何时在Android中为ComponentName使用哪个构造函数？ [英] When to use which constructor for ComponentName in Android?

问题描述

我对Android中的ComponentName类有点困惑。

I am a little bit confused about the ComponentName class in Android.

有多种方法可以获取组件名称对象，但是我不知道何时使用哪个...以及为什么！

There are different ways to get to a component name object, but I don't know when to use which... and why!

示例：

• 应用程序包是 de.zordid.sampleapp


• ，但窗口小部件提供程序类是 de.zordid.sampleapp.widget.WidgetProvider

• Application package is de.zordid.sampleapp
• but widget provider class is de.zordid.sampleapp.widget.WidgetProvider

使用

ComponentName cn = new ComponentName("de.zordid.sampleapp.widget",
    "WidgetProvider");

我得到了以下组件信息： ComponentInfo {de.zordid.sampleapp.widget / WidgetProvider} ，但我无法使用它-组件未知！
但是JavaDoc说我应该给程序包和该程序包中的类-这就是我所做的，不是吗？

I got this component info: ComponentInfo{de.zordid.sampleapp.widget/WidgetProvider}, but I could not use this - the component is unknown! But the JavaDoc says I should give the package and the class within that package - and that is what I did, didn't I??

使用

ComponentName cn = new ComponentName(context, WidgetProvider.class);

收益 ComponentInfo {de.zordid.sampleapp / de.zordid.sampleapp。 widget.WidgetProvider} -很好！！

甚至还有另一种获取ComponentName的方法-通过上下文和字符串。
应该在何时何地使用哪个？？

There is even another way to get a ComponentName - by context and a string. Which one should be used where and when??

谢谢！

推荐答案

带有两个 String 的 ComponentName 构造函数可用于引用另一个应用程序中的组件。但是，第一个参数不是类的包名称；它是应用程序的程序包名称--该应用程序<$ c中清单元素的 package 属性$ c> AndroidManifest.xml 。因此，第一个示例应该是

The ComponentName constructor taking two Strings can be used to refer to a component in another application. But, the first argument is not the package name of the class; it is the package name of the application---the package attribute of the manifest element in that application's AndroidManifest.xml. So your first example should be

ComponentName cn = new ComponentName("de.zordid.sampleapp",
    "de.zordid.sampleapp.widget.WidgetProvider");

该构造函数当然可以用于引用您自己的应用程序中的组件，但是由于您已经拥有您自己的应用程序中的 Context ，您不妨使用它并使用其他构造函数之一。我认为，使用 Class 的人应该是首选。如果由于某种原因仅动态知道该类，则可以使用带有 String 的那个。在这种情况下，应使用上述完全限定的类名称。

That constructor could certainly be used to refer to components in your own application, but since you already have hold of a Context from your own application you might as well use it and use one of the other constructors. In my opinion, the one taking a Class should be preferred whenever usable. You could use the one taking a String if you only know the class dynamically for some reason; in that case, it should take the fully-qualified class name as above.

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