为什么当启动时没有延迟（在Android中），它没有完成任务？

我在下面有一个简单的协程实验

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        runBlocking {
            launch {
                repeat(5) {
                    Log.d("Track", "First, current thread: ${Thread.currentThread()}'")
                    delay(1)
                }
            }

            launch {
                repeat(5) {
                    Log.d("Track", "Second, current thread: ${Thread.currentThread()}'")
                    delay(1)
                }
            }
        }
    }

这将打印所有 5 次，或者同时打印launch.

Track: First, current thread: Thread[main @coroutine#2,5,main]'
Track: Second, current thread: Thread[main @coroutine#3,5,main]'
Track: First, current thread: Thread[main @coroutine#2,5,main]'
Track: Second, current thread: Thread[main @coroutine#3,5,main]'
Track: First, current thread: Thread[main @coroutine#2,5,main]'
Track: Second, current thread: Thread[main @coroutine#3,5,main]'
Track: First, current thread: Thread[main @coroutine#2,5,main]'
Track: Second, current thread: Thread[main @coroutine#3,5,main]'
Track: First, current thread: Thread[main @coroutine#2,5,main]'
Track: Second, current thread: Thread[main @coroutine#3,5,main]'

但是，如果我delay(1)从两者的代码中删除launch

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        runBlocking {
            launch {
                repeat(5) {
                    Log.d("Track", "First, current thread: ${Thread.currentThread()}'")
                    // delay(1)
                }
            }

            launch {
                repeat(5) {
                    Log.d("Track", "Second, current thread: ${Thread.currentThread()}'")
                    // delay(1)
                }
            }
        }
    }

它只打印 2 次并按顺序打印launch。

Track: First, current thread: Thread[main @coroutine#2,5,main]'
Track: First, current thread: Thread[main @coroutine#2,5,main]'
Track: Second, current thread: Thread[main @coroutine#3,5,main]'
Track: Second, current thread: Thread[main @coroutine#3,5,main]'

为什么它没有完成所有 5 次循环？

注释在单元测试中运行它时工作正常（非 Android 环境，即所有 5 次都被打印）

回答

    repeat(10) {
        Log.d("all the same", "Hello World")
    }
    repeat(10) {
        Log.d("with indices", "Hello World $it")
    }