java – How to user RecyclerView inside of NavigationDrawer

I want to use a RecyclerView inside of a NavigationDrawer but I’m not sure how to do it. This is what i want to do:

I want to have a List inside the Navigation Drawer where you can add entries with a Button/Textfield and delete them by swiping. If there’s a better way to do this then with NavigationDrawer and RecyclerView, please let me know. The List will have a limited amound of entries, so Performance should not be an issue.

Here is what i’ve got so far:

MainActivity.java

public class MainActivity extends AppCompatActivity {
 ActionBarDrawerToggle toggle=null;
 RecyclerView recyclerView;
 RecyclerAdapter recyclerAdapter;

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

        DrawerLayout drawerLayout=findViewById(R.id.drawerLayout);

        toggle= new ActionBarDrawerToggle(this,drawerLayout,R.string.drawerOpen,R.string.drawerClose);
        drawerLayout.addDrawerListener(toggle);
        toggle.syncState();
        super.getSupportActionBar().setDisplayHomeAsUpEnabled(true);
        super.getSupportActionBar().setHomeButtonEnabled(true);
        recyclerView=findViewById(R.id.recyclerView);
        recyclerAdapter= new RecyclerAdapter();

        recyclerView.setLayoutManager(new LinearLayoutManager(this));
        recyclerView.setAdapter(recyclerAdapter);
    }


    @Override
    public boolean onOptionsItemSelected(@NonNull MenuItem item) {
        if(toggle.onOptionsItemSelected(item)){
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}

RecyclerAdapter.java

public class RecyclerAdapter extends RecyclerView.Adapter<RecyclerAdapter.ViewHolder>{


    @NonNull
    @Override
    public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        LayoutInflater layoutInflater=LayoutInflater.from(parent.getContext());
        View view = layoutInflater.inflate(R.layout.row_item,parent,false);
        ViewHolder viewHolder=new ViewHolder(view);
        return viewHolder;
    }

    @Override
    public void onBindViewHolder(@NonNull ViewHolder holder, int position) {

    }

    @Override
    public int getItemCount() {
        return 10;
    }

    class ViewHolder extends RecyclerView.ViewHolder{

        ImageView imageView;
        TextView t_Title,t_Description;
        public ViewHolder(@NonNull View itemView) {


            super(itemView);
            imageView=itemView.findViewById(R.id.imageView);
            t_Description=itemView.findViewById(R.id.t_Description);
            t_Title=itemView.findViewById(R.id.t_Title);
        }
    }

}


activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.drawerlayout.widget.DrawerLayout 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:id="@+id/drawerLayout"
    android:layout_height="match_parent"
    tools:context=".MainActivity">
    <androidx.constraintlayout.widget.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

    <com.google.android.material.navigation.NavigationView
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        app:headerLayout="@layout/nav_header"

        android:layout_gravity="start"
        android:fitsSystemWindows="true"/>

</androidx.drawerlayout.widget.DrawerLayout>

nav_header.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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">

    <Button
        android:id="@+id/button2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="30dp"
        android:layout_marginEnd="5dp"
        android:text="Button"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <EditText
        android:id="@+id/editTextTextPersonName"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="5dp"
        android:layout_marginEnd="5dp"
        android:ems="10"
        android:inputType="textPersonName"
        android:minHeight="48dp"
        android:text="Name"
        app:layout_constraintBottom_toBottomOf="@+id/button2"
        app:layout_constraintEnd_toStartOf="@+id/button2"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="@+id/button2" />

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recyclerView"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:layout_marginStart="1dp"
        android:layout_marginTop="1dp"
        android:layout_marginEnd="1dp"
        android:layout_marginBottom="1dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/editTextTextPersonName" />

</androidx.constraintlayout.widget.ConstraintLayout>

row_item.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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="wrap_content">

    <ImageView
        android:id="@+id/imageView"
        android:layout_width="48dp"
        android:layout_height="48dp"
        android:layout_marginStart="16dp"
        android:layout_marginTop="16dp"
        android:layout_marginBottom="16dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        tools:srcCompat="@tools:sample/avatars" />

    <TextView
        android:id="@+id/t_Title"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="16dp"
        android:layout_marginEnd="5dp"
        android:text="TextView"
        android:textSize="14sp"
        app:layout_constraintBottom_toTopOf="@+id/t_Description"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toEndOf="@+id/imageView"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@+id/t_Description"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginEnd="5dp"
        android:text="TextView"
        android:textSize="10sp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="@+id/t_Title"
        app:layout_constraintTop_toBottomOf="@+id/t_Title" />
</androidx.constraintlayout.widget.ConstraintLayout>

So far I get a NullPointerException: java.lang.NullPointerException: Attempt to invoke virtual method 'void androidx.recyclerview.widget.RecyclerView.setLayoutManager(androidx.recyclerview.widget.RecyclerView$LayoutManager)' on a null object reference
I’m pretty sure thats because of the LayoutInflater because the RecyclerView is not part of the main activity but i don’t know how to fix it.

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