Called when the activity is first created. This is where you should do all of your normal static set up: create views, bind data to lists, etc. This method also provides you with a Bundle containing the activity's previously frozen state, if there was one.
Always followed by onStart().
//当activity第一次被创建的时候调用。你应该在这个方法里进行所有的静态创建，创建views，（通过setContnetView方法）向lists绑定数据等等。如果存在保存的状态的话，该方法也提供给你一个包含activity最近状态的一个bundle。onStart方法总是在此方法之后调用
onRestart() 次状态下activity不可被终结
Called after your activity has been stopped, prior to it being started again.
Always followed by onStart()
//在你的activity停止后被调用，在重新开始之前调用
onResume() 次状态下activity不可被终结
Called when the activity will start interacting with the user. At this point your activity is at the top of the activity stack, with user input going to it.
Always followed by onPause().
//当activity将被启动与用户交互的时候被调用。此刻你的activity处于activity栈的顶端，用于用户输入，永远///在onPause之后被调用
onPause() 次状态下activity不可被终结 ，android HoneyComb系统除外
Called when the system is about to start resuming a previous activity. This is typically used to commit unsaved changes to persistent data, stop animations and other things that may be consuming CPU, etc. Implementations of this method must be very quick because the next activity will not be resumed until this method returns.
Followed by either onResume() if the activity returns back to the front, or onStop() if it becomes invisible to the user.
//当系统即将重新开始以前的activity的时候被调用（不懂，自己的理解是：当当前activity要启动新的activity的时候被调用），典型的应用是用来将还未保存的数据提交到当前的数据，（意思就是保存数据更新），停止animations和其他可能耗费CPU的操作。对此方法的实现必须快速因为下个activity直到此方法返回才会被重新开始。
当activity从back（翻译后台不合适）转到front（与用户交互的状态）的时候，onResume方法会在onPause方法之后被调用
当activity变为不可见的时候，onStop方法会在onPause之后被调用
onStop() 次状态下activity可以被终结
Called when the activity is no longer visible to the user, because another activity has been resumed and is covering this one. This may happen either because a new activity is being started, an existing one is being brought in front of this one, or this one is being destroyed.
