CODEWITHSUNDEEP
javacollectionsmapsguavamultimap
izengod
izengod

Reputation: 1156

Sort a TreeMultimap in descending (reversed) order

The output is: Top pincodes: {1=[456008, 456600, 456666], 2=[560089], 4=[456098, 567789]}

I want them to be in this order: {4=[456098,567789], 2=[560089], 1=[456008, 456600, 456666]}

HashMap<Integer, Integer> totalCustomersByPin = new HashMap<Integer, Integer>();
TreeMultimap<Integer, Integer> totalDeliveriesToPin = TreeMultimap.create();
Iterator<Entry<Integer, Integer>> iterator = totalCustomersByPin.entrySet().iterator();

while (iterator.hasNext()) {
    Entry<Integer, Integer> pair = iterator.next();
    totalDeliveriesToPin.put(pair.getValue(), pair.getKey());
}
System.out.println("Top pincodes:" + totalDeliveriesToPin);

Upvotes: 2

Views: 5171

Answers (2)

Marian Kl&#252;hspies
Marian Kl&#252;hspies

Reputation: 17637

This is what I´ve found what is actually working for me

  SortedSetMultimap<String, String> multiMap = TreeMultimap.create(
                Comparator.reverseOrder(), // Key sorting
                (o1, o2) -> 0              // Value sorting
        );

Upvotes: 0

Tunaki
Tunaki

Reputation: 137104

You can set a key comparator when creating the TreeMultimap. You can use Ordering.natural() and then call reverse() to sort the key in the reverse order of their natural ordering.

Sample code:

public static void main(String[] args) {
    TreeMultimap<Integer, Integer> map = TreeMultimap.create(Ordering.natural().reverse(), Ordering.natural());
    map.put(1, 456008);
    map.put(1, 456600);
    map.put(1, 456666);
    map.put(2, 560089);
    map.put(4, 456098);
    map.put(4, 567789);
    System.out.println(map);
}

This will print: {4=[456098, 567789], 2=[560089], 1=[456008, 456600, 456666]}.

Upvotes: 8

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