TreeMap usage - sort by key

package beginnersbook.com;
import java.util.HashMap;
import java.util.Map;
import java.util.TreeMap;
import java.util.Set;
import java.util.Iterator;

public class Details {

    public static void main(String[] args) {

         HashMap<Integer, String> hmap = new HashMap<Integer, String>();
         hmap.put(5, "A");
         hmap.put(11, "C");
         hmap.put(4, "Z");
         hmap.put(77, "Y");
         hmap.put(9, "P");
         hmap.put(66, "Q");
         hmap.put(0, "R");

         System.out.println("Before Sorting:");
         Set set = hmap.entrySet();
         Iterator iterator = set.iterator();
         while(iterator.hasNext()) {
               Map.Entry me = (Map.Entry)iterator.next();
               System.out.print(me.getKey() + ": ");
               System.out.println(me.getValue());
         }
         Map<Integer, String> map = new TreeMap<Integer, String>(hmap); 
         System.out.println("After Sorting:");
         Set set2 = map.entrySet();
         Iterator iterator2 = set2.iterator();
         while(iterator2.hasNext()) {
              Map.Entry me2 = (Map.Entry)iterator2.next();
              System.out.print(me2.getKey() + ": ");
              System.out.println(me2.getValue());
         }
    }
}

output 👍

Before Sorting:
0: R
4: Z
5: A
66: Q
9: P
77: Y
11: C
After Sorting:
0: R
4: Z
5: A
9: P
11: C
66: Q
77: Y