Search code examples
listsortingkotlinhashmaptreemap

How can i sort HashMap<String,Int> order by their values in Kotlin?

Here is my example, how can i do that in Kotlin?

var hashMapForTry = HashMap<String,Int>()

hashMapForTry.put("Hi",5)
hashMapForTry.put("What",7)
hashMapForTry.put("How",2)
hashMapForTry.put("Go",1)
hashMapForTry.put("Ford",9)
Solution

  • You cannot sort a HashMap because it doesn't guarantee that its entries will be iterated in any particular order. You can, however, arrange the items into a LinkedHashMap which keeps the insertion order:

        val resultMap = hashMapForTry.entries.sortedBy { it.value }.associate { it.toPair() }

    println(resultMap)

    Here the entries of hashMapForTry are sorted by entry value, then associate function converts the list of entries into a map that preserves the order of entries from that list.

    The result type of this function is Map<String, Int>. If you need to mutate the result further, you can use associateTo function and specify an empty destination LinkedHashMap as a parameter:

    ....associateTo(LinkedHashMap()) { ... }