为什么getCallingActivity总是返回null？ [英] Why is getCallingActivity always returning null?

问题描述

我可以在我的应用程序启动的第一个活动欢迎画面，也可以由用户花费的时间。我希望它采取行动时，它从家庭开始略有不同的主要活动启动屏幕（或任何其他应用程序）或主要活动

I have a welcome screen that can be started as the first activity in my app, or it can be started by the main activity that the user spends their time in. I want it to act slightly differently when it's started from the home screen (or any other app) or the main activity.

调用 getCallingActivity（）中的onCreate似乎总是返回空值，不管是什么所谓的活动。这是奇怪的，因为它的工作较早，这是我发现了什么格式的字符串返回（这应该是在文档中是这样）。我看不出有什么可能影响它，因为调用之前出现这种情况的唯一的事情 getCallingActivity（）呼吁 super.onCreate（savedInstanceState）。我打电话跟 startActivityForResult（welcomeIntent，RESULT_WELCOME）。

Calling getCallingActivity() in onCreate seems to always return null, regardless of what called the activity. This is strange, because it did work earlier, which is how I found what format the string returns in (which should be in the documentation anyway). I can't see what could have affected it, because the only thing that happens before calling getCallingActivity() is calling super.onCreate(savedInstanceState). I am calling the activity with startActivityForResult(welcomeIntent, RESULT_WELCOME).

我是什么做错了吗？是否有其他方式来获得这些信息？

What am I doing wrong? Is there an alternative way to get this info?

推荐答案

传递一个额外的意图与 startActivityForResult（）使用，说明你想要的模式。阅读额外通过 getIntent（）。getXXXExtra（）（ XXX 要看你选择什么样的数据类型）的的onCreate（）新开工活动。

Pass an extra in the Intent used with startActivityForResult(), indicating which mode you want. Read that extra via getIntent().getXXXExtra() (XXX depends on what data type you choose) in onCreate() of the newly-started activity.

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