import java.util.*; public class LearnTreeMap { public static void main(String[] args) { Map numbers = new TreeMap<>(); numbers.put("one",1); numbers.put("five",5); numbers.put("two",2); numbers.put("three",3); numbers.put("eight",8); //numbers.put("two",22); ------> override the old value //numbers.putIfAbsent("two",22); System.out.println(numbers); for(Map.Entry e: numbers.entrySet()){ System.out.println(e); } // for(Map.Entry e: numbers.entrySet()){ // System.out.println(e.getKey()); // System.out.println(e.getValue()); // } for(String key: numbers.keySet()){ System.out.println(key); } System.out.println(numbers.containsKey("one")); numbers.replace("one",1,11); System.out.println(numbers); } }