androidstudio的问题

Question

我是android开发的新手，比我安装android studio并且在使用视图或活动时我收到以下错误：

enter image description here

the following classes could not be instantiated 
- android.support.design.widget.CoordinatorLayout 
- android.support.design.widget.AppBarLayout  
- android.support.design.widget.FloatingActionButton 

Expections Details:
java.lang.IllegalArgumentException: You need to use a Theme.AppCompat theme (or descendant) with the design library.
    at android.support.design.widget.ThemeUtils.checkAppCompatTheme(ThemeUtils.java:34)
    at android.support.design.widget.CoordinatorLayout.(CoordinatorLayout.java:178)
    at android.support.design.widget.CoordinatorLayout.(CoordinatorLayout.java:172)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:422)
    at org.jetbrains.android.uipreview.ViewLoader.createNewInstance(ViewLoader.java:458)
    at org.jetbrains.android.uipreview.ViewLoader.loadClass(ViewLoader.java:170)
    at org.jetbrains.android.uipreview.ViewLoader.loadView(ViewLoader.java:103)
    at com.android.tools.idea.rendering.LayoutlibCallbackImpl.loadView(LayoutlibCallbackImpl.java:190)
    at android.view.BridgeInflater.loadCustomView(BridgeInflater.java:247)
    at android.view.BridgeInflater.createViewFromTag(BridgeInflater.java:171)
    at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:704)
    at android.view.LayoutInflater.inflate(LayoutInflater.java:492)
    at android.view.LayoutInflater.inflate(LayoutInflater.java:394)
    at com.android.layoutlib.bridge.impl.RenderSessionImpl.inflate(RenderSessionImpl.java:223)
    at com.android.layoutlib.bridge.Bridge.createSession(Bridge.java:426)
    at com.android.ide.common.rendering.LayoutLibrary.createSession(LayoutLibrary.java:350)
    at com.android.tools.idea.rendering.RenderTask$2.compute(RenderTask.java:510)
    at com.android.tools.idea.rendering.RenderTask$2.compute(RenderTask.java:498)
    at com.intellij.openapi.application.impl.ApplicationImpl.runReadAction(ApplicationImpl.java:888)
    at com.android.tools.idea.rendering.RenderTask.createRenderSession(RenderTask.java:498)
    at com.android.tools.idea.rendering.RenderTask.access$600(RenderTask.java:72)
    at com.android.tools.idea.rendering.RenderTask$3.call(RenderTask.java:610)
    at com.android.tools.idea.rendering.RenderTask$3.call(RenderTask.java:607)
    at com.android.tools.idea.rendering.RenderService.runRenderAction(RenderService.java:366)
    at com.android.tools.idea.rendering.RenderTask.render(RenderTask.java:607)
    at com.android.tools.idea.rendering.RenderTask.render(RenderTask.java:629)
    at com.intellij.android.designer.designSurface.AndroidDesignerEditorPanel$6.run(AndroidDesignerEditorPanel.java:480)
    at com.intellij.util.ui.update.MergingUpdateQueue.execute(MergingUpdateQueue.java:320)
    at com.intellij.util.ui.update.MergingUpdateQueue.execute(MergingUpdateQueue.java:310)
    at com.intellij.util.ui.update.MergingUpdateQueue$2.run(MergingUpdateQueue.java:254)
    at com.intellij.util.ui.update.MergingUpdateQueue.flush(MergingUpdateQueue.java:269)
    at com.intellij.util.ui.update.MergingUpdateQueue.flush(MergingUpdateQueue.java:227)
    at com.intellij.util.ui.update.MergingUpdateQueue.run(MergingUpdateQueue.java:217)
    at com.intellij.util.concurrency.QueueProcessor.runSafely(QueueProcessor.java:238)
    at com.intellij.util.Alarm$Request$1.run(Alarm.java:351)
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)

有人可以帮忙吗？ P.S。抱歉我的英文

Answer 1

我遇到了同样的问题，尝试更改API（您在layout上使用的是API 23），尝试将其置于API 21，如果它不起作用尝试重新启动Android Studio

这就是你改变API的方式

有关详细信息，请查看此question和此one

Answer 2

只需将您的Android工作室更新为最新版本，也可以通过以下方式更新您的sdk：Choose File > Settings > Appearance & Behavior > System Settings > Updates.