摘要：http://developer.android.com/guide/components/fragments.html1. Fragments A Fragment represents a behavior or a portion of the user interface in an Activity. a modular section of an activity. A Fragment must always be embedded in an activity, and its lifecycle is directly affected by the host activit 阅读全文

摘要：http://developer.android.com/guide/components/activities.html1. Activities Each activity is given a window in which to draw its user interface. The window typically fills the screen, but may be smaller than the screen and float on top of other windows. Tipycally, one activity in an application is s. 阅读全文

摘要：http://developer.android.com/guide/components/fundamentals.html1. APP Fundmentals (1) Android is a multi-user Linux system in which each application is a different user. (2) By default, the system sets each application a unique Linux user ID (used only by the system, unknown to theapplication) sets 阅读全文