fab追加

app/src/main/res/layout/activity_main.xml

@@ -34,4 +34,17 @@
         app:layout_constraintStart_toStartOf="parent"
         app:menu="@menu/bottom_nav_menu" />
 
+    <com.google.android.material.floatingactionbutton.FloatingActionButton
+        android:id="@+id/scanFab"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_marginEnd="24dp"
+        android:layout_marginBottom="24dp"
+        android:clickable="true"
+        app:layout_constraintBottom_toTopOf="@+id/bottom_nav"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:srcCompat="@drawable/ic_baseline_add_24" />
+
+
+
 </androidx.constraintlayout.widget.ConstraintLayout>