Cannot resolve Symbol 'TextView' / Cannot resolve Symbol 'Button'

TextView factLabel = (TextView) findViewById(R.id.factTextView);
Button myButton = (Button) findViewById(R.id.showFactButton);

 <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="I am just so sexy lately."
        android:id="@+id/factTextView"
        android:textSize="24sp"
        android:textIsSelectable="true"
        android:textColor="@android:color/white"
        android:textAlignment="center"
        android:layout_centerVertical="true"
        android:layout_alignParentRight="true"
        android:layout_alignParentEnd="true" />

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="See more"
        android:id="@+id/showFactButton"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        android:background="@android:color/white" />