title: Error inflating class android.support.design.widget.FloatingActionButton on Androidx library
body: <p>I added a simple widget button to my Android activity:</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
      android:theme="@style/Theme.AppCompat"
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      android:layout_marginLeft="4sp"
      android:layout_marginTop="1sp"
      android:layout_marginRight="4sp"
      android:orientation="vertical"&gt;
  
      &lt;ListView
          android:id="@+id/orders_list"
          android:layout_width="match_parent"
          android:layout_height="match_parent"
          android:clickable="true"
          android:focusable="auto" /&gt;
  
      &lt;android.support.design.widget.FloatingActionButton
          android:id="@+id/fab"
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:layout_gravity="end|bottom"
          android:src="@drawable/ic_add"
          android:contentDescription="fazer pedido"
          android:layout_margin="16dp" /&gt;
  
  &lt;/LinearLayout&gt;
  </code></pre>
  
  <p>Then I get</p>
  
  <pre><code>android.view.InflateException: Binary XML file line #18: Binary XML file line #18: Error inflating class android.support.design.widget.FloatingActionButton
  </code></pre>
  
  <p>Here are my gradle dependencies</p>
  
  <pre><code>dependencies {
      implementation fileTree(dir: 'libs', include: ['*.jar'])
      implementation 'com.squareup.okhttp3:okhttp:3.12.1'
      implementation 'org.json:json:20190722'
      implementation 'com.fasterxml.jackson.core:jackson-databind:2.10.1'
      implementation 'androidx.appcompat:appcompat:1.1.0'
      implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
      implementation 'androidx.legacy:legacy-support-v4:1.0.0'
      implementation 'androidx.lifecycle:lifecycle-extensions:2.0.0'
      testImplementation 'junit:junit:4.12'
      androidTestImplementation 'androidx.test.ext:junit:1.1.0'
      androidTestImplementation 'androidx.test.espresso:espresso-core:3.1.1'
  }
  </code></pre>
  
  <p>I tried all solutions here on stackoverflow. Some mentions using backgroundTint but I don't even use that. Some others mention about v7 compact library, but I'm using androidx one. So this problem looks like a new one, different from others</p>
  
  <p>Don't know if it helps but this is my activity:</p>
  
  <pre><code>public class OrdersActivity extends AppCompatActivity implements AbsListView.OnScrollListener{
  protected void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.activity_orders);
  </code></pre>