findViewById cannot find RecyclerView in activity_main

I can find other layouts using id , but i am unable to find RecyclerView

MainActivity

protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

    GridView gridView=findViewById(R.id.unitsGrid);
    ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,
            android.R.layout.simple_list_item_1, units);

    recyclerView= findViewById(R.id.);

}

activiy_main.xml

<androidx.appcompat.widget.LinearLayoutCompat 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"
android:orientation="vertical"
tools:context=".Activities.MainActivity">
<androidx.recyclerview.widget.RecyclerView
    android:id="@+id/recyclerView"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

</androidx.recyclerview.widget.RecyclerView></androidx.appcompat.widget.LinearLayoutCompat>