How to sort a HashMap if both have same key?

Question

I have a hashmap which have same value but different key.I want to sort them how this will possible?

Image of this Hashmap is below

HashMap Image

public static HashMap<String,Integer> entry = new HashMap<>();

Answer 1

Use TreeMap for sorting by key

Use below code for sorting by value:

private static HashMap sortByValues(HashMap map) { 
       List list = new LinkedList(map.entrySet());
       // Defined Custom Comparator here
       Collections.sort(list, new Comparator() {
            public int compare(Object o1, Object o2) {
               return ((Comparable) ((Map.Entry) (o1)).getValue())
                  .compareTo(((Map.Entry) (o2)).getValue());
            }
       });

       // Here I am copying the sorted list in HashMap
       // using LinkedHashMap to preserve the insertion order
       HashMap sortedHashMap = new LinkedHashMap();
       for (Iterator it = list.iterator(); it.hasNext();) {
              Map.Entry entry = (Map.Entry) it.next();
              sortedHashMap.put(entry.getKey(), entry.getValue());
       } 
       return sortedHashMap;
  }

Please check here for details.

Here some good example for sorting HashMap in Java by Keys and Values.

Answer 2

HashMap is not meant to keep entries in sorted order, but if you have to sort HashMap based upon keys or values, you can do that in Java. Sorting HashMap on keys is quite easy, all you need to do is to create a TreeMap by copying entries from HashMap. TreeMap is an implementation of SortedMap and keeps keys in their natural order or a custom order specified by Comparator provided while creating TreeMap. This means you can process entries of HashMap in a sorted order but you cannot pass a HashMap containing mappings in a specific order, this is just not possible because HashMap doesn't guarantee any ordering. On other hand, sorting HashMap by values is rather complex because there is no direct method to support that operation. You need to write code for that. In order to sort HashMap by values you can first create a Comparator, which can compare two entries based on values. Then get the Set of entries from Map, convert Set to List and use Collections.sort(List) method to sort your list of entries by values by passing your customized value comparator. This is similar of how you sort an ArrayList in Java. Half of the job is done by now. Now create a new LinkedHashMap and add sorted entries into that. Since LinkedHashMap guarantees insertion order of mappings, you will finally have a Map where contents are sorted by values.

Detailed information over here: https://www.java67.com/2015/01/how-to-sort-hashmap-in-java-based-on.html