Kotlin hot flow. It’s part of Kotlin’s coroutines, which are used for writing code that doesn’t block the app while waiting for something to finish, like a network call or a file to load. What comes to mind when you hear the word “flow”? It may occur to you as something continuous, such as a stream. Flows and Mar 4, 2024 · Conclusion Kotlin Flow is a powerful tool in the arsenal of an Android developer, simplifying asynchronous data handling with robust, type-safe operations. What are Flows? A stream of data that can be computed asynchronously is referred to as a Flow . May 8, 2025 · As I continue my Kotlin journey, I explored one of the most important concepts in reactive programming with Kotlin: the difference between Cold Flow and Hot Flow. Sep 29, 2023 · Kotlin Flow is a powerful and expressive way to work with asynchronous and stream-like data in Kotlin. Hot Flows are those that start emitting values even if there are no collectors attached to them. Cancellation semantics Flow collectors are cancelled when the original channel is closed with an exception. One of the critical concepts when working with flows in Kotlin Coroutines is understanding the difference between cold and hot streams. Sep 8, 2024 · Flow is a powerful concept in Kotlin and is widely used in Android development for managing asynchronous data streams. Hot flows implement both CancellableFlow and FusibleFlow interfaces while Cold flows only implement former one. At the beginning it looked more simple. To update state and send it to the flow, assign a new value to the value property Mar 7, 2025 · Understanding Hot and Cold Flows in Kotlin Kotlin Flow is a powerful feature for handling reactive streams of data. The goal was simple with this one, to simplify asynchronous … Apr 18, 2025 · Apr 18, 2025 -- 1 Kotlin Flow — Deep Dive If you’re prepping for an Android or Kotlin interview and haven’t fully wrapped your head around Kotlin Flow, stop right here. This article will focus on another crucial concept in Kotlin Coroutines: Kotlin flows. As promised, this is a follow up to that on Flows. 📡 Learn everything about SharedFlow in Kotlin Coroutines! SharedFlow is a powerful hot flow that broadcasts values to multiple collectors simultaneously. Jan 6, 2025 · What is SharedFlow? SharedFlow is a part of the Kotlin Flow API and is a type of hot flow. There is no one-size-fits-all but one of the most common usages of Flow and StateFlow in Android apps today What is the difference between hot data sources (like list or channel) and cold ones (like sequence or flow)? Mar 4, 2025 · Hot Flow or Cold Flow? LiveData or Flow? StateFlow or SharedFlow? Let's dive in and find out when to use each in Kotlin and Android. When we merge flows, we combine data from different sources into a single stream, facilitating concurrent processing and enhancing performance. This article will explain the differences and provide practical examples of both types. 💻 Let me be your mentor and become an industry-ready Android developer in 10 weeks:h Dec 1, 2024 · In Kotlin, one of the most effective ways to approach reactive programming is by using the Kotlin Flow API. State Flow Problem The most Dec 5, 2023 · Kotlin Flows: Converting cold flow to hot and back (with examples and outputs) In the first part of this wonderful journey into the bushes of Kotlin Flows, I went through the basic topic. Learn hot vs. The starting of the sharing coroutine is controlled by the started parameter, as explained in the Oct 3, 2020 · In both cases Flow is behaving the same, what you missed is that Flow. I will cover the following topics in several parts: 1️⃣ What is Flow in Kotlin ? Hot and cold data sources Why do we need to learn it ? Start Using Flow Builders in Flows 2️⃣ Operators in Flows Exception Handling StateFlow and SharedFlow Creates a cold flow that produces values from the array. In this beginner’s guide, we’ll explore Kotlin Flow, understand its concepts, and see how it can simplify asynchronous programming in Kotlin. With Flow in Kotlin now we can handle a stream of data sequentially. Its current value can be retrieved via the value property. A shared flow is called hot because its active instance exists independently of the presence of collectors. But Flow is a cold observable, where every subscriber gets their own data (independent from other subscribers). Sep 29, 2024 · In Kotlin (and programming in general), hot flow and cold flow are terms used to describe the behavior of reactive streams or data flows, especially when working with coroutines and asynchronous See full list on kotlinlang. But I still get confused about when I should use Flow and when I should use Channel. Flow is essentially a reactive stream of data that can be emitted from a producer and Jun 3, 2023 · In recent years, Kotlin Flow has gained immense popularity in the Android development community as a powerful reactive streams library. Mar 10, 2025 · Learn everything about Kotlin Flows, from streams and operators to shared and state flows. This differentiation is essential for writing efficient and predictable asynchronous code. It represents a stream of values that are computed asynchronously and emitted Sep 27, 2022 · In this blog, we are going to learn what is Flow API in Kotlin. This means that emitted items will be different from the same running source on each collection. One element will be emitted to one collector only. Jul 30, 2021 · First of all, All of the flows including cold & hot flows implement Flow interface which you can find in the top of the digram. I’ve … A hot Flow that shares emitted values among all its collectors in a broadcast fashion, so that all collectors get all emitted values. This is not what a normal Flow/Livedata would do thus wasting potential resources keeping a series of components working while, for example, the UI is stopped. May 29, 2024 · Mastering in Kotlin — Part-6- Flow and use cases Kotlin Flow is a powerful asynchronous data stream processing library that brings reactive programming to Kotlin. Nov 20, 2024 · Hello Buddy’s, When working with Kotlin Coroutines and Flow, you may encounter the terms cold flow and hot flow. 4. Starting from kotlinx. 0 in its coroutines library. Dec 20, 2022 · This is how Hot Flow can store data. May 7, 2023 · Learn how to use Kotlin Coroutine Hot Flows to manage continuous data streams and build reactive applications. ” It’s a useful distinction between two ways of working with an asynchronous data stream. While Cold Flows are useful in many scenarios, there are situations where they fall short, especially in cases where data is generated continuously. May 7, 2023 · Difference Between Flows and Channels in Kotlin Flows are cold stream while channels are hot stream. coroutines package and is designed to handle a continuous stream of data that is known as flows. Feb 22, 2024 · Every flow “operator” function (the nonterminal ones) returns a new cold flow whose behavior under the hood is that each time they are collected, they begin collecting from their parent flow and then do something with those results to achieve whatever emission behavior they are supposed to do. It’s an implementation of the Reactive Stream specification, an initiative whose goal is to provide a standard for asynchronous that executes sequentially. Let's start learning about the StateFlow and SharedFlow in Kotlin. Mar 10, 2023 · In Kotlin, there are two types of flows: Cold Flow and Hot Flow. Flow collectors Kotlin Flows are widely used in the Kotlin / Android development, but are you sure to really know how it works? Let's look at 8 code samples to see if you understand it. Jun 23, 2024 · I’ve been looking more into Kotlin coroutines last week. Oct 13, 2021 · A Hot flow that will be collecting values so as long as the scope in which it was started is Started, and will stop when stopped. Dec 10, 2022 · In this blog, we will learn about Cold Flow vs Hot Flow in Kotlin. They represent different ways of emitting and consuming data Feb 3, 2025 · Kotlin’s Hot and Cold Flows Understanding the Difference If you’ve tried or read something about Kotlin’s Flow API, you probably came across the terms “hot” and “cold” flows. Dec 28, 2022 · There are a lot of excellent docs on StateFlow and SharedFlow out there and I won’t rehash it here. Nov 24, 2023 · Hey fellow Kotlin enthusiasts! Are you ready to dive into the world of Kotlin Flow and uncover the mysteries of Hot and Cold Flows? 🌊 If you've been wondering how Kotlin handles asynchronous Dec 3, 2023 · Kotlin Flows: Init, emit and collect (with examples and outputs) I’m easy (no) to learn new stuff, and it is the way easier for me to understand how some code works by looking at the output. Flows are a data structure you didn’t know, but you can’t live without them once you know them. A state flow is a hot flow because its active instance exists independently of the presence of collectors. Choosing the right type ensures better performance and correct behavior in Jul 13, 2023 · Hot vs cold flows — Kotlin Coroutines In Kotlin, a “hot flow” refers to a type of flow that produces values regardless of whether there are active collectors. State flow never completes. What Is Kotlin Flow? Kotlin Flow is a part of Kotlin Coroutines and offers a reactive streams API to handle data asynchronously. Unlike regular Flow, which is cold (i. Whether you’re managing UI state with StateFlow, broadcasting Kotlin’s Flow API is a powerful tool for building reactive, asynchronous data streams. Here’s an overview of both types of flows and their use cases: A SharedFlow is a hot flow that can Dec 9, 2024 · Conversely, hot streams start producing items immediately. See also consumeAsFlow which ensures that the resulting flow is collected just once. While “cold flows,” which Jan 30, 2025 · When working with Kotlin Flow, understanding the distinction between cold flows and hot flows is crucial for designing efficient and responsive applications. By understanding the basics of Flow, operators, and how to collect data, you can handle asynchronous streams more In this video you'll learn the differences between the typical observable classes we have in Android. Learn when to use each for efficient, scalable Android apps. In this article, we will explore features of shared and state flows with unit testing. These concepts define how data streams behave when being observed by collectors Aug 9, 2023 · Discover Kotlin’s Cold Flow & Hot Flow: Unveil the power of reactive programming. These two types of flows dictate how The Flow interface does not carry information whether a flow is a cold stream that can be collected repeatedly and triggers execution of the same code every time it is collected, or if it is a hot stream that emits different values from the same running source on each collection. Cold Flows: The Default Sep 10, 2025 · Master Kotlin's Flow API by understanding the critical differences between Cold and Hot Flows. In the case of the cold flow it clearly ends after the 5 values are emitted so it finishes execution. It is part of the Kotlin Coroutines library and provides a seamless way to handle data streams, making it easier to work with asynchronous operations. 3 that provides a reactive-streams-like API for building and processing streams of data. The current state value can also be read through its value property. Feb 11, 2021 · What are the differences between SharedFlow and StateFlow? And how to use these in MVI architecture? is it better to use simple Flow or these as states and events?. A Flow basically emits data asynchronously in the form of … Oct 29, 2021 · But now in Kotlin Jetbrains came up with Flow API. Tagged with kotlin, android. If the unit or module exposes a flow, you can read and verify one or multiple items emitted by a flow in the test. 1. Flow, like LiveData and RxJava streams, allows you to But Flow main goal is to have as simple design as possible, be Kotlin and suspension friendly and respect structured concurrency. org Feb 26, 2024 · StateFlow and SharedFlow are Flow APIs that enable flows to optimally emit state updates and emit values to multiple consumers. In this video you'll learn about hot and cold streams with Kotlin Flows. May 4, 2023 · Introduction to Kotlin Flow Explore the various facets of Kotlin Flow. The article also discusses practical examples and scenarios for using each type of flow Mar 23, 2023 · Dive into the world of Kotlin flows with this in-depth comparison of SharedFlow and StateFlow. Achieving this goal would be impossible without reactive pioneers and their tremendous work. Refer to Cold Flow vs Hot Flow. Dec 1, 2024 · Kotlin Coroutines provide a way to handle asynchronous programming effectively by using coroutines and flows. Sometimes we’ll work at once with many flows that we need to merge to process data efficiently. Dec 2, 2024 · In Kotlin, a hot flow is a type of flow that continuously emits values, even when there are no active collectors, such as with a SharedFlow or StateFlow. A call to Flow. One of the most popular features of coroutines is the Flow API, which allows for asynchronous data streams to be processed in a more efficient and streamlined manner. collect on a state flow never completes normally, and Sep 22, 2024 · Kotlin Coroutines offer a powerful API with Flow, which can be divided into Cold Flows and Hot Flows. ⭐ Get certificates for your future job⭐ Save countless h Apr 3, 2023 · Kotlin logo As Android projects migrate to Kotlin, many developers are turning to Kotlin’s coroutines library for asynchronous programming. Sep 24, 2025 · When building Android apps using Kotlin Flow, it’s essential to know the difference between Cold Flows and Hot Flows. #Flow #kotlin #StateFlow #SharedFlow #LiveData #jetpackcompose This episode we will discussing about the basics of the flow and difference between flow, stateflow, sharedFlow and LiveData in Feb 11, 2023 · この記事は Kotlin CoroutinesのFlowが何かよくわからないので基本を知りたい人向け この記事1つでFlowの基本を網羅できればという強い気持ちによって少々長くなってしまったので流し読みでも 私自身も勉強中で、この記事は百戦錬磨の実践から学んだ Dec 26, 2020 · So they introduced Flow. It emits value only when someone collects or subscribes to it. Kotlin Coroutines introduced a powerful API for asynchronous programming, and with it, the concept of Flows, which can be categorized as hot or cold. By the end of the chapter, you should have a good understanding of the Flow, StateFlow, and SharedFlow Kotlin types, and appreciate the difference between hot and cold flow streams. 3. According … May 10, 2023 · By understanding the differences between cold and hot streams in Kotlin Flow, you’ll be better equipped to make informed decisions about how to handle streams in your projects. This API is part of Kotlin's kotlinx. You could do the same with ConflatedBroadcastChannel. That means flow will send a sequence of data asynchronously and associated collectors will receive the data. Aug 15, 2024 · Cold Flow and Hot Flow are two fundamental concepts in Kotlin Coroutines that have significant implications in Android development. Flow is a stream processing API in Kotlin developed by JetBrains. By embracing Flow and its principles, developers can write more concise, maintainable, and testable code, ultimately leading to better app performance and user experience. Note: The Testing Dec 30, 2022 · Part 2 - Introduction to Kotlin Flows and Channels Part 3 - Exploring Different Ways to Collect Kotlin Flow Part 4 - Convert Flow to SharedFlow and StateFlow Part 5 - Flow, SharedFlow, StateFlow Class Diagram Part 6 - Kotlin Flow - Combine, Merge and Zip Flow is a cold stream. Sep 30, 2024 · Don’t Let It Leak: Best Practices for Stopping Flow Collect in ViewModels Kotlin Flow provides a powerful, efficient, and declarative way to manage asynchronous data flows. Let’s now explore flow in detail. In this chapter, we will introduce Kotlin Flows and explore how these can be used to return sequential streams of results from coroutine-based tasks. coroutines. Instead, I will just provide a few ideas how to choose the right hot flow as well as a couple of examples of using them in a lifecycle-aware manner, unit testing them in ViewModels. But there is a difference between cold flow and hot flow. Oct 28, 2022 · Part 2 - Introduction to Kotlin Flows and Channels Part 3 - Exploring Different Ways to Collect Kotlin Flow Part 4 - Convert Flow to SharedFlow and StateFlow Part 5 - Flow, SharedFlow, StateFlow Class Diagram Part 6 - Kotlin Flow - Combine, Merge and Zip Kotlin Flow is a cold stream, Kotlin Channel is a hot stream. One of the fundamental concepts to understand when working with flows is the distinction between hot and cold flows. The flow being cold means that the array components are read every time a terminal operator is applied to the resulting flow. The previous article focused on some of the fundamentals of coroutines such as CoroutineContext, CoroutineScope, Coroutine Builder etc. What is … Mar 1, 2024 · A comprehensive guide to understand Kotlin Flows Kotlin introduced Flow API a while back in version 1. Whereas, shared flows allow you to replay and buffer emissions. It allows for handling continuous sequences of values Represents the given receive channel as a hot flow and receives from the channel in fan-out fashion every time this flow is collected. Sep 16, 2024 · Kotlin Flow is a powerful tool that simplifies reactive programming in Android. So the upstream flow can be hot or cold, but the returned downstream flow is always cold. Converts a cold Flow into a hot StateFlow that is started in the given coroutine scope, sharing the most recently emitted value from a single running instance of the upstream flow with multiple downstream subscribers. Jul 23, 2025 · Kotlin Flow is a tool that helps developers work with data that changes over time like search results, live updates, or user input. It covers the differences between cold flows, which only emit values when there is an active collector, and hot flows, which emit values regardless of collectors. Its integration with … Apr 5, 2024 · Today I will try to discuss the salient dissmilarities between Hot and Cold flow in Kotlin. Jun 21, 2023 · What are Kotlin flows in Android development First of all, what are flows in Android development? When talking about flows we can think of them as streams of data whose values are being computed asynchronously. e. 0 Kotlin provides an updated Flow API that includes two subtypes StateFlow and SharedFlow that represent hot streams. Dec 26, 2022 · In this series of article, I am going to show you how Flow works in Kotlin and how we can start using it in our Android projects. It’s built on top of coroutines, offering a more reactive and efficient way Dec 19, 2019 · I'm recently studying and reading a lot about Flow and Kotlin Coroutines. Meanwhile in the hot flow the completion of the flow depends on code that executes AFTER collect would return, a classic deadlock. May 28, 2023 · In the first part of this series (🔗 read here), we took a deep dive into Kotlin Coroutine Flows and explored the concept of Cold Flows. State Flows have features such as sharing strategies and conflation. Understanding the distinction between these Dec 12, 2022 · Unit Testing ViewModel with Kotlin Flow and StateFlow Before jumping into the StateFlow and SharedFlow, we should have an understanding of the Cold Flow and Hot Flow. See the StateFlow documentation for the general concepts of state flows. Using Flow in Kotlin provides a coroutine-based, type-safe way of handling such streams. Sep 12, 2024 · 本文介绍了Kotlin中`Flow`的概念及其类型，包括冷流（Cold Flow）、热流`SharedFlow`及具有最新值的`StateFlow`。文中详细描述了每种类型的特性与使用场景，并提供了停止`Flow`的方法，如取消协程、使用操作符过滤及异常处理。通过示例代码展示了如何运用这些概念。 May 7, 2024 · Kotlin Flow, StateFlow and SharedFlow Android Kotlin flow provides an efficient way to handle asynchronous data in the form of streams. Kotlin provides many features out of the box that we can use to perform various tasks in our project. hot and cold flows Both hot and cold flows … Nov 1, 2023 · A Comprehensive Guide to Understanding Hot and Cold Flows in Android App Development In the realm of Android app development, efficiently managing data streams and asynchronous operations is a … Sep 7, 2024 · Playing with Cold Flow and Hot Flow Flow is used to stream data asynchronously. It’s important to note that there are 2 types of flows: hot flows and cold flows. Feb 4, 2023 · 👉🏻After reading this article, you can check this guide: Kotlin Flows Testing Full Guide Kotlin Flows is a new feature in Kotlin 1. By definition, cold flows don’t produce any values until a terminal operator is used on them Oct 13, 2024 · Kotlin Flow is a powerful, coroutine-based stream API designed for managing asynchronous data streams in a structured and reactive manner. cold flows, StateFlow, coroutines, and how to write clean, modern async code. With SharedFlow you get a hot observable that emits independently of having any subscriber (s). Jun 5, 2021 · Learning State & Shared Flows with Unit Tests 10 minute read State and shared Flows are hot streams that can propagate items to multiple consumers. It serves as a Kotlin friendly alternative of Live Data, for managing an observing state in android applications. On the other hand, a cold flow only starts Jun 5, 2025 · Kotlin flow 全面解析：从基础到高级 11 分钟阅读时长 发布时间： June 05, 2025 一个典型的 flow 包含哪些部分？ 这是一个非常简单的问题，但是也最为我们所忽略。我们来看一个典型的 flow： Dec 9, 2024 · In Kotlin coroutines, the Flow is a powerful construct for handling sequential data streams asynchronously. Improve your Android app's performance with this in-depth guide! Aug 28, 2024 · This article explains the concepts of hot and cold flows in Kotlin, detailing their characteristics, use cases, and how to convert between them. If the subject under test observes a flow, you can generate flows within fake dependencies that you can control from tests. It provides a seamless way to handle asynchronous and Dec 29, 2023 · In Kotlin, Flow builders are used to create instances of Flow which is a type that represents a cold asynchronous data stream that sequentially emits values and completes normally or with an Nov 19, 2024 · The way you test units or modules that communicate with flow depends on whether the subject under test uses the flow as input or output. Mar 29, 2025 · Hot and Cold — kotlin flow streams In the last article we understood the need for streaming data using flow in Kotlin. It allows developers to handle … Sep 16, 2025 · Don’t be mistaken about cold and hot flows may look similar, but they behave very differently in Kotlin Apr 10, 2024 · Introduction In the article Kotlin 101: Coroutines Quickly Explained, we saw how to use Kotlin Coroutines to write asynchronous code in a more natural and readable way. This single line definition is not enough to know about them. In such cases, Hot Flows are a powerful alternative that can help you manage and react to data streams in Jul 15, 2025 · A guide to understanding Kotlin Flows. collect suspends until the flow completes. Pe Jun 2, 2024 · Unlock the full potential of Kotlin programming with our comprehensive guide to Kotlin Flows! In this video, we dive deep into the differences between SharedFlow and StateFlow, demystify the Dec 21, 2024 · The Basics of Flow in Kotlin Flow is a part of Kotlin’s Coroutines library, designed for asynchronous data streams. Mar 14, 2024 · The collectors of a hot flow are called subscribers — the slight change in language is to emphasise the fact that the flow continues independently of the subscriber. So, now we have the idea about Cold Flow and Hot Flow. According to the official documentation of Flow, Flow is an asynchronous data stream that sequentially emits values and completes normally or with an exception. Both the StateFlow and SharedFlow are Hot Flows. If you execute the collect asynchronously in a Jul 12, 2024 · Kotlin flows on Android Stay organized with collections Save and categorize content based on your preferences. Dec 10, 2024 · State flow in Kotlin is a Hot Flow provided by Kotlin Coroutines Library, designed to hold and mange a state in a reactive programming model. Choose the best for your projects! Aug 15, 2023 · Maybe you’ve heard Kotlin programmers say that “channels are hot, flows are cold. StateFlow StateFlow is a state-holder observable flow that emits the current and new state updates to its collectors. So, without further ado, let’s dive Dec 3, 2024 · This article is your ultimate guide to mastering Kotlin Flow and understanding why it is considered the future of asynchronous programming. If you're working with Jetpack Compose, understanding the difference between hot and cold flows is critical Sep 17, 2024 · Flow is used to stream data asynchronously. Going from the basics, flow is something we use profoundly to handle asynchronous data streams without A SharedFlow that represents a read-only state with a single updatable data value that emits updates to the value to its collectors. A flow is a sequence of values that can be processed asynchronously and/or concurrently, and it can be created using different methods. This was all about the Cold Flow vs Hot Flow in Kotlin. , it starts emitting items only when collected), a SharedFlow Dec 21, 2022 · In this blog, we will learn about Cold Flow vs Hot Flow in Kotlin. muwvxtldysn3fyytdfu3x74vlsywd4v4axx6to8pbsvs1ovlm417u