在android源碼中的描述是:
* 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 <application> tag, which will cause that class
* to be instantiated for you when the process for your application/package is
* created.
在SDK中的描述:
Application類是為了那些需要保存全局變量設計的基本類,可以在AndroidManifest.xml的<application>標簽中進行自己的實現,這樣的結果是:當application或者包被建立的時候將引起那個類被建立。