使用Application Context是什么意思？ [英] What exactly does using the Application Context mean?

问题描述

我很新，对不起，如果这是一个非常愚蠢的问题。我只是想澄清一些事情。我的书说我可以通过使用 getApplicationContext（）方法来检索进程的应用程序上下文。我只是真的不知道在哪里输入这个或什么做任何它。我可以去层次结构，但是我该如何处理所有脚本。还要在main.xml中写入Activity Callbacks？一个练习要我给我的项目添加一个日志记录，但是我不知道该怎么做。确切的文字说：

I'm new to this and I'm sorry if this is a really dumb question. I'm just trying to clarify things. My book says I can retrieve application context for process by using the getApplicationContext() method. I just really don't know where to type this or what to do with any of it. I can go to the hierarchy but what do I do with all the script there. Also where would I write Activity Callbacks, in the main.xml? An exercise wants me to add a logging tag to my project but I'm not sure how to do this. The exact text says:

在onCreate（）回调方法中，使用Log.i（）方法添加一个信息性日志消息。

"Within the onCreate() callback method, add an informational logging message, using the Log.i() method."

另一个练习说：

除了onCreate（）之外还实现了一些Activity回调方法，比如onStart（），向每个回调方法添加一个日志消息，然后正常运行应用程序。

"Implement some of the Activity callback methods in addition to onCreate(), such as onStart(). Add a log message to each callback method and then run the application normally".

由于这些似乎是基本问题，有人可以帮助我。

As these seem like basic questions, can someone please help me.

我正在使用Android SDK和Eclipse。我已经做了Hello World应用程序，但我不知道如何处理上下文或检索资源。请帮助！

I am using the Android SDK, and Eclipse. I have made the Hello World application, but I have no idea what to do with Context or Retrieving resources. Please help!

推荐答案

我会给你的第一条规则：如果你不知道你为什么需要它，你可能会不需要它在需要上下文时，使用您的活动对象作为上下文。

The first rule I would give you: if you don't know why you need it, you probably don't need it. Use your activity object as the Context when you need a context.

您谈论的回调是在Activity类上。应用程序基础知识描述了一个活动： http://developer.android.com/指导/主题/ fundamentals.html＃组件

The callbacks you talk about are on the Activity class. The Application Fundamentals describes what an Activity is: http://developer.android.com/guide/topics/fundamentals.html#Components

只有当您需要存在于生命周期之外的上下文时，才需要使用getApplicationContext（）的Activity类（或其他组件）。您将需要查找有关特定情况的文档，这些情况需要，有很多浮动。例如，这是Android文档的一部分： http：// android-developers.blogspot.de/2009/01/avoiding-memory-leaks.html

The only time you want to use getApplicationContext() is when you need a Context that exists outside of the lifecycle of an Activity class (or other component). You'll want to find documentation on specific cases where this is desired, there is a lot floating around. For example this one is part of the Android documentation: http://android-developers.blogspot.de/2009/01/avoiding-memory-leaks.html

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