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阅读：http://developer.android.com/guide/components/fragments.htmlA fragment must always be embedded in an activity and the fragment's lifecycle is directly affected by the host activity's lifecycle. For example, when the activity is paused, so are all fragments in it, and when the activity is 阅读全文
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阅读：http://developer.android.com/guide/components/activities.htmlAn application usually consists of multiple activities that are loosely bound to each other. Typically, one activity in an application is specified as the "main" activity, which is presented to the user when launching the appl 阅读全文
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阅读：http://developer.android.com/guide/components/fundamentals.htmlWhen the system starts a component, it starts the process for that application (if it's not already running) and instantiates the classes needed for the component. For example, if your application starts the activity in the camera 阅读全文
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2013.12.01更新阅读：http://www.zhihu.com/question/21074979从su说起。SU：( Switch user切换用户)，用户通过该命令可进行用户切换，该文件一般位于/system/bin或者/system/xbin/目录下，拥有者和群组均为ROOT。Linux下su以后输入密码就可以root了，但Android里的su和Linux里的su是不一样的，Android里的su不是靠验证密码的，而是看你原来的权限是什么。意思就是如果你是root，那你可以通过su切换到别的用户，比如说shell,wifi,audio什么的。但如果你是root之外的其他用户，就 阅读全文