Activity生命周期

 

单个activity生命周期：

refer: http://blog.youkuaiyun.com/android_tutor/article/details/5772285

 

Activity 的状态及状态间的转换; Activity 栈; Activity跳转及通信(intent,bundle); Intent Filter; 全屏的Activity; 把Activity设置为Dialog样式；把Activity设置为半透明的

refer: http://blog.youkuaiyun.com/zuolongsnail/article/details/6532821

 

祥细讲解生命周期中每个方法里应该做的事

refer: http://blog.youkuaiyun.com/mylzc/article/details/6738800

 

关于onSaveInstanceState () and onRestoreInstanceState ()：

onSaveInstanceState()会被调用的三种情况：
(1)如果场景一中按Home键(而不是back键)返回到主界面，那么当前Activity需要保存活动状态，因为Activity此时并未销毁，只是被放到了后台，有可能在内存紧张的时候被系统回收。

(2)当Activity遮挡时,会调用onSaveInstanceState()

(3)改变屏幕方向onSaveInstanceState()会在onPause()之前执行。

 

onRestoreInstanceState() is called only when recreating activity after it was killed by the OS. Such situation happen when:

• orientation of the device changes (your activity is destroyed and recreated)
• there is another activity in front of yours and at some point the OS kills your activity in order to free memory (for example). Next time when you start your activity onRestoreInstanceState() will be called.

onRestoreInstanceState()在onStart之后,onResume()之前执行。

 

常见用例截图：

 写两个activityA,activityB; 参考http://blog.youkuaiyun.com/mylzc/article/details/6738800

 

1，activity开启，按back:

 

2, activity开启，按home, 再启动activity:

3,启动activity，转屏幕：

4,activityA->activityB->activityA;