我有一个日食问题。在我的布局中，当我尝试放置一个PlusOneButton eclipse时说：
无法实例化以下类： com.google.android.gms.plus.PlusOneButton（Open Class，Show Error Log） 有关详细信息，请参阅错误日志（窗口＆gt;显示视图）。
java.lang.NullPointerException
at com.google.android.gms.plus.PlusOneDummyView$b.isValid(Unknown Source)
at com.google.android.gms.plus.PlusOneDummyView.eN(Unknown Source)
at com.google.android.gms.plus.PlusOneDummyView.<init>(Unknown Source)
at com.google.android.gms.internal.ht.a(Unknown Source)
at com.google.android.gms.plus.PlusOneButton.p(Unknown Source)
at com.google.android.gms.plus.PlusOneButton.<init>(Unknown Source)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at com.android.ide.eclipse.adt.internal.editors.layout.ProjectCallback.instantiateClass(ProjectCallback.java:422)
at com.android.ide.eclipse.adt.internal.editors.layout.ProjectCallback.loadView(ProjectCallback.java:179)
at android.view.BridgeInflater.loadCustomView(BridgeInflater.java:207)
at android.view.BridgeInflater.createViewFromTag(BridgeInflater.java:135)
at android.view.LayoutInflater.rInflate_Original(LayoutInflater.java:755)
at android.view.LayoutInflater_Delegate.rInflate(LayoutInflater_Delegate.java:64)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:727)
at android.view.LayoutInflater.rInflate_Original(LayoutInflater.java:758)
at android.view.LayoutInflater_Delegate.rInflate(LayoutInflater_Delegate.java:64)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:727)
at android.view.LayoutInflater.inflate(LayoutInflater.java:492)
at android.view.LayoutInflater.inflate(LayoutInflater.java:373)
at com.android.layoutlib.bridge.impl.RenderSessionImpl.inflate(RenderSessionImpl.java:399)
at com.android.layoutlib.bridge.Bridge.createSession(Bridge.java:336)
at com.android.ide.common.rendering.LayoutLibrary.createSession(LayoutLibrary.java:334)
at com.android.ide.eclipse.adt.internal.editors.layout.gle2.RenderService.createRenderSession(RenderService.java:451)
at com.android.ide.eclipse.adt.internal.editors.layout.gle2.GraphicalEditorPart.renderWithBridge(GraphicalEditorPart.java:1545)
at com.android.ide.eclipse.adt.internal.editors.layout.gle2.GraphicalEditorPart.recomputeLayout(GraphicalEditorPart.java:1302)
at com.android.ide.eclipse.adt.internal.editors.layout.gle2.GraphicalEditorPart.changed(GraphicalEditorPart.java:718)
at com.android.ide.eclipse.adt.internal.editors.layout.gle2.GraphicalEditorPart.onTargetChange(GraphicalEditorPart.java:1189)
at com.android.ide.eclipse.adt.internal.editors.layout.LayoutEditorDelegate.onDescriptorsChanged(LayoutEditorDelegate.java:916)
at com.android.ide.eclipse.adt.internal.editors.layout.LayoutEditorDelegate.delegateInitUiRootNode(LayoutEditorDelegate.java:835)
at com.android.ide.eclipse.adt.internal.editors.layout.gle2.GraphicalEditorPart$TargetListener.updateEditor(GraphicalEditorPart.java:946)
at com.android.ide.eclipse.adt.internal.editors.layout.gle2.GraphicalEditorPart$TargetListener.onTargetLoaded(GraphicalEditorPart.java:910)
at com.android.ide.eclipse.adt.AdtPlugin$11.run(AdtPlugin.java:1759)
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:4144)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3761)
at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$9.run(PartRenderingEngine.java:1053)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.run(PartRenderingEngine.java:942)
at org.eclipse.e4.ui.internal.workbench.E4Workbench.createAndRunUI(E4Workbench.java:86)
at org.eclipse.ui.internal.Workbench$5.run(Workbench.java:588)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:543)
at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)
at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:124)
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:353)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:180)
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:629)
at org.eclipse.equinox.launcher.Main.basicRun(Main.java:584)
at org.eclipse.equinox.launcher.Main.run(Main.java:1438)
at org.eclipse.equinox.launcher.Main.main(Main.java:1414)
日志消息是：
com.google.android.gms.plus.PlusOneButton无法实例化。
奇怪的是，例如SignIn不会给我任何问题，只有+1按钮，并且在我的设备中运行应用程序，一切都显示完美。任何想法为什么eclipse错了？