CODEWITHSUNDEEP
androidkotlinhashmap
JerryLi
JerryLi

Reputation: 99

Count number of elements in a Map<String, Map<String, Int>>? by its keys

I have Map<String, Map<String, Int>>.

How should I analyze it? I want to count how many values there are for each key.

Let's say we have a map like: {jack={a=1, b=2, c=3}, amy={d=1, a=3, c=1, e=5}

My aim is to getting the number of elements by each key of the map, something like: [jack=3, amy=4]

Upvotes: 1

Views: 2653

Answers (2)

Nicola Gallazzi
Nicola Gallazzi

Reputation: 8705

In Kotlin you only need to init your list as a Hashmap, then you can easily iterate on the hashMap and get keys and elements count:

val hashMap = hashMapOf(
            "jack" to mapOf("a" to 1, "b" to 2, "c" to 3),
            "amy" to mapOf("d" to 1, "a" to 3, "c" to 1, "e" to 5)
        )

        for (e in hashMap) {
            println("Key: ${e.key}, elementsCount: ${e.value.size}, elements: ${e.value}")
        }

Upvotes: 0

SpiritCrusher
SpiritCrusher

Reputation: 21043

You can iterate over Map and get the Entry for each key .

for (Map.Entry<String, Map<String, Integer>> entry : map.entrySet()) {
        System.out.println(entry.getKey() + " = " + entry.getValue().size());
    }

Kotlin equivalent will be 

for ((key, value) in map) {
        println(key + " = " + value.size)
    }

If you are only interested in size then this will do . You can further use entry.getValue() to iterate over inner map in case you need further data.

Upvotes: 1

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