Sort Map using comparator

package test;

import java.util.*;

public class SortMap_TreeMap
{
public static void main(String[] args)
{
Map <String,String> unsortedmap = new HashMap<>();
unsortedmap.put("one", "one");
unsortedmap.put("tree", "tree");
unsortedmap.put("mount", "mount");
unsortedmap.put("bird", "bird");
unsortedmap.put("house", "house");
System.out.println("***************Unsorted Map**************");
printmap(unsortedmap);
System.out.println("************After sorting Map*************");
        Map<String, String> sortedMap = sortMap(unsortedmap);
        printmap(sortedMap);


}

private static Map<String, String> sortMap(Map<String, String> unsortedmap)
{
// copy unsortedmap to TreeMap
TreeMap <String,String> tm = new TreeMap<>(new SortMapComparator());
for(Map.Entry<String,String> entry : unsortedmap.entrySet())
{
tm.put(entry.getKey(), entry.getValue());
}
return tm;
}

private static void printmap(Map<String, String> unsortedmap)
{
  for(Map.Entry<String,String> entry  : unsortedmap.entrySet())
  {
  System.out.println(entry.getKey()+" : "+entry.getValue());
  }

}

}

=========================================

package test;

import java.util.Comparator;

public class SortMapComparator implements Comparator <String>

{

@Override

public int compare(String s1 , String s2) 

{

    return s1.compareTo(s2);

}

}