Kotlin协程中launch/join和async/await有什么区别 [英] What is the difference between launch/join and async/await in Kotlin coroutines

问题描述

在kotlinx.coroutines库中，您可以使用launch(带有join)或async(带有await)启动新协程.它们之间有什么区别?

In the kotlinx.coroutines library you can start new coroutine using either launch (with join) or async (with await). What is the difference between them?

推荐答案

• launch 用于射击并忘记协程.这就像启动一个新线程.如果launch中的代码以异常终止，则将其视为线程中的未捕获异常-通常在后端JVM应用程序中打印到stderr并使Android应用程序崩溃. join 用于等待启动的协程的完成，并且不会传播其异常.但是，崩溃的 child 协程也将其父级与相应的异常取消.

  • launch is used to fire and forget coroutine. It is like starting a new thread. If the code inside the launch terminates with exception, then it is treated like uncaught exception in a thread -- usually printed to stderr in backend JVM applications and crashes Android applications. join is used to wait for completion of the launched coroutine and it does not propagate its exception. However, a crashed child coroutine cancels its parent with the corresponding exception, too.

    async 用于启动协程以计算结果.结果由

    async is used to start a coroutine that computes some result. The result is represented by an instance of Deferred and you must use await on it. An uncaught exception inside the async code is stored inside the resulting Deferred and is not delivered anywhere else, it will get silently dropped unless processed. You MUST NOT forget about the coroutine you’ve started with async.

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