How to Sort 2D ArrayList by Only the First Element [duplicate]

Answer 1

For diversity Why dont you just use a HashMap unless you want duplicate keys. the key would be name and the value would be an ArrayList of numbers

String name="John";

ArrayList phonenumbers=new ArrayList();

phonenumbers.add("80925887");
phonenumbers.add("+166476654");

TreeMap tm=new TreeMap();

tm.put(name, phonenumbers);