import java.util.*; 
 
public class HashMapDemo 
{ 
 public static void main(String[] args) 
 { 
  HashMap<String, Integer> hm = new HashMap<>(); 
  hm.put("Anand", 20); 
  hm.put("Mary", 20); 
  hm.put("Ravi", 21); 
  hm.put("John",19); 
  System.out.println("Contents: "+hm); 
   
  System.out.println(); 
  Set<String> keys = hm.keySet(); 
  for(String k: keys) 
   System.out.println(k+" -- "+hm.get(k)); 
   
  System.out.println(); 
   
  Set<Map.Entry<String, Integer>> entries = hm.entrySet(); 
  for(Map.Entry<String,Integer> each: entries) 
   System.out.println(each.getKey()+" -- "+each.getValue()); 
   
  System.out.println(); 
 } 
}