在一个项目中创建新的XML文件，使问题出现，错误日志如下：

 显示java.lang.NullPointerException
    异常详细信息记录在窗口＆GT;显示视图＆gt;错误日志
    以下类不能被实例化：
     -  android.support.v7.internal.app.WindowDecorActionBar（公开课，显示错误日志）
     -  android.support.v7.internal.widget.ActionBarContextView（公开课，显示错误日志）
     -  android.support.v7.widget.Toolbar（公开课，显示错误日志）

...............

显示java.lang.NullPointerException
    在android.support.v7.internal.widget.ActionBarOverlayLayout.getDecorToolbar(ActionBarOverlayLayout.java:594)
    在android.support.v7.internal.widget.ActionBarOverlayLayout.pullChildren(ActionBarOverlayLayout.java:583)
    在android.support.v7.internal.widget.ActionBarOverlayLayout.onMeasure（ActionBarOverlayLayout.java:368）
    在android.view.View.measure（View.java:17547）
    在android.view.ViewGroup.measureChildWithMargins（ViewGroup.java:5535）
    在android.widget.LinearLayout.measureChildBeforeLayout（LinearLayout.java:1436）
    在android.widget.LinearLayout.measureVertical（LinearLayout.java:722）
    在android.widget.LinearLayout.onMeasure（LinearLayout.java:613）
    在android.view.View.measure（View.java:17547）
    在android.widget.LinearLayout.measureVertical（LinearLayout.java:875）
    在android.widget.LinearLayout.onMeasure（LinearLayout.java:613）
    在android.view.View.measure（View.java:17547）
    在com.android.layoutlib.bridge.impl.RenderSessionImpl.measureView（RenderSessionImpl.java:637）
    在com.android.layoutlib.bridge.impl.RenderSessionImpl.render（RenderSessionImpl.java:537）
    在com.android.layoutlib.bridge.Bridge.createSession（Bridge.java:323）
    在com.android.ide.common.rendering.LayoutLibrary.createSession（LayoutLibrary.java:349）
    在com.android.ide.eclipse.adt.internal.editors.layout.gle2.RenderService.createRenderSession(RenderService.java:519)
    在com.android.ide.eclipse.adt.internal.editors.layout.gle2.GraphicalEditorPart.renderWithBridge(GraphicalEditorPart.java:1584)
    在com.android.ide.eclipse.adt.internal.editors.layout.gle2.GraphicalEditorPart.recomputeLayout(GraphicalEditorPart.java:1309)
    在com.android.ide.eclipse.adt.internal.editors.layout.gle2.GraphicalEditorPart.activated(GraphicalEditorPart.java:1066)
    在com.android.ide.eclipse.adt.internal.editors.layout.LayoutEditorDelegate.delegateActivated(LayoutEditorDelegate.java:743)
    在com.android.ide.eclipse.adt.internal.editors.common.CommonXmlEditor.activated(CommonXmlEditor.java:416)
    在com.android.ide.eclipse.adt.internal.editors.layout.gle2.LayoutWindowCoordinator.partActivated(LayoutWindowCoordinator.java:379)
    在org.eclipse.ui.internal.PartService $ 6.run（PartService.java:149）
    在org.eclipse.core.runtime.SafeRunner.run（SafeRunner.java:42）
    在org.eclipse.ui.internal.PartService.partActivated（PartService.java:146）
    在org.eclipse.ui.internal.WorkbenchPage $ 17.run（WorkbenchPage.java:4870）
    在org.eclipse.core.runtime.SafeRunner.run（SafeRunner.java:42）
    在org.eclipse.ui.internal.WorkbenchPage.firePartActivated（WorkbenchPage.java:4867）
    在org.eclipse.ui.internal.WorkbenchPage.access $ 18（WorkbenchPage.java:4846）
    在org.eclipse.ui.internal.WorkbenchPage $ E4PartListener.partActivated（WorkbenchPage.java:210）
    在org.eclipse.e4.ui.internal.workbench.PartServiceImpl $ 3.run（PartServiceImpl.java:241）
    在org.eclipse.core.runtime.SafeRunner.run（SafeRunner.java:42）
    在org.eclipse.e4.ui.internal.workbench.PartServiceImpl.firePartActivated（PartServiceImpl.java:238）
    在org.eclipse.e4.ui.internal.workbench.PartServiceImpl.activate（PartServiceImpl.java:692）
    在org.eclipse.e4.ui.internal.workbench.PartServiceImpl.activate（PartServiceImpl.java:620）
    在org.eclipse.e4.ui.internal.workbench.PartServiceImpl.activate（PartServiceImpl.java:608）
    在org.eclipse.e4.ui.internal.workbench.PartServiceImpl.hidePart（PartServiceImpl.java:1276）
    在org.eclipse.e4.ui.internal.workbench.PartServiceImpl.hidePart（PartServiceImpl.java:1215）
    在org.eclipse.e4.ui.workbench.renderers.swt.StackRenderer.closePart（StackRenderer.java:1218）
    在org.eclipse.e4.ui.workbench.renderers.swt.StackRenderer.access $ 3（StackRenderer.java:1200）
    在org.eclipse.e4.ui.workbench.renderers.swt.StackRenderer $ 12.关闭（StackRenderer.java:1092）
    在org.eclipse.swt.custom.CTabFolder.onMouse（CTabFolder.java:1874）
    在org.eclipse.swt.custom.CTabFolder $ 1.handleEvent（CTabFolder.java:288）
    在org.eclipse.swt.widgets.EventTable.sendEvent（EventTable.java:84）
    在org.eclipse.swt.widgets.Display.sendEvent（Display.java:4353）
    在org.eclipse.swt.widgets.Widget.sendEvent（Widget.java:1061）
    在org.eclipse.swt.widgets.Display.runDeferredEvents（Display.java:4172）
    在org.eclipse.swt.widgets.Display.readAndDispatch（Display.java:3761）
    在org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine $ 9.run（PartRenderingEngine.java:1151）
    在org.eclipse.core.databinding.observable.Realm.runWithDefault（Realm.java:332）
    在org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.run（PartRenderingEngine.java:1032）
    在org.eclipse.e4.ui.internal.workbench.E4Workbench.createAndRunUI（E4Workbench.java:148）
    在org.eclipse.ui.internal.Workbench $ 5.run（Workbench.java:636）
    在org.eclipse.core.databinding.observable.Realm.runWithDefault（Realm.java:332）
    在org.eclipse.ui.internal.Workbench.createAndRunWorkbench（Workbench.java:579）
    在org.eclipse.ui.PlatformUI.createAndRunWorkbench（PlatformUI.java:150）
    在org.eclipse.ui.internal.ide.application.IDEApplication.start（IDEApplication.java:135）
    在org.eclipse.equinox.internal.app.EclipseAppHandle.run（EclipseAppHandle.java:196）
    在org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:134)
    在org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start（EclipseAppLauncher.java:104）
    在org.eclipse.core.runtime.adaptor.EclipseStarter.run（EclipseStarter.java:380）
    在org.eclipse.core.runtime.adaptor.EclipseStarter.run（EclipseStarter.java:235）
    在sun.reflect.NativeMethodAccessorImpl.invoke0（本机方法）
    在sun.reflect.NativeMethodAccessorImpl.invoke（来源不明）
    在sun.reflect.DelegatingMethodAccessorImpl.invoke（来源不明）
    在java.lang.reflect.Method.invoke（来源不明）
    在org.eclipse.equinox.launcher.Main.invokeFramework（Main.java:648）
    在org.eclipse.equinox.launcher.Main.basicRun（Main.java:603）
    在org.eclipse.equinox.launcher.Main.run（Main.java:1465）
    在org.eclipse.equinox.launcher.Main.main（Main.java:1438）
 

解决方案

我重新启动我的日食。它的做工精细了。 问题是SDK未正确装入我的Eclipse。

尝试启动日食否则一旦检查你的SDK管理器是安装了一切与否。

On creating new xml files in a project, rendering issue occur with error log as follows:

java.lang.NullPointerException
    Exception details are logged in Window > Show View > Error Log
    The following classes could not be instantiated:
    - android.support.v7.internal.app.WindowDecorActionBar (Open Class, Show Error Log)
    - android.support.v7.internal.widget.ActionBarContextView (Open Class, Show Error Log)
    - android.support.v7.widget.Toolbar (Open Class, Show Error Log)

...............

java.lang.NullPointerException
    at android.support.v7.internal.widget.ActionBarOverlayLayout.getDecorToolbar(ActionBarOverlayLayout.java:594)
    at android.support.v7.internal.widget.ActionBarOverlayLayout.pullChildren(ActionBarOverlayLayout.java:583)
    at android.support.v7.internal.widget.ActionBarOverlayLayout.onMeasure(ActionBarOverlayLayout.java:368)
    at android.view.View.measure(View.java:17547)
    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5535)
    at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1436)
    at android.widget.LinearLayout.measureVertical(LinearLayout.java:722)
    at android.widget.LinearLayout.onMeasure(LinearLayout.java:613)
    at android.view.View.measure(View.java:17547)
    at android.widget.LinearLayout.measureVertical(LinearLayout.java:875)
    at android.widget.LinearLayout.onMeasure(LinearLayout.java:613)
    at android.view.View.measure(View.java:17547)
    at com.android.layoutlib.bridge.impl.RenderSessionImpl.measureView(RenderSessionImpl.java:637)
    at com.android.layoutlib.bridge.impl.RenderSessionImpl.render(RenderSessionImpl.java:537)
    at com.android.layoutlib.bridge.Bridge.createSession(Bridge.java:323)
    at com.android.ide.common.rendering.LayoutLibrary.createSession(LayoutLibrary.java:349)
    at com.android.ide.eclipse.adt.internal.editors.layout.gle2.RenderService.createRenderSession(RenderService.java:519)
    at com.android.ide.eclipse.adt.internal.editors.layout.gle2.GraphicalEditorPart.renderWithBridge(GraphicalEditorPart.java:1584)
    at com.android.ide.eclipse.adt.internal.editors.layout.gle2.GraphicalEditorPart.recomputeLayout(GraphicalEditorPart.java:1309)
    at com.android.ide.eclipse.adt.internal.editors.layout.gle2.GraphicalEditorPart.activated(GraphicalEditorPart.java:1066)
    at com.android.ide.eclipse.adt.internal.editors.layout.LayoutEditorDelegate.delegateActivated(LayoutEditorDelegate.java:743)
    at com.android.ide.eclipse.adt.internal.editors.common.CommonXmlEditor.activated(CommonXmlEditor.java:416)
    at com.android.ide.eclipse.adt.internal.editors.layout.gle2.LayoutWindowCoordinator.partActivated(LayoutWindowCoordinator.java:379)
    at org.eclipse.ui.internal.PartService$6.run(PartService.java:149)
    at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
    at org.eclipse.ui.internal.PartService.partActivated(PartService.java:146)
    at org.eclipse.ui.internal.WorkbenchPage$17.run(WorkbenchPage.java:4870)
    at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
    at org.eclipse.ui.internal.WorkbenchPage.firePartActivated(WorkbenchPage.java:4867)
    at org.eclipse.ui.internal.WorkbenchPage.access$18(WorkbenchPage.java:4846)
    at org.eclipse.ui.internal.WorkbenchPage$E4PartListener.partActivated(WorkbenchPage.java:210)
    at org.eclipse.e4.ui.internal.workbench.PartServiceImpl$3.run(PartServiceImpl.java:241)
    at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
    at org.eclipse.e4.ui.internal.workbench.PartServiceImpl.firePartActivated(PartServiceImpl.java:238)
    at org.eclipse.e4.ui.internal.workbench.PartServiceImpl.activate(PartServiceImpl.java:692)
    at org.eclipse.e4.ui.internal.workbench.PartServiceImpl.activate(PartServiceImpl.java:620)
    at org.eclipse.e4.ui.internal.workbench.PartServiceImpl.activate(PartServiceImpl.java:608)
    at org.eclipse.e4.ui.internal.workbench.PartServiceImpl.hidePart(PartServiceImpl.java:1276)
    at org.eclipse.e4.ui.internal.workbench.PartServiceImpl.hidePart(PartServiceImpl.java:1215)
    at org.eclipse.e4.ui.workbench.renderers.swt.StackRenderer.closePart(StackRenderer.java:1218)
    at org.eclipse.e4.ui.workbench.renderers.swt.StackRenderer.access$3(StackRenderer.java:1200)
    at org.eclipse.e4.ui.workbench.renderers.swt.StackRenderer$12.close(StackRenderer.java:1092)
    at org.eclipse.swt.custom.CTabFolder.onMouse(CTabFolder.java:1874)
    at org.eclipse.swt.custom.CTabFolder$1.handleEvent(CTabFolder.java:288)
    at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)
    at org.eclipse.swt.widgets.Display.sendEvent(Display.java:4353)
    at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1061)
    at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:4172)
    at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3761)
    at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$9.run(PartRenderingEngine.java:1151)
    at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
    at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.run(PartRenderingEngine.java:1032)
    at org.eclipse.e4.ui.internal.workbench.E4Workbench.createAndRunUI(E4Workbench.java:148)
    at org.eclipse.ui.internal.Workbench$5.run(Workbench.java:636)
    at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
    at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:579)
    at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:150)
    at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:135)
    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:380)
    at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:235)
    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:648)
    at org.eclipse.equinox.launcher.Main.basicRun(Main.java:603)
    at org.eclipse.equinox.launcher.Main.run(Main.java:1465)
    at org.eclipse.equinox.launcher.Main.main(Main.java:1438)

I restarted my eclipse. Its working fine now. The problem is sdk is not loaded properly in my eclipse.

Try to start eclipse otherwise once check your sdk manager is everything installed or not.