M - V - X ?

• MVC
• MVP
• MVVM

MVC

• Model
• 資料：資料庫
• 狀態：畫面上的值
• 邏輯運算：單位換算、資料格式
• View
• 畫面的呈現
• 又或是說，邏輯結果
• Controller
• Model 和 View 的溝通橋樑

MVP

• Model
• View
• Presenter
• 不需要一邊處理 UI 的事情，一邊忙著執行各種動作

MVVM

• Model
• View
• ViewModel

Activity Lifecycle - Starts

• onCreate()
• Called when the activity is first created.
• onStart()
• Called when the activity is becoming visible to the user.
• onResume()
• Called when the activity begins interacting with user.

Activity Lifecycle - Running

• If an activity in the foreground of the screen (at the top of the stack), it is active or running.
• onPause()
• The activity is no longer visible. Commit unsaved changes.

Activity Lifecycle - Paused

• If an activity has lost focus but is still visible (that is, a new non-full-sized or transparent activity has focus on top of your activity), it is paused.
• A paused activity is completely alive, but can be killed by the system in extreme low memory situations.
• onStop()
• The activity is no longer visible beacuse another activity is active.

Activity Lifecycle - Stopped

• If an activity is completely obscured by another activity, it is stopped.
• It still retains all state and member information, however, it is no longer visible to the user and it will often be killed by the system when memory is needed elsewhere.
• onDestroy()
• The final call before the activity is destroyed.

Activity Lifecycle - Destroyed

• If an activity is paused or stopped, the system can drop the activity from memory by either asking it to finish, or simply killing its process.
• When it is displayed again to the user, it must be completely restarted and restored to its previous state.