In this blog we are going to discuss Kotlin and RXKotlin, so let’s start the topic.

About Kotlin –

Kotlin is a language that combines functional programming and object-oriented programming in a distinctive, unrestricted, and self-sufficient platform. Kotlin is run on a Java virtual machine and it is an open-source programming language.

You can check my other blog regarding Flutter app development .

These are some key points of kotlin –

• Semicolon isn’t required in kotline programs.
• Kotlin doesn’t support static member
• Kotlin supports Lambda Expression
• In, Kotlin variables of a primitive type 
• Kotlin doesn’t require any variable data type 
• Kotlin programs don’t require semicolons 
• Kotlin has Language scripting capabilities 
• Kotlin doesn’t offer implicit conversions
• Kotlin allows users to create an extension
• Kotlin compilation are fast
• Kotlin has trimmed code
• Kotlin combines the oops and functional component

Kotlin History –

There are landmarks and key points of kotlin history.

• Kotlin was launched his version v1.0 in 2016
• Google announced his first-class support of Kotlin in Android In 2017
• Kotlin v1.3 version released in 2018 brings coroutines for asynchronous programming.
• Google announced Kotlin as its preferred programming language for Android application developers in 2019.

Kotlin Advantage –

Here are some lists of advantages of using kotlin.

• Kotlin uses the Multiplatform framework and extracts one common codebase.
• Kotlin has built-in null safety support.
• In kotlin there is less room for errors.
• Kotlin divides the large apps into smaller layers.
• It helps developers to create extension functions.
• Kotlin is very easy to read and write because it is a statically-typed language.
• Writing new code in kotlin takes very less time.

Kotlin Disadvantage –

Here are some lists of disadvantages of using kotlin.

• The Kotlin developer community is very small, that’s why learning material is less.
• Compilation speed is slower than java.
• Kotlin is a highly declarative language

About RxKotlin –

Rx stands for Reactive Extensions (Rx), but Rxkotlin is not an implementation of Reactive Extensions, it’s a collection of extension methods. RxKotlin uses the RxJava library with API design.

These are some important points about RxKotlin.

• As well RxKotlin is dependent on RxJava.
• RxKotlin does not depend upon RxAndroid.
• RxAndroid and RxKotlin use RxJava.
• RxKotlin is only a wrapper over the original RxJava.
• No need to use RxKotlin if you are using RxJava.
• You can use RxJava with Kotlin out-of-the-box.
• Rx Java, Rx Kotlin, or Rx Swift all are the implementation of Reactive Extensions in that particular language.

Setup The RxKotlin –

To set up the project first you need to add the RxKotlin dependencies in your project.

1. Add the following code in your pom.xml file

dependency>

    <groupId>io.reactivex.rxjava2</groupId>

    <artifactId>rxkotlin</artifactId>

    <version>2.3.0</version>

</dependency>

2. Add the following code in build.gradle

   implementation ‘io.reactivex.rxjava2:rxkotlin:2.3.0’

Observables Creation in RxKotlin – 

RxKotlin has a number of extension methods for creating Flowable objects and Observables from collections.

Every array type has a toFlowable() and toObservable() method, it is like the following code.

val observable = listOf(1, 1, 2, 3).toObservable()

observable.test().assertValues(1, 1, 2, 3)

val flowable = listOf(1, 1, 2, 3).toFlowable()

flowable.buffer(2).test().assertValues(listOf(1, 1), listOf(2, 3))

Map and Multimap in Observable and Flowable – 

• We have Pair instances for Observables or Flowable that produce a Single observable that produces a Map.

val list = listOf(Pair(“a”, 1), Pair(“b”, 2), Pair(“c”, 3), Pair(“a”, 4))

val observable = list.toObservable()

val map = observable.toMap()

assertEquals(mapOf(Pair(“a”, 4), Pair(“b”, 2), Pair(“c”, 3)), map.blockingGet())

• We use the values associated with a key into a collection for this we use the toMultimap.

val list = listOf(Pair(“a”, 1), Pair(“b”, 2), Pair(“c”, 3), Pair(“a”, 4))

val observable = list.toObservable()

val map = observable.toMultimap()

assertEquals(

  mapOf(Pair(“a”, listOf(1, 4)), Pair(“b”, listOf(2)), Pair(“c”, listOf(3))),

  map.blockingGet())

Combining Flowables and Observables –

Here we combine the observables with flatMap.

val subject = PublishSubject.create<Observable<String>>()

val observable = subject.mergeAll()

         Or 

val observable = subject.flatMap { it }

Different Types Values Handling – 

Here we check how you handle the different types of data handling in RxKotlin. It handles the following 2 types of values.

• cast values from one type to another, 
• filter the values that are not of a certain type

val observable = Observable.just<Number>(1, 1, 2, 3)

observable.cast<Int>().test().assertValues(1, 1, 2, 3)

In this article, we have thoroughly reviewed RxKotlin and Kotlin, i think you understand the concept well now