Software And Architecture

Introduction Sequences in Kotlin are similar to that of the stream s in Java, where in the evaluation happens lazily and the volume of data processed in each step in the chain are reducing based on the met criteria. Sample Let us consider the below given sample data class data class Car ( val model : String , val year : Int ) We can create a collection of cars so that we can evaluate both and understand the difference between collections and sequence   in Kotlin var cars = listOf ( Car ( "Toyota" , 2021), Car ( model = "Tesla-S" , 2022), Car ( "Mercedes - Maybach" , 2022) ) Sequence In the below given snippet of code, we are performing the filtering of cars by name and then printing the year println ( cars . asSequence (). filter { it . model == "Toyota" } . map { it . year } This produces the output as given below kotlin.sequences.TransformingSequence@b97c004a This is because the sequence is lazy and is not evaluated as there is

Collections This post provides some of the operations that can be done in the collections using kotlin The below is the base type definitions that will be used in the below collection queries data class Shop ( val name : String , val customers : List < Customer >) data class Customer ( val name : String , val city : City , val orders : List < Order >) { override fun toString () = " $ name from ${ city . name } " } data class Order ( val products : List < Product >, val isDelivered : Boolean ) data class Product ( val name : String , val price : Double ) { override fun toString () = "' $ name ' for $ price " } data class City ( val name : String ) { override fun toString () = name } Operations on collections // Return a list of customers, sorted in the descending by number of orders they have made fun Shop. getCustomersSortedByOrders (): List<Customer> = this .customers.sortedByDescending( { it -> it.order