Map values to list

Question

I have an Map<String,Integer> which is sorted by value like that

  public void sortList(Map<String,Integer> map){
         set = map.entrySet();
        list = new ArrayList<Map.Entry<String, Integer>>(set);
        Collections.sort( list, (o1, o2) -> (o2.getValue()).compareTo( o1.getValue() ));

    }

I need to copy all values to new list

  word_used = new ArrayList<Integer>(map.values());

but it saves in non-sorted order

Answer 1

When you sort that list you created from the entrySet , it doesn't change the order of the entries in the original Map . You'll have to return the list from your sortList method if you want a List of the sorted values.

map.values() will not return the values sorted, since the values are not kept in any specific order in the Map . Some Map implementations (such as TreeMap ) keep the keys sorted, but not the values.

Answer 2

First extract the list, sort it and then create a new list with it.

List<Integer> tmp = map.values();
Collections.sort(tmp);
word_used = new ArrayList<Integer>(tmp);

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java-8

word_used = new ArrayList<Integer>(map.values()
                                      .stream()
                                      .sorted()
                                      .collect(Collectors.toList()));