How to implement a view holder?

        @Override

        public View getView(int position, View v, ViewGroup parent) {

            // Keeps reference to avoid future findViewById()

            ContactsViewHolder viewHolder;

    

            if (v == null) {

                LayoutInflater li = (LayoutInflater) getContext().getSystemService(

                        Context.LAYOUT_INFLATER_SERVICE);

                v = li.inflate(R.layout.contact_row, parent, false);

    

                viewHolder = new ContactsViewHolder();

                viewHolder.txName = (TextView) v.findViewById(R.id.tvName);

                viewHolder.txEmails = (TextView) v.findViewById(R.id.tvEmails);

                viewHolder.txPhones = (TextView) v.findViewById(R.id.tvNumbers);

    

                v.setTag(viewHolder);

            } else {

                viewHolder = (ContactsViewHolder) v.getTag();

            }

    

            Contact contact = contacts.get(position);

            if (contact != null) {

                viewHolder.txName.setText(contact.getName());

                viewHolder.txEmails.setText(contact.getEmails().toString());

                viewHolder.txPhones.setText(contact.getNumbers().toString());

            }

            return v;

        }

    

        static class ContactsViewHolder {

            TextView txName;

            TextView txEmails;

            TextView txPhones;

        }

    }