Android Fragment

Android Fragment

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  Android Fragment 2012/11/19 John
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  Fragment A Fragment representsa behavior or a portion of user interface in an Activity. You can combine multiple fragments in a single activity to build a multi-pane UI and reuse a fragment in multiple activities. You can think of a fragment as a modular section of an activity, which has its own lifecycle, receives its own input events, and which you can add or remove while the activity is running (sort of like a "sub activity" that you can reuse in different activities). A 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 destroyed, so are all fragments. However, while an activity is running (it is in the resumed lifecycle state), you can manipulate each fragment independently, such as add or remove them. When you perform such a fragment transaction, you can also add it to a back stack that's managed by the activity—each back stack entry in the activity is a record of the fragment transaction that occurred. The back stack allows the user to reverse a fragment transaction (navigate backwards), by pressing the Back button.
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  Design Philosophy For example—tocontinue with the news application example—the application can embed two fragments in Activity A, when running on a tablet-sized device. However, on a handset-sized screen, there's not enough room for both fragments, so Activity A includes only the fragment for the list of articles, and when the user selects an article, it starts Activity B, which includes the second fragment to read the article. Thus, the application supports both tablets and handsets by reusing fragments in different combinations, as illustrated in figure 1.
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  Creating a Fragment Tocreate a fragment, you must create a subclass of Fragment (or an existing subclass of it). The Fragment class has code that looks a lot like an Activity. It contains callback methods similar to an activity, such as onCreate(), onStart(), onPause(), and onStop(). In fact, if you're converting an existing Android application to use fragments, you might simply move code from your activity's callback methods into the respective callback methods of your fragment.
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  Handling the FragmentLifecycle Also like an activity, you can retain the state of a fragment using a Bundle, in case the activity's process is killed and you need to restore the fragment state when the activity is recreated. You can save the state during the fragment's onSaveInstanceState() callback and restore it during either onCreate(), onCreateView(), or onActivityCreated(). For more information about saving state, see the Activities document.
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  Three Type View(in our project) I (Fragment) II (Layout View) III (DialogFragment)
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  Three Type View(in our project) ● There's view all in the same Activity. ● View control by Activity. ● Every data transaction with controller need to over the Activity as your view's controller.
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  Three Type View(in our project) View Type Control Help Guide Page I (Fragment) Activity Channel list Page Program Info Page Schedule Record Page Schedule List Page Startup Page Play list Page EPG Search II (DialogFragment)Subtitle Subaudio Parental Control Error Message III (Layout View)
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  References web site AndroidDevelop Guide Fragment: http://developer.android.com/guide/components/fragments.html Supporting Multiple Screen: http://developer.android. com/guide/practices/screens_support.html Blog Fragment中文: http://leybreeze.com/blog/?p=902 Merge: http://zhuyonghui116.blog.hexun.com.tw/49165333_d.html Include: http://158067568.iteye.com/blog/932206