How to remove Duplicate Contact in Android Studio display with ListView

Question

I'm writing a program to display my contact list in hp, but I always get duplicate contacts. Where is my code not correct?

display my code run

This is my code

Here I'm confused how to make a filter where duplicate contacts do not need to be added to the listview:

contactModelArrayList = new ArrayList<>();
String[] projection = new String[]{
        ContactsContract.CommonDataKinds.Phone.NUMBER,
        ContactsContract.CommonDataKinds.Phone.DISPLAY_NAME
};
Cursor phones = getContentResolver().query(ContactsContract.CommonDataKinds.Phone.CONTENT_URI,
        projection,
        ContactsContract.Contacts.IN_VISIBLE_GROUP + " = '1'",
        null,
        ContactsContract.CommonDataKinds.Phone.DISPLAY_NAME+" COLLATE LOCALIZED ASC");

while (phones.moveToNext())
{
    String name=phones.getString(phones.getColumnIndex(ContactsContract.CommonDataKinds.Phone.DISPLAY_NAME));
    String phoneNumber = phones.getString(phones.getColumnIndex(ContactsContract.CommonDataKinds.Phone.NUMBER));

    ContactModel contactModel = new ContactModel();
    contactModel.setName(name);
    contactModel.setNumber(phoneNumber);

    contactModelArrayList.add(contactModel);

}

phones.close();

contactAllAdapter = new ContactAllAdapter(this,contactModelArrayList);
listView.setAdapter(contactAllAdapter);

And this for file ContactAll Adapter

public class ContactAllAdapter extends BaseAdapter {
    private Context context;
    private ArrayList<ContactModel> contactModels;
    private String kode, nomor;

    public ContactAllAdapter(Context context, ArrayList<ContactModel> contactModels) {
        this.context = context;
        this.contactModels = contactModels;
    }

    @Override
    public int getViewTypeCount() {
        if(getCount() > 0){
            return getCount();
        }else{
            return super.getViewTypeCount();
        }
    }

    @Override
    public int getCount() {
        return contactModels.size();
    }

    @Override
    public Object getItem(int position) {
        return contactModels.get(position);
    }

    @Override
    public long getItemId(int position) {
        return 0;
    }

    @Override
    public View getView(final int position, View convertView, ViewGroup parent) {
        final ViewHolder holder;

        if (convertView == null) {
            holder = new ViewHolder();
            LayoutInflater inflater = (LayoutInflater) context
                    .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            convertView = inflater.inflate(R.layout.row_all_contact, null, true);

            holder.cname = convertView.findViewById(R.id.contact_name);
            holder.cnumber = convertView.findViewById(R.id.contact_number);
            holder.cinvite = convertView.findViewById(R.id.contact_invite);

            convertView.setTag(holder);
        }else {
            // the getTag returns the viewHolder object set as a tag to the view
            holder = (ViewHolder)convertView.getTag();
        }

        holder.cname.setText(contactModels.get(position).getName());
        holder.cnumber.setText(contactModels.get(position).getNumber());

        holder.cinvite.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                final String appPackageName = context.getPackageName();
                String text = context.getResources().getString(R.string.share_app_text);
                String link = "https://play.google.com/store/apps/details?id=" + appPackageName;//app link is auto generated by using package name

                Intent sendIntent = new Intent(Intent.ACTION_VIEW);
                sendIntent.putExtra("sms_body", text+"\n\n"+link);
                sendIntent.putExtra("address", contactModels.get(position).getNumber());
                sendIntent.setType("vnd.android-dir/mms-sms");
                context.startActivity(sendIntent);
            }
        });

        return convertView;
    }

    private class ViewHolder {

        protected TextView cname, cnumber;
        protected Button cinvite;
    }
}

And this file class of Contact Model

public class ContactModel {

    private String name, number;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getNumber() {
        return number;
    }

    public void setNumber(String number) {
        this.number = number;
    }
}

Answer 1

In your activity (first piece of code):

    Set<ContactModel> contactModelSet = new HashSet<>();

    // the same ...

    ArrayList<ContactModel> contactModelArrayList = new ArrayList<>(contactModelSet);

    contactAllAdapter = new ContactAllAdapter(this,contactModelArrayList);

In ContactModel class:

@Override
public int hashCode() {
    // calculate hash code if needed, something like this
    return this.name.hashCode() + this.number.hashCode();
}

@Override
public boolean equals(Object obj) {
    if (obj instanceof ContactModel) {
        ContactModel cm = (ContactModel) obj;
        return this.getName().equals(cm.getName()) && this.getNumber().equals(cm.getNumber());
    }
    return false;
}

@Override
public int compareTo(ContactModel o) {
    // implement if you need to order
    // don't know your criteria
    // must return -1, 0, 1 if this is less, equal or greater than o
    return 0;
}