title: "You need to use a Theme.AppCompat theme (or descendant) with this activity."
body: <p>I am new to Android programming and I am running into a simple XML issue. I am in the process of trying to make one of my empty activities into a fullscreen activity. I tried adding this line of code 
       android:theme="@android:style/Theme.NoTitleBar.Fullscreen"
   into my android manifest file, which ended up making my app crash on start. </p>
  
  <p>If this also helps, my java file for the affected activity extends the AppCompatActivity. I saw some other posts that mentioned that this would create issues but I have not been able to fix my problem.</p>
  
  <p>Please help me fix this issue while still making the activity fullscreen. Any help is appreciated. Thanks!</p>
  
  <p>XML</p>
  
  <pre><code>&lt;application
      android:allowBackup="true"
      android:icon="@mipmap/ic_launcher"
      android:roundIcon="@mipmap/ic_launcher_round"
      android:supportsRtl="true"
      android:theme="@style/Theme.AppCompat.Light"&gt;
      &lt;activity android:name=".MainActivity"
          android:label="Marks Calculator"&gt;
          &lt;intent-filter&gt;
              &lt;action android:name="android.intent.action.MAIN" /&gt;
  
              &lt;category android:name="android.intent.category.APP_CALCULATOR" /&gt;
          &lt;/intent-filter&gt;
      &lt;/activity&gt;
      &lt;activity android:name=".Home_Activity"
          android:label="Finite Time Manager"&gt;
          &lt;intent-filter&gt;
              &lt;action android:name="android.intent.action.MAIN" /&gt;
  
              &lt;category android:name="android.intent.category.HOME" /&gt;
          &lt;/intent-filter&gt;
      &lt;/activity&gt;
      &lt;activity
          android:name=".Welcome_Activity"
          android:theme="@android:style/Theme.NoTitleBar.Fullscreen"&gt;
          &lt;intent-filter&gt;
              &lt;action android:name="android.intent.action.MAIN" /&gt;
  
              &lt;category android:name="android.intent.category.LAUNCHER" /&gt;
          &lt;/intent-filter&gt;
          &lt;/activity&gt;
  &lt;/application&gt;
  </code></pre>
  
  <p></p>
  
  <p>Error logcat</p>
  
  <pre><code>12-22 12:21:30.214 32475-32475/com.managergmail.time.finite.finitemanager02 E/AndroidRuntime: FATAL EXCEPTION: main
      Process: com.managergmail.time.finite.finitemanager02, PID: 32475
      java.lang.RuntimeException: Unable to start activity ComponentInfo{com.managergmail.time.finite.finitemanager02/com.managergmail.time.finite.finitemanager02.Welcome_Activity}: java.lang.IllegalStateException: You need to use a Theme.AppCompat theme (or descendant) with this activity.
      at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2581)
      at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2647)
      at android.app.ActivityThread.-wrap11(ActivityThread.java)
      at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1502)
      at android.os.Handler.dispatchMessage(Handler.java:111)
      at android.os.Looper.loop(Looper.java:207)
      at android.app.ActivityThread.main(ActivityThread.java:5763)
      at java.lang.reflect.Method.invoke(Native Method)
      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:888)
      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:749)
      Caused by: java.lang.IllegalStateException: You need to use a Theme.AppCompat theme (or descendant) with this activity.
      at android.support.v7.app.AppCompatDelegateImplV9.createSubDecor(AppCompatDelegateImplV9.java:359)
      at android.support.v7.app.AppCompatDelegateImplV9.ensureSubDecor(AppCompatDelegateImplV9.java:328)
      at android.support.v7.app.AppCompatDelegateImplV9.setContentView(AppCompatDelegateImplV9.java:289)
      at android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:140)
      at com.managergmail.time.finite.finitemanager02.Welcome_Activity.onCreate(Welcome_Activity.java:17)
      at android.app.Activity.performCreate(Activity.java:6280)
      at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1116)
      at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2534)
      at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2647)
      at android.app.ActivityThread.-wrap11(ActivityThread.java)
      at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1502)
      at android.os.Handler.dispatchMessage(Handler.java:111)
      at android.os.Looper.loop(Looper.java:207)
      at android.app.ActivityThread.main(ActivityThread.java:5763)
      at java.lang.reflect.Method.invoke(Native Method)
      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:888)
      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:749)
  </code></pre>