Eclipse workspace wont start - eclipse

Question

Well, my eclipse workspace wont start anymore, I stopped programming for a while, and then now I wanted to come back and I cant open my eclipse workspace, here is the log file: https://pastebin.com/ruyDTGCD
Ive tried removing workspace.iwo or whatever it was called but that didn't work, and I put it back again, and another one ive tried is putting javaw inside of the eclipse folder.
!SESSION 2019-07-08 09:25:37.875 -----------------------------------------------
eclipse.buildId=4.7.0.I20170612-0950
java.version=9.0.4
java.vendor=Oracle Corporation
BootLoader constants: OS=win32, ARCH=x86_64, WS=win32, NL=en_US
Framework arguments: -product org.eclipse.epp.package.java.product
Command-line arguments: -os win32 -ws win32 -arch x86_64 -product org.eclipse.epp.package.java.product
!ENTRY org.eclipse.osgi 4 0 2019-07-08 09:25:58.212
!MESSAGE Application error
!STACK 1
org.eclipse.e4.core.di.InjectionException: java.lang.NoClassDefFoundError: javax/annotation/PostConstruct
at org.eclipse.e4.core.internal.di.InjectorImpl.internalMake(InjectorImpl.java:410)
at org.eclipse.e4.core.internal.di.InjectorImpl.make(InjectorImpl.java:318)
at org.eclipse.e4.core.contexts.ContextInjectionFactory.make(ContextInjectionFactory.java:162)
at org.eclipse.e4.ui.internal.workbench.swt.E4Application.createDefaultHeadlessContext(E4Application.java:491)
at org.eclipse.e4.ui.internal.workbench.swt.E4Application.createDefaultContext(E4Application.java:505)
at org.eclipse.e4.ui.internal.workbench.swt.E4Application.createE4Workbench(E4Application.java:204)
at org.eclipse.ui.internal.Workbench.lambda$3(Workbench.java:614)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:336)
at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:594)
at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:148)
at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:151)
at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:196)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:134)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:104)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:388)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:243)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.base/java.lang.reflect.Method.invoke(Unknown Source)
at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:653)
at org.eclipse.equinox.launcher.Main.basicRun(Main.java:590)
at org.eclipse.equinox.launcher.Main.run(Main.java:1499)
at org.eclipse.equinox.launcher.Main.main(Main.java:1472)
Caused by: java.lang.NoClassDefFoundError: javax/annotation/PostConstruct
at org.eclipse.e4.core.internal.di.InjectorImpl.inject(InjectorImpl.java:124)
at org.eclipse.e4.core.internal.di.InjectorImpl.internalMake(InjectorImpl.java:399)
... 23 more
Caused by: java.lang.ClassNotFoundException: javax.annotation.PostConstruct cannot be found by org.eclipse.e4.core.di_1.6.100.v20170421-1418
at org.eclipse.osgi.internal.loader.BundleLoader.findClassInternal(BundleLoader.java:433)
at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:395)
at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:387)
at org.eclipse.osgi.internal.loader.ModuleClassLoader.loadClass(ModuleClassLoader.java:150)
at java.base/java.lang.ClassLoader.loadClass(Unknown Source)
... 25 more
basically you see the log file.
I just updated the log file now by renaming the old one, so I get a new one. This is everything in the log file.

Answer 1

The Eclipse .metadata folder contains a lot of information on how Eclipse is used and configured. This could possibly get corrupted somehow causing Eclipse not to start anymore.
To check whether this is the case just open up Eclipse on a complete fresh workspace. Eclipse should then generate a fresh .metadata folder and should at least start up again.
If the startup is successful one can think about importing the projects from the old workspace again and continue from there. Eclipse has to be reconfigured then.