Sort a hashMap using 'values' automatically in a stream of inputs in Java [duplicate]

Question

Update the HashMap according to the values in a stream of inputs in descending order.

HashMap<String, Integer> map = new HashMap<String, Integer>();
map.put("a", 1);
map.put("b", 2);
map.put("c", 3);

When I print it in descending order, it will give output as :

{c=3, b=2, a=1}

And When I add this

map.put("a", map.get("a") + 10);

it should print as :

{a=11, c=3, b=2}

Get the EntrySet, add it to a List, sort that List however you want, print that List (and format it to look like a Map).# — BeUndead
– BeUndead, Commented Dec 1, 2020 at 15:12
HashMap has no order in Java. There is a same question: link — imraklr
– imraklr, Commented Dec 1, 2020 at 15:14

Bohemian · Accepted Answer · 2020-12-01 15:09:30Z

0

HashMaps have no order. NavigableMaps have order, but only based on the key. LinkedHashMaps iterate (and thus print) in insertion order.

Having a map’s toString() do what you want is not available in the JDK.

However, you could print via code what you want by streaming the entries, sorting by the negative of the value, then joining a string version of the entries together.

Such code could be within an overridden toString() method if you extended HashMap.

answered Dec 1, 2020 at 15:09

Bohemian♦

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