Best way of grouping and sorting in kotlin-CodePudding

Hey I have huge data coming from server. I want to sort them and group them. I tried some code it's working fine. I just want to know is there any better way to optimise the code, which helps in better efficiency.

val products = ABC()
products?.sortedBy { it.category }?.groupBy { it.category }

Abc

data class Abc(
    val category: String? = null,
    val categoryId: String? = null,
    ...// more property
)

Can you guys know any better approach. Thanks

CodePudding user response：

By taking advantage of the fact that you are trying to sort the grouping keys, you can group by and sort at the same time by using a sorted map such as TreeMap.

Specify the map that you want groupBy to use by using groupByTo.

val map = products.groupByTo(TreeMap()) { it.category }

As groupByTo creates groups and puts the categories into the map, the keys will automatically be used to build a Red Black Tree (which is what a TreeMap is under the hood). Traversing map.keys will get you the keys in sorted order.