kotlin flow mapNotNull

Kotlin 中的 Flow 是一种异步流式处理数据的方式。mapNotNull 是 Flow 类型的一个操作符，它接收一个 lambda 表达式作为参数，该 lambda 表达式将原始数据转换为新数据并筛选掉空值，最终返回一个新的 Flow。这个操作符适用于那些需要将原始数据映射为新数据并且希望在过滤掉 null 值后得到数据的场景。

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kotlin flow

Kotlin Flow is a reactive stream processing library in Kotlin that provides a declarative and asynchronous way of processing data streams. It is built on top of Kotlin Coroutines and allows developers to write asynchronous code in a sequential and concise manner, without the need for callbacks or complex threading models.

The key features of Kotlin Flow include:

1. Asynchronous processing: Kotlin Flow provides a way to asynchronously process data streams, allowing developers to write non-blocking, responsive applications.

2. Declarative programming model: Kotlin Flow uses a declarative programming model, which makes it easy to write code that is easy to read, understand, and maintain.

3. Composable operators: Kotlin Flow provides a set of composable operators that can be used to transform, filter, and combine data streams.

4. Backpressure support: Kotlin Flow provides support for backpressure, which allows data producers to slow down or stop producing data when the consumer is unable to keep up.

5. Integration with Kotlin Coroutines: Kotlin Flow is built on top of Kotlin Coroutines, which means that it can be easily integrated with other coroutine-based libraries and frameworks.

Overall, Kotlin Flow makes it easy to write efficient, asynchronous, and responsive applications that can handle data streams in a declarative and composable manner.

kotlin flow combine

Latest 和 merge 的区别是什么？

Kotlin Flow 中的 combineLatest 和 merge 都是将多个 Flow 合并为一个的操作符，但是它们有着不同的行为和用途。

combineLatest 操作符会在多个 Flow 中的任何一个 Flow 推送新值时重新合并所有 Flow 的最新值，并将每个 Flow 的最新值作为参数传递到合并后的 Flow 中的函数。这意味着 combineLatest 可以用于将多个 Flow 的最新值组合为一组数据，以更新 UI 或触发其他操作。

相反，merge 操作符将多个 Flow 中的所有值合并到单个 Flow 中，而不会等待所有 Flow 都推送新值。这意味着 merge 可以用于将多个 Flow 组合成单个 Flow，以供进一步处理或分析。

因此，两个操作符的主要区别在于它们如何合并 Flow 中的值以及它们适用的使用场景。