getting Report unnecessary cast expressions MainActivity.onCreate

Question

public class MainActivity extends AppCompatActivity {

    ArrayList<Books_item> items = new ArrayList<>();
    BooksAdapter adapter;
    ListView listView;

private DrawerLayout nDrawerLayout;
private ActionBarDrawerToggle nToggle;

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

        nDrawerLayout=(DrawerLayout) findViewById(R.id.drawerlayout);
        nToggle= new ActionBarDrawerToggle(this,nDrawerLayout,R.string.open,R.string.close);

        nDrawerLayout.addDrawerListener(nToggle);
        nToggle.syncState();
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>

<androidx.drawerlayout.widget.DrawerLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/drawerlayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">
<!--    tools:context=".MainActivity">-->
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">

   <View
       android:layout_width="match_parent"
       android:layout_height="2dp"
       android:background="#ca1515"
       />

    <ListView
        android:id="@+id/book_list"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>
    </LinearLayout>

<android.support.design.widget.NavigationView
    android:layout_width="wrap_content"
    android:layout_height="match_parent"
    app:menu="@menu/navigation_menu"
    android:layout_gravity="start">
</android.support.design.widget.NavigationView>

</androidx.drawerlayout.widget.DrawerLayout>

i'm trying to add fragment menu ,but i have this bug appear after run there's no error appear when i build

and why i have (DrawerLayout) as unused

Report unnecessary cast expressions

i tried add >import com.your.package.R

Answer 1

There is a similar question with an explanation - No need to cast the result of findViewById?

Solution

In your code no need to cast the result of findViewById API - see below

nDrawerLayout = findViewById(R.id.drawerlayout);