- 每个app 都有一个自己的 linux 进程;
- 每个进程都在自己的虚拟机里执行
- 两个app 可以跑在一个进程,一个vm里
- android app 四大组件:activity,content provider, services, broardcast receivers
- Content Resolver 激活 Content Provider
- You can start an activity (or give it something new to do) by passing an Intent to startActivity() or startActivityForResult() (when you want the activity to return a result).
- You can start a service (or give new instructions to an ongoing service) by passing an Intent to startService(). Or you can bind to the service by passing an Intent to bindService().
- You can initiate a broadcast by passing an Intent to methods like sendBroadcast(), sendOrderedBroadcast(), or sendStickyBroadcast().
- You can perform a query to a content provider by calling query() on a ContentResolver.
From <http://developer.android.com/guide/components/fundamentals.html>