Firebase one to one chat

Question

I am creating a simple chat application in android with Firebase as the backend.

ref3.addValueEventListener(new ValueEventListener() { @Override public void onDataChange(DataSnapshot snapshot) { Map<String, Object> users = (Map<String, Object>) snapshot.getValue(); System.out.println(users.values().toString()); Set s = users.entrySet(); Iterator itr = s.iterator(); while (itr.hasNext()) { Map.Entry m = (Map.Entry) itr.next(); m.getKey(); String myval = m.getValue().toString(); String spmyval[] = myval.split(", "); System.out.println(spmyval[0] + " <-sp0 sp1-> " + spmyval[1]); list=new ArrayList(); a1 = spmyval[0].split("="); Cursor cur = getContentResolver().query( ContactsContract.Contacts.CONTENT_URI, null, null, null, null); if (cur.getCount() > 0) { while (cur.moveToNext()) { // read id String id = cur.getString(cur .getColumnIndex(ContactsContract.Contacts._ID)); /** read names **/ displayName = cur .getString(cur .getColumnIndex(ContactsContract.Contacts.DISPLAY_NAME)); System.out.println("DISPLAYNAMESssss:!!!!!!!!!!!!!!"+displayName+"::::::::"); /** Phone Numbers **/ Cursor pCur = getContentResolver().query( ContactsContract.CommonDataKinds.Phone.CONTENT_URI, null, ContactsContract.CommonDataKinds.Phone.CONTACT_ID + " = ?", new String[]{id}, null); String typeStr = null; int i=0; while (pCur.moveToNext()) { num = pCur .getString(pCur .getColumnIndex(ContactsContract.CommonDataKinds.Phone.NUMBER)); number1=new String[]{num}; Log.e("Number by pavan",i +" " + number1[i]); typeStr = pCur .getString(pCur .getColumnIndex(ContactsContract.CommonDataKinds.Phone.TYPE)); if(a1[1].equals(number1[i].replaceAll("[^\\d.]", ""))) { Log.e("COMMON:", a1[1]); i++; } } pCur.close(); } } 

I have a registration page configured in such a way that user contact information is stored in a UID (genrated by firebase). I got shared contacts using the code above. I require the user to send a push message to this total. However, I cannot find a way to recover the UID to which the number belongs. I get a shared number to get a list of friends who use my app. Therefore, I am confused if I need to hard code this or write in the API. Please give me an example if anyone has a solution