Eclipse Juno内容辅助错误

Question

我已经安装了Eclipse Juno Build id：20120614-1722。 java jdk版本是：

$ java -version

java version "1.7.0_07"
Java(TM) SE Runtime Environment (build 1.7.0_07-b10)
Java HotSpot(TM) Server VM (build 23.3-b01, mixed mode)

Jre版本是：

$ javac -version

javac 1.7.0_07

问题是，每当我想调用一个方法，例如是System.out.print（）;我得到以下错误和跟踪日志。

错误

以下是tracelog的开头。

Exception in thread "AutoAssist Delay" org.eclipse.swt.SWTException: 
Failed to execute runnable (java.lang.LinkageError: 
loader constraint violation: when resolving method                                                                   "org.eclipse.recommenders.utils.rcp.JdtUtils.
createUnresolvedType(Lorg/eclipse/jdt/internal/compiler/lookup/TypeBinding;)
Lcom/google/common/base Optional;" 

the class loader (instance of org/eclipse/osgi/internal/baseadaptor/DefaultClassLoader) 
of the current class,
org/eclipse/recommenders/internal/completion/rcp/BaseRecommendersCompletionContext, 
and the class loader (instance of org/eclipse/osgi/internal/baseadaptor/DefaultClassLoader)
for resolved class,org/eclipse/recommenders/utils/rcp/JdtUtils
have different Class objects for the type 
pse.recommenders.utils.rcp.JdtUtils.
createUnresolvedType(Lorg/eclipse/jdt/internal/compiler
/lookup/TypeBinding;)Lcom/google/common/base/Optional; used in the signature)
        at org.eclipse.swt.SWT.error(SWT.java:4361)
        at org.eclipse.swt.SWT.error(SWT.java:4276)
        at org.eclipse.swt.widgets.Synchronizer.syncExec(Synchronizer.java:196)
        at org.eclipse.ui.internal.UISynchronizer.syncExec(UISynchronizer.java:150)
        at org.eclipse.swt.widgets.Display.syncExec(Display.java:4291)