编辑1 - 主类

Question

一周前，我所拥有的每个项目都正常工作，但当我将Eclipse更新为Oxygen版本并安装JDK-9时，事情变得异常奇怪。当我尝试使用字符串时，经过一段时间（更像每次我保存项目），编译器会为我项目中的每个字符串抛出一个错误。

字符串类型被识别为不明确的类

＆＃34;类型java.lang.String是不明确的＆＃34;

所以我尝试导入java.lang.String以查看是否修复了错误：

导入后

＆＃34; java.lang包可以从多个模块访问：java.base，java.base＆＃34;

惊喜！

它没有:(
我曾尝试在Google和SO上搜索这些消息，但我一无所获...... 但是，在JDK 8中运行的代码似乎正常运行，请查看：

更改为JDK 8（1.8.0_72）

（代码在应用之前没有显示任何错误，因为我已经应用了，并再次为屏幕截图打开编译器首选项）

控制台错误：

错误：在课程me.mateusakino.ypul.yPuLTester中找不到主要方法，请将主要方法定义为：
public static void main(String[] args) 或者JavaFX应用程序类必须扩展javafx.application.Application

编辑1 - 主类

编辑5 - 编辑4 （工作空间/ .metadata / .log）

上的错误的堆栈跟踪

!SESSION 2017-10-13 13:11:39.551 -----------------------------------------------
eclipse.buildId=4.7.1.M20171009-0410
java.version=9
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

This is a continuation of log file C:\Users\Home\Desktop\Developer Folders\Java\Oxygen Workspace\.metadata\.bak_0.log
Created Time: 2017-10-13 13:43:14.245

!ENTRY org.eclipse.core.resources 4 75 2017-10-13 13:43:14.245
!MESSAGE Errors occurred during the build.
!SUBENTRY 1 org.eclipse.jdt.core 4 75 2017-10-13 13:43:14.245
!MESSAGE Errors running builder 'Java Builder' on project 'yPuL'.
!STACK 0
java.lang.NullPointerException
    at org.eclipse.jdt.internal.compiler.lookup.ModuleBinding$UnNamedModule.canAccess(ModuleBinding.java:71)
    at org.eclipse.jdt.internal.compiler.lookup.PackageBinding.getTypeOrPackage(PackageBinding.java:230)
    at org.eclipse.jdt.internal.compiler.lookup.Scope.getPackage(Scope.java:2922)
    at org.eclipse.jdt.internal.compiler.ast.QualifiedTypeReference.getTypeBinding(QualifiedTypeReference.java:108)
    at org.eclipse.jdt.internal.compiler.ast.ArrayQualifiedTypeReference.getTypeBinding(ArrayQualifiedTypeReference.java:93)
    at org.eclipse.jdt.internal.compiler.ast.TypeReference.internalResolveType(TypeReference.java:495)
    at org.eclipse.jdt.internal.compiler.ast.ArrayQualifiedTypeReference.internalResolveType(ArrayQualifiedTypeReference.java:107)
    at org.eclipse.jdt.internal.compiler.ast.TypeReference.resolveType(TypeReference.java:586)
    at org.eclipse.jdt.internal.compiler.ast.TypeReference.resolveType(TypeReference.java:582)
    at org.eclipse.jdt.internal.compiler.lookup.SourceTypeBinding.resolveTypesWithSuspendedTempErrorHandlingPolicy(SourceTypeBinding.java:1932)
    at org.eclipse.jdt.internal.compiler.lookup.SourceTypeBinding.resolveTypesFor(SourceTypeBinding.java:1835)
    at org.eclipse.jdt.internal.compiler.lookup.SourceTypeBinding.methods(SourceTypeBinding.java:1525)
    at org.eclipse.jdt.internal.compiler.lookup.SourceTypeBinding.internalFaultInTypeForFieldsAndMethods(SourceTypeBinding.java:907)
    at org.eclipse.jdt.internal.compiler.lookup.SourceTypeBinding.faultInTypesForFieldsAndMethods(SourceTypeBinding.java:902)
    at org.eclipse.jdt.internal.compiler.lookup.CompilationUnitScope.faultInTypes(CompilationUnitScope.java:514)
    at org.eclipse.jdt.internal.compiler.Compiler.process(Compiler.java:882)
    at org.eclipse.jdt.internal.compiler.ProcessTaskManager.run(ProcessTaskManager.java:141)
    at java.base/java.lang.Thread.run(Thread.java:844)

!ENTRY org.eclipse.core.resources 4 2 2017-10-13 13:43:24.691
!MESSAGE Problems occurred when invoking code from plug-in: "org.eclipse.core.resources".
!STACK 0
java.lang.NullPointerException

!ENTRY org.eclipse.core.resources 4 75 2017-10-13 13:43:24.695
!MESSAGE Errors occurred during the build.
!SUBENTRY 1 org.eclipse.jdt.core 4 75 2017-10-13 13:43:24.695
!MESSAGE Errors running builder 'Java Builder' on project 'yPuL'.
!STACK 0
java.lang.NullPointerException

!ENTRY org.eclipse.core.resources 4 2 2017-10-13 13:43:39.104
!MESSAGE Problems occurred when invoking code from plug-in: "org.eclipse.core.resources".
!STACK 0
java.lang.NullPointerException

!ENTRY org.eclipse.core.resources 4 75 2017-10-13 13:43:39.110
!MESSAGE Errors occurred during the build.
!SUBENTRY 1 org.eclipse.jdt.core 4 75 2017-10-13 13:43:39.110
!MESSAGE Errors running builder 'Java Builder' on project 'yPuL'.
!STACK 0
java.lang.NullPointerException

!ENTRY org.eclipse.core.resources 4 2 2017-10-13 13:44:37.810
!MESSAGE Problems occurred when invoking code from plug-in: "org.eclipse.core.resources".
!STACK 0
java.lang.NullPointerException
    at org.eclipse.jdt.internal.compiler.lookup.ModuleBinding$UnNamedModule.canAccess(ModuleBinding.java:71)
    at org.eclipse.jdt.internal.compiler.lookup.PackageBinding.getTypeOrPackage(PackageBinding.java:230)
    at org.eclipse.jdt.internal.compiler.lookup.Scope.getPackage(Scope.java:2922)
    at org.eclipse.jdt.internal.compiler.ast.QualifiedTypeReference.getTypeBinding(QualifiedTypeReference.java:108)
    at org.eclipse.jdt.internal.compiler.ast.ArrayQualifiedTypeReference.getTypeBinding(ArrayQualifiedTypeReference.java:93)
    at org.eclipse.jdt.internal.compiler.ast.TypeReference.internalResolveType(TypeReference.java:495)
    at org.eclipse.jdt.internal.compiler.ast.ArrayQualifiedTypeReference.internalResolveType(ArrayQualifiedTypeReference.java:107)
    at org.eclipse.jdt.internal.compiler.ast.TypeReference.resolveType(TypeReference.java:586)
    at org.eclipse.jdt.internal.compiler.ast.TypeReference.resolveType(TypeReference.java:582)
    at org.eclipse.jdt.internal.compiler.lookup.SourceTypeBinding.resolveTypesWithSuspendedTempErrorHandlingPolicy(SourceTypeBinding.java:1932)
    at org.eclipse.jdt.internal.compiler.lookup.SourceTypeBinding.resolveTypesFor(SourceTypeBinding.java:1835)
    at org.eclipse.jdt.internal.compiler.lookup.SourceTypeBinding.methods(SourceTypeBinding.java:1525)
    at org.eclipse.jdt.internal.compiler.lookup.SourceTypeBinding.internalFaultInTypeForFieldsAndMethods(SourceTypeBinding.java:907)
    at org.eclipse.jdt.internal.compiler.lookup.SourceTypeBinding.faultInTypesForFieldsAndMethods(SourceTypeBinding.java:902)
    at org.eclipse.jdt.internal.compiler.lookup.CompilationUnitScope.faultInTypes(CompilationUnitScope.java:514)
    at org.eclipse.jdt.internal.compiler.Compiler.process(Compiler.java:882)
    at org.eclipse.jdt.internal.compiler.ProcessTaskManager.run(ProcessTaskManager.java:141)
    at java.base/java.lang.Thread.run(Thread.java:844)

!ENTRY org.eclipse.core.resources 4 75 2017-10-13 13:44:37.814
!MESSAGE Errors occurred during the build.
!SUBENTRY 1 org.eclipse.jdt.core 4 75 2017-10-13 13:44:37.814
!MESSAGE Errors running builder 'Java Builder' on project 'yPuL'.
!STACK 0
java.lang.NullPointerException
    at org.eclipse.jdt.internal.compiler.lookup.ModuleBinding$UnNamedModule.canAccess(ModuleBinding.java:71)
    at org.eclipse.jdt.internal.compiler.lookup.PackageBinding.getTypeOrPackage(PackageBinding.java:230)
    at org.eclipse.jdt.internal.compiler.lookup.Scope.getPackage(Scope.java:2922)
    at org.eclipse.jdt.internal.compiler.ast.QualifiedTypeReference.getTypeBinding(QualifiedTypeReference.java:108)
    at org.eclipse.jdt.internal.compiler.ast.ArrayQualifiedTypeReference.getTypeBinding(ArrayQualifiedTypeReference.java:93)
    at org.eclipse.jdt.internal.compiler.ast.TypeReference.internalResolveType(TypeReference.java:495)
    at org.eclipse.jdt.internal.compiler.ast.ArrayQualifiedTypeReference.internalResolveType(ArrayQualifiedTypeReference.java:107)
    at org.eclipse.jdt.internal.compiler.ast.TypeReference.resolveType(TypeReference.java:586)
    at org.eclipse.jdt.internal.compiler.ast.TypeReference.resolveType(TypeReference.java:582)
    at org.eclipse.jdt.internal.compiler.lookup.SourceTypeBinding.resolveTypesWithSuspendedTempErrorHandlingPolicy(SourceTypeBinding.java:1932)
    at org.eclipse.jdt.internal.compiler.lookup.SourceTypeBinding.resolveTypesFor(SourceTypeBinding.java:1835)
    at org.eclipse.jdt.internal.compiler.lookup.SourceTypeBinding.methods(SourceTypeBinding.java:1525)
    at org.eclipse.jdt.internal.compiler.lookup.SourceTypeBinding.internalFaultInTypeForFieldsAndMethods(SourceTypeBinding.java:907)
    at org.eclipse.jdt.internal.compiler.lookup.SourceTypeBinding.faultInTypesForFieldsAndMethods(SourceTypeBinding.java:902)
    at org.eclipse.jdt.internal.compiler.lookup.CompilationUnitScope.faultInTypes(CompilationUnitScope.java:514)
    at org.eclipse.jdt.internal.compiler.Compiler.process(Compiler.java:882)
    at org.eclipse.jdt.internal.compiler.ProcessTaskManager.run(ProcessTaskManager.java:141)
    at java.base/java.lang.Thread.run(Thread.java:844)

!ENTRY org.eclipse.core.resources 4 2 2017-10-13 13:44:53.701
!MESSAGE Problems occurred when invoking code from plug-in: "org.eclipse.core.resources".
!STACK 0
java.lang.NullPointerException
    at org.eclipse.jdt.internal.compiler.lookup.ModuleBinding$UnNamedModule.canAccess(ModuleBinding.java:71)
    at org.eclipse.jdt.internal.compiler.lookup.PackageBinding.getTypeOrPackage(PackageBinding.java:230)
    at org.eclipse.jdt.internal.compiler.lookup.Scope.getPackage(Scope.java:2922)
    at org.eclipse.jdt.internal.compiler.ast.QualifiedTypeReference.getTypeBinding(QualifiedTypeReference.java:108)
    at org.eclipse.jdt.internal.compiler.ast.ArrayQualifiedTypeReference.getTypeBinding(ArrayQualifiedTypeReference.java:93)
    at org.eclipse.jdt.internal.compiler.ast.TypeReference.internalResolveType(TypeReference.java:495)
    at org.eclipse.jdt.internal.compiler.ast.ArrayQualifiedTypeReference.internalResolveType(ArrayQualifiedTypeReference.java:107)
    at org.eclipse.jdt.internal.compiler.ast.TypeReference.resolveType(TypeReference.java:586)
    at org.eclipse.jdt.internal.compiler.ast.TypeReference.resolveType(TypeReference.java:582)
    at org.eclipse.jdt.internal.compiler.lookup.SourceTypeBinding.resolveTypesWithSuspendedTempErrorHandlingPolicy(SourceTypeBinding.java:1932)
    at org.eclipse.jdt.internal.compiler.lookup.SourceTypeBinding.resolveTypesFor(SourceTypeBinding.java:1835)
    at org.eclipse.jdt.internal.compiler.lookup.SourceTypeBinding.methods(SourceTypeBinding.java:1525)
    at org.eclipse.jdt.internal.compiler.lookup.SourceTypeBinding.internalFaultInTypeForFieldsAndMethods(SourceTypeBinding.java:907)
    at org.eclipse.jdt.internal.compiler.lookup.SourceTypeBinding.faultInTypesForFieldsAndMethods(SourceTypeBinding.java:902)
    at org.eclipse.jdt.internal.compiler.lookup.CompilationUnitScope.faultInTypes(CompilationUnitScope.java:514)
    at org.eclipse.jdt.internal.compiler.Compiler.process(Compiler.java:882)
    at org.eclipse.jdt.internal.compiler.ProcessTaskManager.run(ProcessTaskManager.java:141)
    at java.base/java.lang.Thread.run(Thread.java:844)

!ENTRY org.eclipse.core.resources 4 75 2017-10-13 13:44:53.706
!MESSAGE Errors occurred during the build.
!SUBENTRY 1 org.eclipse.jdt.core 4 75 2017-10-13 13:44:53.706
!MESSAGE Errors running builder 'Java Builder' on project 'yPuL'.
!STACK 0
java.lang.NullPointerException
    at org.eclipse.jdt.internal.compiler.lookup.ModuleBinding$UnNamedModule.canAccess(ModuleBinding.java:71)
    at org.eclipse.jdt.internal.compiler.lookup.PackageBinding.getTypeOrPackage(PackageBinding.java:230)
    at org.eclipse.jdt.internal.compiler.lookup.Scope.getPackage(Scope.java:2922)
    at org.eclipse.jdt.internal.compiler.ast.QualifiedTypeReference.getTypeBinding(QualifiedTypeReference.java:108)
    at org.eclipse.jdt.internal.compiler.ast.ArrayQualifiedTypeReference.getTypeBinding(ArrayQualifiedTypeReference.java:93)
    at org.eclipse.jdt.internal.compiler.ast.TypeReference.internalResolveType(TypeReference.java:495)
    at org.eclipse.jdt.internal.compiler.ast.ArrayQualifiedTypeReference.internalResolveType(ArrayQualifiedTypeReference.java:107)
    at org.eclipse.jdt.internal.compiler.ast.TypeReference.resolveType(TypeReference.java:586)
    at org.eclipse.jdt.internal.compiler.ast.TypeReference.resolveType(TypeReference.java:582)
    at org.eclipse.jdt.internal.compiler.lookup.SourceTypeBinding.resolveTypesWithSuspendedTempErrorHandlingPolicy(SourceTypeBinding.java:1932)
    at org.eclipse.jdt.internal.compiler.lookup.SourceTypeBinding.resolveTypesFor(SourceTypeBinding.java:1835)
    at org.eclipse.jdt.internal.compiler.lookup.SourceTypeBinding.methods(SourceTypeBinding.java:1525)
    at org.eclipse.jdt.internal.compiler.lookup.SourceTypeBinding.internalFaultInTypeForFieldsAndMethods(SourceTypeBinding.java:907)
    at org.eclipse.jdt.internal.compiler.lookup.SourceTypeBinding.faultInTypesForFieldsAndMethods(SourceTypeBinding.java:902)
    at org.eclipse.jdt.internal.compiler.lookup.CompilationUnitScope.faultInTypes(CompilationUnitScope.java:514)
    at org.eclipse.jdt.internal.compiler.Compiler.process(Compiler.java:882)
    at org.eclipse.jdt.internal.compiler.ProcessTaskManager.run(ProcessTaskManager.java:141)
    at java.base/java.lang.Thread.run(Thread.java:844)
!SESSION 2017-10-13 13:46:42.392 -----------------------------------------------
eclipse.buildId=4.7.1.M20171009-0410
java.version=9
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.jface 2 0 2017-10-13 13:46:49.852
!MESSAGE Keybinding conflicts occurred.  They may interfere with normal accelerator operation.
!SUBENTRY 1 org.eclipse.jface 2 0 2017-10-13 13:46:49.852
!MESSAGE A conflict occurred for CTRL+TAB:
Binding(CTRL+TAB,
    ParameterizedCommand(Command(org.eclipse.ui.window.nextEditor,Next Editor,
        Switch to the next editor,
        Category(org.eclipse.ui.category.window,Window,null,true),
        org.eclipse.ui.internal.WorkbenchHandlerServiceHandler@5e8359da,
        ,,true),null),
    org.eclipse.ui.defaultAcceleratorConfiguration,
    org.eclipse.ui.contexts.window,,,system)
Binding(CTRL+TAB,
    ParameterizedCommand(Command(org.eclipse.ui.window.nextEditor,Next Editor,
        Switch to the next editor,
        Category(org.eclipse.ui.category.window,Window,null,true),
        org.eclipse.ui.internal.WorkbenchHandlerServiceHandler@5e8359da,
        ,,true),null),
    org.eclipse.ui.defaultAcceleratorConfiguration,
    org.eclipse.ui.contexts.window,,,system)
!SUBENTRY 1 org.eclipse.jface 2 0 2017-10-13 13:46:49.852
!MESSAGE A conflict occurred for CTRL+SHIFT+TAB:
Binding(CTRL+SHIFT+TAB,
    ParameterizedCommand(Command(org.eclipse.ui.window.previousEditor,Previous Editor,
        Switch to the previous editor,
        Category(org.eclipse.ui.category.window,Window,null,true),
        org.eclipse.ui.internal.WorkbenchHandlerServiceHandler@36b6802f,
        ,,true),null),
    org.eclipse.ui.defaultAcceleratorConfiguration,
    org.eclipse.ui.contexts.window,,,system)
Binding(CTRL+SHIFT+TAB,
    ParameterizedCommand(Command(org.eclipse.ui.window.previousEditor,Previous Editor,
        Switch to the previous editor,
        Category(org.eclipse.ui.category.window,Window,null,true),
        org.eclipse.ui.internal.WorkbenchHandlerServiceHandler@36b6802f,
        ,,true),null),
    org.eclipse.ui.defaultAcceleratorConfiguration,
    org.eclipse.ui.contexts.window,,,system)

!ENTRY com.vaadin.designer2 1 0 2017-10-13 13:47:00.882
!MESSAGE Schedule fetching all notifications

!ENTRY com.vaadin.designer2 1 0 2017-10-13 13:47:02.845
!MESSAGE Parse notifications

!ENTRY com.vaadin.designer2 1 0 2017-10-13 13:47:03.278
!MESSAGE Requesting user info (notification settings URL)

!ENTRY com.vaadin.designer2 1 0 2017-10-13 13:47:04.704
!MESSAGE HTTP Response code :200

!ENTRY org.eclipse.egit.ui 2 0 2017-10-13 13:47:06.014
!MESSAGE Warning: The environment variable HOME is not set. The following directory will be used to store the Git
user global configuration and to define the default location to store repositories: 'C:\Users\Home'. If this is
not correct please set the HOME environment variable and restart Eclipse. Otherwise Git for Windows and
EGit might behave differently since they see different configuration options.
This warning can be switched off on the Team > Git > Confirmations and Warnings preference page.

!ENTRY org.eclipse.dltk.core 4 0 2017-10-13 13:47:07.129
!MESSAGE Unable to find any indexer

!ENTRY org.apache.ivyde.eclipse 1 0 2017-10-13 13:48:10.554
!MESSAGE starting IvyDE plugin

!ENTRY org.apache.ivyde.eclipse 1 0 2017-10-13 13:48:10.571
!MESSAGE IvyDE plugin started

!ENTRY org.eclipse.ui 2 2 2017-10-13 13:48:12.395
!MESSAGE Invalid property category path: org.eclipse.cdt.managedbuilder.ui.properties.Page_head_build (bundle: org.eclipse.cdt.ui, propertyPage: org.eclipse.cdt.managedbuilder.ui.properties.BuildLogPreferencePage)

!ENTRY org.eclipse.jface 4 2 2017-10-13 13:48:45.611
!MESSAGE Problems occurred when invoking code from plug-in: "org.eclipse.jface".
!STACK 0
java.lang.IllegalArgumentException
    at org.eclipse.core.resources.ProjectScope.<init>(ProjectScope.java:58)
    at com.vaadin.designer2.eclipse.preferences.VisualDesignerPreferences.getProjectPreferences(VisualDesignerPreferences.java:680)
    at com.vaadin.designer2.eclipse.preferences.VisualDesignerPreferences.getDefaultDesigner(VisualDesignerPreferences.java:245)
    at com.vaadin.designer2.eclipse.preferences.DesignerProjectPreferencePage.createDesignerSelection(DesignerProjectPreferencePage.java:179)
    at com.vaadin.designer2.eclipse.preferences.DesignerProjectPreferencePage.createContents(DesignerProjectPreferencePage.java:109)
    at org.eclipse.jface.preference.PreferencePage.createControl(PreferencePage.java:241)
    at org.eclipse.jface.preference.PreferenceDialog.createPageControl(PreferenceDialog.java:1426)
    at org.eclipse.jface.preference.PreferenceDialog$8.run(PreferenceDialog.java:1193)
    at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
    at org.eclipse.ui.internal.JFaceUtil.lambda$0(JFaceUtil.java:44)
    at org.eclipse.jface.util.SafeRunnable.run(SafeRunnable.java:173)
    at org.eclipse.jface.preference.PreferenceDialog.showPage(PreferenceDialog.java:1185)
    at org.eclipse.ui.internal.dialogs.FilteredPreferenceDialog.showPage(FilteredPreferenceDialog.java:591)
    at org.eclipse.jface.preference.PreferenceDialog$5.lambda$0(PreferenceDialog.java:657)
    at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:70)
    at org.eclipse.jface.preference.PreferenceDialog$5.selectionChanged(PreferenceDialog.java:654)
    at org.eclipse.jface.viewers.StructuredViewer$3.run(StructuredViewer.java:872)
    at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
    at org.eclipse.ui.internal.JFaceUtil.lambda$0(JFaceUtil.java:44)
    at org.eclipse.jface.util.SafeRunnable.run(SafeRunnable.java:173)
    at org.eclipse.jface.viewers.StructuredViewer.firePostSelectionChanged(StructuredViewer.java:869)
    at org.eclipse.jface.viewers.StructuredViewer.handlePostSelect(StructuredViewer.java:1238)
    at org.eclipse.jface.viewers.StructuredViewer.lambda$0(StructuredViewer.java:1261)
    at org.eclipse.swt.events.SelectionListener$1.widgetSelected(SelectionListener.java:81)
    at org.eclipse.jface.util.OpenStrategy.firePostSelectionEvent(OpenStrategy.java:261)
    at org.eclipse.jface.util.OpenStrategy.access$5(OpenStrategy.java:256)
    at org.eclipse.jface.util.OpenStrategy$1.lambda$1(OpenStrategy.java:426)
    at org.eclipse.swt.widgets.RunnableLock.run(RunnableLock.java:37)
    at org.eclipse.swt.widgets.Synchronizer.runAsyncMessages(Synchronizer.java:182)
    at org.eclipse.swt.widgets.Display.runAsyncMessages(Display.java:4213)
    at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3820)
    at org.eclipse.jface.window.Window.runEventLoop(Window.java:818)
    at org.eclipse.jface.window.Window.open(Window.java:794)
    at org.eclipse.ui.dialogs.PropertyDialogAction.run(PropertyDialogAction.java:157)
    at org.eclipse.jface.action.Action.runWithEvent(Action.java:473)
    at org.eclipse.jface.action.ActionContributionItem.handleWidgetSelection(ActionContributionItem.java:565)
    at org.eclipse.jface.action.ActionContributionItem.lambda$4(ActionContributionItem.java:397)
    at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:86)
    at org.eclipse.swt.widgets.Display.sendEvent(Display.java:4428)
    at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1079)
    at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:4238)
    at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3817)
    at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$5.run(PartRenderingEngine.java:1150)
    at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:336)
    at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.run(PartRenderingEngine.java:1039)
    at org.eclipse.e4.ui.internal.workbench.E4Workbench.createAndRunUI(E4Workbench.java:153)
    at org.eclipse.ui.internal.Workbench.lambda$3(Workbench.java:680)
    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(NativeMethodAccessorImpl.java:62)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.base/java.lang.reflect.Method.invoke(Method.java:564)
    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)

编辑7：

我可以reproduce在另一个工作区（Temp Workspace）中，这里是来自@howlger的.classpath文件：

<?xml version="1.0" encoding="UTF-8"?>
<classpath>
    <classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER"/>
    <classpathentry kind="src" path="src"/>
    <classpathentry kind="output" path="bin"/>
</classpath>

编辑8 - Eclipse报告（由Howlger提问）：

https://bugs.eclipse.org/bugs/show_bug.cgi?id=526020

详细说明：

操作系统：Windows 10 Home（64位）
JDK 9.0
初始Eclipse：氧气释放（4.7.0）构建ID：20170620-1800
Current Eclipse：Oxygen.1a Release（4.7.1a）Build id：20171005-1200
编辑4：项目设置：
- 参考图书馆：jRegex
- 编码：UTF-8
- Compiler Settings
- Execution Envieroments
编辑4： Java 9版本：build 9 + 181
编辑4 ：Java HotSpot（TM）64位服务器VM（版本9 + 181，混合模式）
编辑6： All Eclipse's Plugins
如果需要任何其他信息，请在评论部分询问......

我尝试了什么：

重新启动IDE
搜索Java Proposals / Completion中是否有多个字符串（只有一个，java.lang＆＃39; s）。
检查JRE系统库是否有多个java.base包（只有一个，来自jrt-fs.jar）。
编辑2 ：通过eclipse.ini
编辑2 ：将eclipse更新为版本：4.7.1a（Too many images in this post already）
编辑3 ：检查项目和/或Eclipse偏好设置中的双重JDK（Image link）
编辑4 ：重建java索引（没有工作），启用New Java index并重新重建：工作了大约3分钟，但随后出现了这个错误并且出现了故障再次回来：java.lang.ClassCastException建设时
编辑4 ：从默认库中删除JDK 9并将其重新添加回来，与上面相同，但这次它将错误：java.lang.NullPointerException抛出到工作区，并且即使在重新启动IDE之后，仍然会发生String错误...（BTW，this warning出现在package关键字中，不确定它是否已经在此之前...）

Answer 1

在screenshot showing all installed Eclipse plug-ins中，我看到一些非常可疑的内容：您安装了两个相互矛盾的功能：

Eclipse Java开发工具 - 3.13.1.v20171009-0 ... - 好
Eclipse JDT（Java开发工具）针对Oxygen开发流的Java 9支持（BETA）补丁 - 1.1.1.v20170826-05 ... - 不好

根据我对Eclipse中Patch功能的理解，第二个（较旧的）功能可能会覆盖前一个（较新的）功能的插件。这仍然意味着在更新到Oxygen.1a（支持Java 9的正式版本）之后，您有效地运行了几个星期的测试版。

要仔细检查，您可以切换到 Eclipse安装详细信息对话框的插件标签，然后搜索＆＃34; jdt＆＃34;。< / p>

这个观察结果可以很容易地解释为什么你仍然受到在发布之前已经修复的错误的影响。

解决方案：请尝试卸载修补程序功能（并查看配置

编辑：可以在compiler settings，合规性＆＃34; 9（BETA）＆＃34;清楚地表明您没有运行JDT的发行版本。

Answer 2

对于Java 9支持，您需要：

Eclipse Oxygen.1a，可从https://www.eclipse.org/downloads/eclipse-packages/
获取
或
根据https://wiki.eclipse.org/Configure_Eclipse_for_Java_9

选项1显然更简单，只要您可以控制安装和使用的Eclipse版本。

Answer 3

对我来说，通过从Eclipse中删除项目（以及从磁盘中删除）来解决问题。然后git-clone并创建项目，问题就解决了。

Answer 4

我在Eclipse Oxygen中遇到同样的问题，明确导入String包。更新eclipse并删除项目中使用的用户库后问题得到解决。

Answer 5

Idk如果这有帮助，但我遇到了类似的问题：基本类无法识别。

我的混淆源于将rt.jar（和其他）捆绑成无扩展“模块”文件的新Java惯例---改变了一个十年前的类参考策略。

使用JDK-10（或JDK-9）编译Eclipse需要做一些事情：

Window-＆gt; Preferences-＆gt; Java-＆gt; Installed JREs-＆gt; Add ...-＆gt; Standard VM - ＆gt;（导航到JDK-10）
Window-＆gt; Preferences-＆gt; Java-＆gt; Compiler-＆gt; JDK合规性：编译器合规级别：10
右键单击Project-＆gt; Build Path-＆gt; Configure Build Path-＆gt; Java Build Path-＆gt; Libraries-＆gt; Highlight Modulepath-＆gt; Add Library-＆gt; JRE System Library-＆gt; Next-＆gt ;选择JRE 9/10 Per config-＆gt; Finish

注意：除非您执行了＃2，否则上述＃3是不可能的，因为在您提高编译器合规性级别（在＃2中）之前，Eclipse不会引入“Modulepath”选项（在＃3中）。

不可否认，这对大多数人来说可能是显而易见的......唉，我并不是最重要的。

JDK-9不允许我使用字符串：＆＃34; java.lang.String含糊不清＆＃34;？

字符串类型被识别为不明确的类

导入后

惊喜！

更改为JDK 8（1.8.0_72）

控制台错误：

编辑1 - 主类

编辑5 - 编辑4 （工作空间/ .metadata / .log）

编辑7：

编辑8 - Eclipse报告（由Howlger提问）：

详细说明：

我尝试了什么：

5 个答案: