如何在initState中等待异步 [英] How to wait for async in initState

问题描述

我有一个需要在有状态窗口小部件的initState中调用的异步函数，但是我不能使用await，因为initState不是异步的.

I have an async function that needs to be called in initState in an Stateful widget, but I cannot use await as initState is not async.

sendHealthData 是 async ，因为它从Health Api获取了一些信息，然后我需要将该信息发送到HomeSubScreen，后者是另一个 StatefulWidget .但是在创建HomeSubScreen时， sendHealthData 方法无法获取所有信息，因此，如果我尝试将参数值发送给 HomeSubScreen ，则值将为空.

sendHealthData is async as it get some information from the Health Api, and then I need to send that information to HomeSubScreen which is another StatefulWidget. But at the time the HomeSubScreen is created, the sendHealthData method didn't get all the information, so If I try to send some value in a param to the HomeSubScreen, the value will be null.

我该怎么做?

@override
  void initState() {
    super.initState();
    sendHealthData();
    _widgetOptions = <Widget>[
      HomeSubScreen(healthData),
    ];

  }

更新:如果添加了then()，则会出现以下错误:

Update: If I added a then() I get the following error:

NoSuchMethodError: The method 'elementAt' was called on null.

代码已更新:

@override
      void initState() {
        super.initState();
        sendHealthData().then((response){
             _widgetOptions = <Widget>[
                 HomeSubScreen(healthData),
              ];
        });


      }

推荐答案

我给您关于它的一般概念.

I'm giving you general idea of it.

@override
void initState() {
  super.initState();

  function().then((int value) {
    // future is completed you can perform your task 
  });

  function2(); // or you can simply call the method if you don't want anything to do after future completes
}

Future<int> function() async {
  // do something here 
}

Future<int> function2() async {
  // do something here
}

这篇关于如何在initState中等待异步的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！