Fragment 之间的传值

以我目前的水平，所能自己创造的类和类之间的传值基本上都是通过接口进行，例如使用异步任务AsyncTask 进行数据的加载 之后将数据通过接口回调的形势回传给activity 或者Fragment 来进行UI的更新
1. 首先建立接口，这个步骤可以在Fragment 内部实现也可以自己单独在其他实现,然后在其中一个Fragment 内部定义接口的对象

   public class HeadlinesFragment extends ListFragment {OnHeadlineSelectedListener mCallback;// Container Activity must implement this interfacepublic interface OnHeadlineSelectedListener {    public void onArticleSelected(int position);}@Overridepublic void onAttach(Activity activity) {    super.onAttach(activity);    // This makes sure that the container activity has implemented    // the callback interface. If not, it throws an exception    try {        mCallback = (OnHeadlineSelectedListener) activity;    } catch (ClassCastException e) {        throw new ClassCastException(activity.toString()                + " must implement OnHeadlineSelectedListener");    }}

1. 让Activity实现这个接口，并在Fragment 的OnAttach 方法把activity对象强转为接口对象

   public static class MainActivity extends Activity
   implements HeadlinesFragment.OnHeadlineSelectedListener{
   …

   public void onArticleSelected(int position) {
   // The user selected the headline of an article from the HeadlinesFragment
   // Do something here to display that article
   }

3.传递消息
public static class MainActivity extends Activity
implements HeadlinesFragment.OnHeadlineSelectedListener{
…

public void onArticleSelected(int position) {    // The user selected the headline of an article from the HeadlinesFragment    // Do something here to display that article    ArticleFragment articleFrag = (ArticleFragment)            getSupportFragmentManager().findFragmentById(R.id.article_fragment);    if (articleFrag != null) {        // If article frag is available, we're in two-pane layout...        // Call a method in the ArticleFragment to update its content        articleFrag.updateArticleView(position);    } else {        // Otherwise, we're in the one-pane layout and must swap frags...        // Create fragment and give it an argument for the selected article        ArticleFragment newFragment = new ArticleFragment();        Bundle args = new Bundle();        args.putInt(ArticleFragment.ARG_POSITION, position);        newFragment.setArguments(args);        FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();        // Replace whatever is in the fragment_container view with this fragment,        // and add the transaction to the back stack so the user can navigate back        transaction.replace(R.id.fragment_container, newFragment);        transaction.addToBackStack(null);        // Commit the transaction        transaction.commit();    }}

}