android.app.Application

在Study NDK的章節裡,看到sample用到Application,之前沒看過這個東西,基本上,


http://developer.android.com/reference/android/app/Application.html

給的定義如下


Base class for those who need to maintain global application state. You can provide your own implementation by specifying its name in your AndroidManifest.xml's tag, which will cause that class to be instantiated for you when the process for your application/package is created.


其實, application的角色可以從AndroidManifest.xml裡的結構就可以看出來


manifest
---application
------activity


activity是包在application裡面的, 只是我們只把application當作一個殼, 在這個sample是將這個殼加了一個儲藏室,只要多定義


android:name=".UA2EFindEdgesApp"


 然後實做


public class UA2EFindEdgesApp extends Application


這樣在整個application所包圍的區域,都可以利用 


UA2EFindEdgesApp app = (UA2EFindEdgesApp) getApplication();


取用這個application所增加的功能,以書上的例子是藉此存取系統共用的Bitmap