You need to use a Theme.AppCompat theme (or descendant) with this activity. _Activity

一箫一剑平生意，负尽狂名十五年。这篇文章主要讲述You need to use a Theme.AppCompat theme (or descendant) with this activity.相关的知识，希望能为你提供帮助。
这几天想给自己的后端程序搞个前端架子，准备用安卓来实现，现学现用，直接京东搜索关于安卓的热门书籍，下个PDF搞起。
销量第一的是《第一行代码 android 第2版》，不错，销量第一，拿来入门应该足够了，不过这书是基于 Android 7 的，谷歌真是神速，到今天 Android 9 都已经发布了
花了半天直接看到了第二章，虽然是安卓萌新，但也勉强实现了手机上的界面 DEMO，真刺激啊。
【You need to use a Theme.AppCompat theme (or descendant) with this activity.】先运行一下瞧瞧，先点个弹窗试试。

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根据我菜鸟般的编程经验，这不过是个小问题，后来知道了，这的确是个小问题，但这个问题也让我整整懵逼了一天。
先贴下报错日志：

01-03 22:38:01.430 11502-11502/com.example.activitylifecycletest E/AndroidRuntime: FATAL EXCEPTION: main Process: com.example.activitylifecycletest, PID: 11502 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.activitylifecycletest/com.example.activitylifecycletest.DialogActivity}: java.lang.IllegalStateException: You need to use a Theme.AppCompat theme (or descendant) with this activity. at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476) at android.app.ActivityThread.-wrap11(ActivityThread.java) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:148) at android.app.ActivityThread.main(ActivityThread.java:5417) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) at de.robv.android.xposed.XposedBridge.main(XposedBridge.java:103) Caused by: java.lang.IllegalStateException: You need to use a Theme.AppCompat theme (or descendant) with this activity. at android.support.v7.app.AppCompatDelegateImpl.createSubDecor(AppCompatDelegateImpl.java:555) at android.support.v7.app.AppCompatDelegateImpl.ensureSubDecor(AppCompatDelegateImpl.java:518) at android.support.v7.app.AppCompatDelegateImpl.setContentView(AppCompatDelegateImpl.java:466) at android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:140) at com.example.activitylifecycletest.DialogActivity.onCreate(DialogActivity.java:11) at android.app.Activity.performCreate(Activity.java:6285) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1108) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476) at android.app.ActivityThread.-wrap11(ActivityThread.java) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:148) at android.app.ActivityThread.main(ActivityThread.java:5417) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) at de.robv.android.xposed.XposedBridge.main(XposedBridge.java:103)

You need to use a Theme.AppCompat theme (or descendant) with this activity.，瞅见了，这句话很好理解，不就是让我换个 AppCompat theme 然后继续使用嘛，小Easy。
一开始呢，书中的代码是下面这样的：