How do you sort alphanumeric key of a map OR Sort map by key in java?

Problem statement:
How do you sort alphanumeric key of a map ?
Method-I:

1. import java.util.HashMap;
2. import java.util.Map;
3. import java.util.Set;
4. import java.util.TreeMap;
5. public class SortAlphanumericKeyInMap {
6.     public static void main(String[] args) {
7.         Map<String, String> map = new HashMap<>();
8.         map.put("question1", "1");
9.         map.put("question9", "2");
10.         map.put("question4", "2");
11.         map.put("question6", "7");
12.         // using TreeMap
13.         Map<String, String> treeMap = new TreeMap<>(map);
14.         Set<String> keys = treeMap.keySet();
15.         for (String key : keys) {
16.             System.out.println(key);
17.         }
18.     }
19. }

Output:

question1

question4

question6

question9

Method-II:

import java.util.*;

public class SortAlphanumericKeyInMap {

    public static void main(String[] args) {

        Map<String, String> map = new HashMap<>();

        map.put("question1", "1");

        map.put("question9", "2");

        map.put("question4", "2");

        map.put("question6", "7");

        Set<String> set = map.keySet();
        // This will iterate across the map in natural order of the keys.

        SortedSet<String> keys = new TreeSet<>(set);

        for (String key : keys) {

            System.out.println("sorted key: " + key + " | values: " + map.get(key));

        }

    }

}

Output:

sorted key: question1 | values: 1

sorted key: question4 | values: 2

sorted key: question6 | values: 7

sorted key: question9 | values: 2

Method-III:

import java.util.ArrayList;

import java.util.HashMap;

import java.util.Map;

import java.util.Set;

import java.util.List;

import java.util.Collections;

public class SortAlphanumericKeyInMap {

    public static void main(String[] args) {

        Map<String, String> map = new HashMap<>();

        map.put("question1", "1");

        map.put("question9", "2");

        map.put("question4", "2");

        map.put("question6", "7");

        Set set = map.keySet();

        // using List

        List keys = new ArrayList(set);

        Collections.sort(keys);

        for (Object key : keys) {

            System.out.println(key);

        }

    }

}

Output:

question1

question4

question6

question9