core.internal.propertytester.FilePropertyTester.test(FilePropertyTester.java:60)
    at org.eclipse.core.internal.expressions.Property.test(Property.java:58)
    at org.eclipse.core.internal.expressions.TestExpression.evaluate(TestExpression.java:99)
    at org.eclipse.core.internal.expressions.CompositeExpression.evaluateOr(CompositeExpression.java:68)
    at org.eclipse.core.internal.expressions.OrExpression.evaluate(OrExpression.java:21)
    at org.eclipse.core.internal.expressions.CompositeExpression.evaluateAnd(CompositeExpression.java:53)
    at org.eclipse.core.internal.expressions.AdaptExpression.evaluate(AdaptExpression.java:91)
    at org.eclipse.core.internal.expressions.CompositeExpression.evaluateAnd(CompositeExpression.java:53)
    at org.eclipse.core.internal.expressions.AndExpression.evaluate(AndExpression.java:29)
    at org.eclipse.ui.internal.dialogs.RegistryPageContributor.failsEnablement(RegistryPageContributor.java:311)
    at org.eclipse.ui.internal.dialogs.RegistryPageContributor.isApplicableTo(RegistryPageContributor.java:251)
    at org.eclipse.ui.internal.dialogs.PropertyPageContributorManager.getApplicableContributors(PropertyPageContributorManager.java:218)
    at org.eclipse.ui.internal.dialogs.PropertyPageContributorManager.getApplicableContributors(PropertyPageContributorManager.java:237)
    at org.eclipse.ui.dialogs.PropertyDialogAction.hasPropertyPagesFor(PropertyDialogAction.java:105)
    at org.eclipse.ui.dialogs.PropertyDialogAction.isApplicableForSelection(PropertyDialogAction.java:147)
    at org.eclipse.ui.dialogs.PropertyDialogAction.isApplicableForSelection(PropertyDialogAction.java:127)
    at org.eclipse.jdt.ui.actions.OpenViewActionGroup.fillContextMenu(OpenViewActionGroup.java:278)
    at org.eclipse.jdt.ui.actions.NavigateActionGroup.fillContextMenu(NavigateActionGroup.java:108)
    at org.eclipse.jdt.internal.ui.actions.CompositeActionGroup.fillContextMenu(CompositeActionGroup.java:75)
    at org.eclipse.jdt.internal.ui.packageview.PackageExplorerActionGroup.fillContextMenu(PackageExplorerActionGroup.java:290)
    at org.eclipse.jdt.internal.ui.packageview.PackageExplorerPart.menuAboutToShow(PackageExplorerPart.java:795)
    at org.eclipse.jface.action.MenuManager.fireAboutToShow(MenuManager.java:342)
    at org.eclipse.jface.action.MenuManager.handleAboutToShow(MenuManager.java:473)
    at org.eclipse.jface.action.MenuManager.access$1(MenuManager.java:469)
    at org.eclipse.jface.action.MenuManager$2.menuShown(MenuManager.java:495)
    at org.eclipse.swt.widgets.TypedListener.handleEvent(TypedListener.java:247)
    at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)
    at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1053)
    at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1077)
    at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1058)
    at org.eclipse.swt.widgets.Control.WM_INITMENUPOPUP(Control.java:4881)
    at org.eclipse.swt.widgets.Control.windowProc(Control.java:4557)
    at org.eclipse.swt.widgets.Canvas.windowProc(Canvas.java:341)
    at org.eclipse.swt.widgets.Decorations.windowProc(Decorations.java:1610)
    at org.eclipse.swt.widgets.Shell.windowProc(Shell.java:2061)
    at org.eclipse.swt.widgets.Display.windowProc(Display.java:4972)
    at org.eclipse.swt.internal.win32.OS.TrackPopupMenu(Native Method)
    at org.eclipse.swt.widgets.Menu._setVisible(Menu.java:256)
    at org.eclipse.swt.widgets.Display.runPopups(Display.java:4206)
    at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3748)
    at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:2701)
    at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2665)
    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)
!SUBENTRY 1 org.eclipse.core.resources 4 274 2013-01-26 22:43:47.515
!MESSAGE Resource is out of sync with the file system: '/TitleToolITdemo/AndroidManifest.xml'.

Answer 1

I restarted several times Eclipse and making several attempts to update SDK or opening any windows but nothing always the error above and others more. So, I started to carefully read some posts here to find a solution. I used this thread Eclipse Android SDK - error in building workspace and it's sugegstion to check java -version plus the other links in the thread. By the end I discovered that my Eclipse was starting a java build 1.7.2 that I don't know where it found while the highest I have in the machine is build 1.7.0_11-b21 wich mismatched with the inside project or whatsoever, I'm completely incompetent on programming, just started to learn. I edited the eclipse.ini using the help from this link http://wiki.eclipse.org/Eclipse.ini#-vm_value%3a_Windows_Example and I made my machine pointing to C:\Programmi\Java\jdk1.6.0_26\bin\javaw.exe Then saved and restarted eclipse. Anything went working again without any project lost. I wish this can be useful to someone else too. Do not forget to use also the same ADT and SDK dependency..if anything goes wrong first start using Help>Check for Updates> ADT etc one at time I discovered that the DDMS wasn't updated according to latest SDK and ADT too.