magdamiu

// Clean all elements of the recycler
public void clear() {
    emails.clear();
    notifyDataSetChanged();
}

// Add a list of items
public void addAll(List<Email> list) {
    emails.addAll(list);
    notifyDataSetChanged();

magdamiu

<?xml version="1.0" encoding="utf-8"?>
<androidx.swiperefreshlayout.widget.SwipeRefreshLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/swipeContainer"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recyclerViewEmails"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

magdamiu

implementation 'androidx.swiperefreshlayout:swiperefreshlayout:1.1.0'

magdamiu

private void setItemDecorator() {
    RecyclerView.ItemDecoration itemDecoration = new
            DividerItemDecoration(this, DividerItemDecoration.VERTICAL);
    recyclerViewEmails.addItemDecoration(itemDecoration);
}

magdamiu

public class EmailDiffCallback extends DiffUtil.Callback {

    private List<Email> oldList;
    private List<Email> newList;

    public EmailDiffCallback(List<Email> oldList, List<Email> newList) {
        this.oldList = oldList;
        this.newList = newList;
    }

magdamiu

// NOT OK
void onNewEmailsArrivedNotRecommended(List<Email> newEmails) {
    emailAdapter.setEmails(newEmails);
    emailAdapter.notifyDataSetChanged();
}

// OK
void onNewDataArrivedFastRendering(List<Email> newEmails) {
    List<Email> oldEmails = emailAdapter.getEmails();
    DiffUtil.DiffResult result = DiffUtil.calculateDiff(new EmailDiffCallback(oldEmails, newEmails));

magdamiu

private void setEmailsAdapter() {
    recyclerViewEmails.setAdapter(new EmailAdapter(this, emails));
}

private void displayEmailsList() {
    // data source - checked
    inbox();

    // layout manager - checked
    setEmailsLayoutManager();

magdamiu

public class EmailAdapter extends RecyclerView.Adapter<EmailViewHolder> {
    private List<Email> emails;
    private Context context;

    public EmailAdapter(Context context, List<Email> emails) {
        this.emails = emails;
        this.context = context;
    }

    // creates the items and add them to the RecyclerView, just the layout

magdamiu

public class EmailViewHolder extends RecyclerView.ViewHolder{

    private final TextView textViewFrom, textViewSubject, textViewBody;
    private final LinearLayout linearLayoutEmail;

    public EmailViewHolder(@NonNull View itemView) {
        super(itemView);

        textViewFrom = itemView.findViewById(R.id.textViewFrom);
        textViewSubject = itemView.findViewById(R.id.textViewSubject);

magdamiu

private void setEmailsLayoutManager() {
      recyclerViewEmails.setLayoutManager(new LinearLayoutManager(this));
}