Styjun

I am practicing the use of hashmap and I would like to order my hashmap lexicographically. At this time, I have managed to do it with a list. This is the code of the list:

public class UsoUserlistaordenada 
 public static void inLista(ArrayList<User> l, User u ) throws Exception 
 // System.out.println(u.getName() +"/"+u.getShell());
 for(User u1 : l)
 int r = u1.getName().compareTo(u.getName());
 if(r==0) 
 return;
 
 if(r>0) 
 l.add(l.indexOf(u1),u);
 return;
 
 
// System.out.println(u.getName() +"/"+u.getShell());
 l.add(u);
 return;
 
 public static void main(String[] args) throws Exception 
 String line = null;
 ArrayList<User> lista = new ArrayList<User>();
 try (BufferedReader br = new BufferedReader(new FileReader("file"))) 
 while ((line = br.readLine()) != null) 
 String[] parts = line.split(":");
 String nombre_us = parts[0];
 String id_grupo = parts[3];
 String shell = parts[6];
 User u = new User(nombre_us,id_grupo,shell);
 inLista(lista,u);
 //System.out.println(u.getName() +"/"+u.getShell());
 
 int index=0;
 for(User s : lista)
 System.out.println(String.valueOf(index++)+": "+s);
 
 
 catch (Exception ex)
 
 ex.printStackTrace();
 
 

I would like to do it but with a hashmap. In this case, I would like to make the one with the least value have the key 0 and so on. Can you help me?

See HashMap vs TreeMap

HashMap doesn’t provide any guarantee over the way the elements are
arranged in the Map

Also i don't think that TreeMap is good solution for you. The sorting will be done by keys, not by values:

public static void main(String args[])

 String[] input = "a", "b", "f", "h", "e", "aa";

 int i = 0;
 Map<Integer, String> map = new TreeMap<>();
 for(String s: input) 
 map.put(i++, s);
 

 System.out.println(map);

If the key is integer, why not use simple array or list?

public static void main(String args[])

 String[] input = "a", "b", "f", "h", "e", "aa";

 List<String> list = new ArrayList<>(Arrays.asList(input));
 list.sort(Comparator.naturalOrder());
 System.out.println(list);

If you need sorting at the insertion time you could use TreeSet. It'll give you sorting and can be easily converted to array or list:

public static void main(String args[])

 String[] input = "a", "b", "f", "h", "e", "aa";

 Set<String> set = new TreeSet<>();
 set.addAll(Arrays.asList(input));

 System.out.println(set);

 String[] array = set.toArray(new String[0]);
 System.out.println(array[0]);

 List<String> list = new ArrayList<>(set);
 System.out.println(list.get(0));

The rest is comparator for sorting. You could use Comparator.comparing(User::getName) or implement the comparable interface.