How to display Contacts in alphabetic order in Listview [closed]

Answer 1

I have added Alphabetic headers to contact list

new ReadContactTask(context, showProgressDialog,new OnContactReadListener() {
            @Override
            public void onContactRead(List dummyList) {

                ArrayList latestPhoneContacts = new ArrayList<>();

                if(dummyList!=null && dummyList.size()>0)
                {
                    tvNoResult.setVisibility(View.GONE);

                    for(ContactItem contactItem : dummyList){
                        String contactNameInCapital = "";
                        if(contactItem.getContactName()!=null && contactItem.getContactName().length()>2){
                            contactNameInCapital = contactItem.getContactName().substring(0,1).toUpperCase();

                            if(contactNameInCapital.charAt(0) != previousContact.charAt(0))
                            {
                                latestPhoneContacts.add(new ContactItem(contactNameInCapital.substring(0,1)));
                                latestPhoneContacts.add(contactItem);
                            }
                            else
                            {
                                latestPhoneContacts.add(contactItem);
                            }

                            previousContact = contactNameInCapital;
                        }
                    }
                    if(latestPhoneContacts!=null && latestPhoneContacts.size()>0)
                        contactListAdapter.addItems(latestPhoneContacts);
                }
            }

            @Override
            public void onContactEmpty() {

            }
        }).execute();

where

private String previousContact ="Zee";