title: Failed to find style 'floatingActionButtonStyle' in current theme
body: <p>I'm newbie to android development so i start the simple project that came with android studio "hello world " but it give this problem :</p>
  
  <p><strong>Failed to find style 'floatingActionButtonStyle' in current theme</strong> 
  I have android studio 3.1.3 x86</p>
  
  <p>also my SDK Version from the build.gradle file  is  28 </p>
  
  <p>and this is the <strong>activity_main.xml</strong>:</p>
  
  <pre><code>    &lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
      xmlns:app="http://schemas.android.com/apk/res-auto"
      xmlns:tools="http://schemas.android.com/tools"
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      tools:context=".MainActivity"&gt;
  
      &lt;android.support.design.widget.AppBarLayout
          android:layout_width="match_parent"
          android:layout_height="wrap_content"
          android:theme="@style/AppTheme.AppBarOverlay"&gt;
  
          &lt;android.support.v7.widget.Toolbar
              android:id="@+id/toolbar"
              android:layout_width="match_parent"
              android:layout_height="?attr/actionBarSize"
              android:background="?attr/colorPrimary"
              app:popupTheme="@style/AppTheme.PopupOverlay" /&gt;
  
      &lt;/android.support.design.widget.AppBarLayout&gt;
  
      &lt;include layout="@layout/content_main" /&gt;
  
      &lt;android.support.design.widget.FloatingActionButton
          android:id="@+id/fab"
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:layout_gravity="bottom|end"
          android:layout_margin="@dimen/fab_margin"
          app:srcCompat="@android:drawable/ic_dialog_email" /&gt;
  
  &lt;/android.support.design.widget.CoordinatorLayout&gt;
  </code></pre>
  
  <p>and this is my <strong>content_main.xml</strong>:</p>
  
  <pre><code>        &lt;?xml version="1.0" encoding="utf-8"?&gt;
      &lt;android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
          xmlns:app="http://schemas.android.com/apk/res-auto"
          xmlns:tools="http://schemas.android.com/tools"
          android:layout_width="match_parent"
          android:layout_height="match_parent"
          app:layout_behavior="@string/appbar_scrolling_view_behavior"
          tools:context=".MainActivity"
          tools:showIn="@layout/activity_main"&gt;
  
          &lt;TextView
              android:layout_width="wrap_content"
              android:layout_height="wrap_content"
              android:text="Hello World!"
              app:layout_constraintBottom_toBottomOf="parent"
              app:layout_constraintLeft_toLeftOf="parent"
              app:layout_constraintRight_toRightOf="parent"
              app:layout_constraintTop_toTopOf="parent" /&gt;
      &lt;/android.support.constraint.ConstraintLayout&gt;
  </code></pre>
  
  <p>and this is my <strong>AndroidManifest.xml</strong>:</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="com.example.admin.myapplication"&gt;
  
      &lt;application
          android:allowBackup="true"
          android:icon="@mipmap/ic_launcher"
          android:label="@string/app_name"
          android:roundIcon="@mipmap/ic_launcher_round"
          android:supportsRtl="true"
          android:theme="@style/AppTheme"&gt;
          &lt;activity
              android:name=".MainActivity"
              android:label="@string/app_name"
              android:theme="@style/AppTheme.NoActionBar"&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;
  
  &lt;/manifest&gt;
  </code></pre>