问题描述
I am a little bit confused about the ComponentName class in Android.
There are different ways to get to a component name object, but I don't know when to use which... and why!
Example:
- Application package is
de.zordid.sampleapp
- but widget provider class is
de.zordid.sampleapp.widget.WidgetProvider
Using
ComponentName cn = new ComponentName("de.zordid.sampleapp.widget",
"WidgetProvider");
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??
Using
ComponentName cn = new ComponentName(context, WidgetProvider.class);
yields ComponentInfo{de.zordid.sampleapp/de.zordid.sampleapp.widget.WidgetProvider}
- and that works fine!!
There is even another way to get a ComponentName - by context and a string. Which one should be used where and when??
Thanks!
The ComponentName
constructor taking two String
s 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");
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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