Compose has one rule: Composable functions should be pure. They take state in and produce UI out. No database calls. No API requests. No timers. No logging. But real apps need those things. You need to start a timer when a screen opens. You need to load data when an ID changes. You need to clean up a listener when a screen closes. That is what side effects are for. They let you safely run “impure” code inside Compose. ...
In the previous tutorial, you learned about advanced coroutine topics. Now let’s learn about Flow. Flow is Kotlin’s way of working with reactive streams. It lets you emit multiple values over time, with full support for coroutines. In this tutorial, you will learn: What is Flow Flow builder and emit/collect Operators: map, filter, take, transform Terminal operators: toList, first, reduce, fold flowOn for changing dispatchers combine and zip Error handling with catch and retry onCompletion and onEach conflate and distinctUntilChanged flatMapConcat, flatMapMerge, flatMapLatest StateFlow and SharedFlow (hot flows) stateIn and shareIn Practical examples What is Flow? Flow is a cold, asynchronous stream that emits values one at a time. ...
In the previous tutorial, you learned the basics of coroutines: suspend functions, launch, async, and structured concurrency. Now let’s dive deeper into error handling, supervisor jobs, and channels. In this tutorial, you will learn: CoroutineExceptionHandler SupervisorJob and supervisorScope Channels (send, receive, close) Channel types (buffered, conflated, unlimited) produce and consumeEach Fan-out and fan-in patterns select expression Mutex for shared mutable state withTimeout and withTimeoutOrNull Practical patterns Error Handling in Coroutines Error handling in coroutines is different from regular code. When a coroutine throws an exception, the behavior depends on whether you use launch or async. ...
In the previous tutorial, you learned about sequences. Now let’s learn about coroutines. Coroutines are Kotlin’s way of writing asynchronous code. They let you write code that looks synchronous but runs without blocking threads. In this tutorial, you will learn: Suspend functions launch — fire and forget async/await — get a result Dispatchers coroutineScope Structured concurrency Jobs and cancellation Timeouts Practical examples What Are Coroutines? A coroutine is a lightweight thread. You can run thousands of coroutines on a single thread. Unlike threads, coroutines are cheap to create and do not block the operating system thread they run on. ...