如何在Fragment之间传递数据？

对于所有那些投反对票并投票决定关闭这个问题的人，认为它与 textview 的范围有关......然后看看，它与 textview 的范围无关

无法在片段之间传递数据，应用程序崩溃，我不知道我做错了什么...我点击了此链接http://manishkpr.webheavens.com/android-passing-data- Between-fragments/ http://manishkpr.webheavens.com/android-passing-data-between-fragments/

这是我正在使用的代码 片段A（该片段正在传递数据）

public class FragmentSongs extends  Fragment implements Serializable,OnFragmentCreatedListener {
ListView SngList;


 ArrayList<SongDetails> Songinfo=null;
AdapterView.AdapterContextMenuInfo info;

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
    Bundle savedInstanceState) 
{

    ViewGroup view = (ViewGroup) inflater.inflate(R.layout.fragment_song, null);

    SngList = (ListView) view.findViewById(R.id.SongList);
    registerForContextMenu(SngList);
    //File f=new File(Environment.getExternalStorageDirectory()+"/Music");
    File f=new File("/system/");
    int j=0;int i=0;

    getActivity().setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);

      Songinfo = getSongsFromDirectory(f);



    //sorting done below
    if (Songinfo.size()>0)
    {

        for( j=0; j<Songinfo.size();j++)
        {
            for ( i=j+1 ; i<Songinfo.size(); i++)
            { 
                SongDetails a=Songinfo.get(i);
                SongDetails b=Songinfo.get(j);
                if(a.getSong().toLowerCase().compareTo(b.getSong().toLowerCase())<0)
                {   

                    Songinfo.set(i,b );
                    Songinfo.set(j,a);
                }
            }

        }






   SngList.setAdapter(new CustomAdapter(Songinfo));
   return view;
    }
    else return null;

}
OnFragmentCreatedListener listener;
@Override
public void onAttach(Activity activity) {
    super.onAttach(activity);
    try {
        listener = (OnFragmentCreatedListener) getActivity();
        listener.onFragmentCreated(Songinfo);
    } catch (ClassCastException e) {
        throw new ClassCastException(activity.toString() + " must implement onFragmentCreated");
    }
}

片段B（接收者片段）

    public class FragmentArtists extends Fragment {
    ArrayList<SongDetails> songinfo2;
ViewGroup view;
int s=5;//TextView text;
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState)
{Context context;
LayoutInflater lf = getActivity().getLayoutInflater();   

    view = (ViewGroup) inflater.inflate(R.layout.fragment_artist,  null);
// view =  lf.inflate(R.layout.test,container, false);
// view = inflater.inflate(R.layout.test,container, false);


 s=s+5;
//     text=(TextView)view.findViewById(R.id.tt);when i use this,it works fine but i want to do it in the other method

//text.setText("makzzz");when i use this,it works fine but i want to do it in the other method
return view;

}

 void setSongList(ArrayList<SongDetails> songinfo) 
{    //TextView text=(TextView)this.getView().findViewById(R.id.tt);//when i used this view was not global
      TextView text=(TextView)view.findViewById(R.id.tt);//when i used this,view was global;
      //TextView text=(TextView)view.findViewById(R.id.tt);
    // text=(TextView)super.getView().findViewById(R.id.tt);


     text.setText("makzzz");

持有者活动中的方法（此活动持有片段）

protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.mymusic);


           fragments = new Vector<Fragment>();
            fragments.add(Fragment.instantiate(this, FragmentSongs.class.getName()));
            fragments.add(Fragment.instantiate(this, FragmentArtists.class.getName()));
            fragments.add(Fragment.instantiate(this, FragmentPlaylists.class.getName()));
            fragments.add(Fragment.instantiate(this, FragmentAlbums.class.getName())); 


            ViewPagerAdapter adapter = new ViewPagerAdapter(super.getSupportFragmentManager(), fragments);


            ViewPager pager = (ViewPager)super.findViewById(R.id.viewpager);



            pager.setAdapter(adapter);
            pager.setOffscreenPageLimit(4);

            pager.setCurrentItem(0);

    }      public void onFragmentCreated(ArrayList<SongDetails> msg) {
            FragmentArtists Obj=(FragmentArtists)  fragments.get(1);
            Obj.setSongList(msg);
            }

    }

回调类：

package sourcecode.jazzplayer;

import java.util.ArrayList;

public interface OnFragmentCreatedListener {
    public void onFragmentCreated(ArrayList<SongDetails> msg);

}

这是日志猫

  09-19 23:50:46.851: E/AndroidRuntime(2125): java.lang.NullPointerException
09-19 23:50:46.851: E/AndroidRuntime(2125):     at sourcecode.jazzplayer.FragmentArtists.setSongList(FragmentArtists.java:55)
09-19 23:50:46.851: E/AndroidRuntime(2125):     at sourcecode.jazzplayer.MyMusic.onFragmentCreated(MyMusic.java:45)
09-19 23:50:46.851: E/AndroidRuntime(2125):     at sourcecode.jazzplayer.FragmentSongs.onAttach(FragmentSongs.java:128)
09-19 23:50:46.851: E/AndroidRuntime(2125):     at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:883)
09-19 23:50:46.851: E/AndroidRuntime(2125):     at android.support.v4.app.FragmentManagerImpl.performPendingDeferredStart(FragmentManager.java:823)
09-19 23:50:46.851: E/AndroidRuntime(2125):     at android.support.v4.app.Fragment.setUserVisibleHint(Fragment.java:819)
09-19 23:50:46.851: E/AndroidRuntime(2125):     at android.support.v4.app.FragmentPagerAdapter.setPrimaryItem(FragmentPagerAdapter.java:130)
09-19 23:50:46.851: E/AndroidRuntime(2125):     at android.support.v4.view.ViewPager.populate(ViewPager.java:1066)
09-19 23:50:46.851: E/AndroidRuntime(2125):     at android.support.v4.view.ViewPager.populate(ViewPager.java:914)
09-19 23:50:46.851: E/AndroidRuntime(2125):     at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1436)
09-19 23:50:46.851: E/AndroidRuntime(2125):     at android.view.View.measure(View.java:12603)
09-19 23:50:46.851: E/AndroidRuntime(2125):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4677)
09-19 23:50:46.851: E/AndroidRuntime(2125):     at android.widget.FrameLayout.onMeasure(FrameLayout.java:293)
09-19 23:50:46.851: E/AndroidRuntime(2125):     at android.view.View.measure(View.java:12603)
09-19 23:50:46.851: E/AndroidRuntime(2125):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4677)
09-19 23:50:46.851: E/AndroidRuntime(2125):     at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1369)
09-19 23:50:46.851: E/AndroidRuntime(2125):     at android.widget.LinearLayout.measureVertical(LinearLayout.java:660)
09-19 23:50:46.851: E/AndroidRuntime(2125):     at android.widget.LinearLayout.onMeasure(LinearLayout.java:553)
09-19 23:50:46.851: E/AndroidRuntime(2125):     at android.view.View.measure(View.java:12603)
09-19 23:50:46.851: E/AndroidRuntime(2125):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4677)
09-19 23:50:46.851: E/AndroidRuntime(2125):     at android.widget.FrameLayout.onMeasure(FrameLayout.java:293)
09-19 23:50:46.851: E/AndroidRuntime(2125):     at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2072)
09-19 23:50:46.851: E/AndroidRuntime(2125):     at android.view.View.measure(View.java:12603)
09-19 23:50:46.851: E/AndroidRuntime(2125):     at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1044)
09-19 23:50:46.851: E/AndroidRuntime(2125):     at android.view.ViewRootImpl.handleMessage(ViewRootImpl.java:2418)
09-19 23:50:46.851: E/AndroidRuntime(2125):     at android.os.Handler.dispatchMessage(Handler.java:99)
09-19 23:50:46.851: E/AndroidRuntime(2125):     at android.os.Looper.loop(Looper.java:137)
09-19 23:50:46.851: E/AndroidRuntime(2125):     at android.app.ActivityThread.main(ActivityThread.java:4340)
09-19 23:50:46.851: E/AndroidRuntime(2125):     at java.lang.reflect.Method.invokeNative(Native Method)
09-19 23:50:46.851: E/AndroidRuntime(2125):     at java.lang.reflect.Method.invoke(Method.java:511)
09-19 23:50:46.851: E/AndroidRuntime(2125):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
09-19 23:50:46.851: E/AndroidRuntime(2125):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
09-19 23:50:46.851: E/AndroidRuntime(2125):     at dalvik.system.NativeStart.main(Native Method)

错误在这行代码中

TextView 文本=(TextView)view.findViewById(R.id.tt); //这一行位于接收者片段(fragmentArtist)中

正如我在评论中已经说过的，你正在尝试与Fragment当它尚未正确初始化时。当。。。的时候FragmentSongs附于Activity（要求采取的行动ViewPager它将出现的地方）其onAttach()方法被调用。在这个方法中，你投射了Activity给你的听众，但你也立即调用侦听器的回调。这将使您的应用程序崩溃（您发布的例外），因为在该侦听器中您正在尝试使用第二个的视图Fragment of the ViewPager, FragmentArtists. This Fragment尚未初始化，此时第一个片段ViewPager几乎没有附加到该活动，并且您已经在尝试使用第二个片段的视图，这显然会失败。

您链接到的教程很好，很简单，但是还可以（如果不转到该链接，我假设您的代码来自教程）。问题是您在更复杂的情况下使用了非常简单的场景中的代码（事实上，如果您在该教程的代码中插入当前代码，您将得到相同的异常（太早调用侦听器））。

应该在片段完全构建时使用该回调侦听器接口（例如当用户使用应用程序并选择一首歌曲并且您想向他显示应用程序的艺术家部分时（此时调用侦听器并使其通过） data)) 还仔细处理片段不可用的可能性。

如果您需要在片段生命周期的早期在片段之间传递数据，以至于无法保证片段可用（就像在onAttach()一个片段）然后实现片段来获取数据directly从活动构建时的生命周期方法之一中获取。您要传递的内容尚不清楚，因此我在这里无话可说。