kotlin 疑问

1、伴生对象的引用

答案：

coroutineContext[Job]

2、Kotlin 的尾递归

左子树遍历

internal class CombinedContext(
    private val left: CoroutineContext,
    private val element: Element
) : CoroutineContext, Serializable {
    override fun <E : Element> get(key: Key<E>): E? {
        var cur = this
        while (true) {
            cur.element[key]?.let { return it }
            val next = cur.left
            if (next is CombinedContext) {
                cur = next
            } else {
                return next[key]
            }
        }
    }

3、并发问题

如非必要不要随意切换线程

            GlobalScope.launch {
                var num = 0
                Executors.newFixedThreadPool(10).asCoroutineDispatcher().use { executorCoroutineDispatcher ->

                    List(1000000) {
                        GlobalScope.launch(executorCoroutineDispatcher) {
                            num++;
                        }
                    }.forEach {
                        it.join()
                    }

                }
                print(num)
            }
            Thread.sleep(1000)

> Task :Main.main()
999995

协程方法另一种写法

全局异常处理

String[] PermissionString={Manifest.permission.READ_EXTERNAL_STORAGE};
ActivityCompat.requestPermissions(SettingGuideActivity.this,
PermissionString, 1);