使用Tab和onTabSelected（）時如何在片段之間傳遞數據？

Question

本教程涉及片段之間的通信，但不針對選項卡進行通信。 我想從“選項卡”的“ Daycare”片段到也是選項卡的“ You”片段之間發送數據。 我已經堅持了一個星期。 我真的不知道如何將接口的概念與android選項卡式片段和asynctasks中的數據結合起來。

我在Daycare片段中創建了一個接口。 我想借助“ passparam”方法將字符串“ daycarename”發送到“ you”片段。 據我了解，它需要以某種方式通過MainActivity來實現我的TabClickedListener接口。 如何將其從MainActivity傳遞回另一個片段？

public class MainActivity extends Activity implements ActionBar.TabListener, DaycareFragment.TabClickedListener {

    SectionsPagerAdapter mSectionsPagerAdapter;
    ViewPager mViewPager;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        final ActionBar actionBar = getActionBar();
        actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);

        mSectionsPagerAdapter = new SectionsPagerAdapter(getFragmentManager(), this);

        mViewPager = (ViewPager) findViewById(R.id.pager);
        mViewPager.setAdapter(mSectionsPagerAdapter);

         mViewPager.setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
            @Override
            public void onPageSelected(int position) {
                actionBar.setSelectedNavigationItem(position);
            }
        });

         for (int i = 0; i < mSectionsPagerAdapter.getCount(); i++) {
            actionBar.addTab(
                actionBar.newTab()
                    .setText(mSectionsPagerAdapter.getPageTitle(i))
                    .setTabListener(this));
        }
    }

    @Override
    public void onTabSelected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) {
        mViewPager.setCurrentItem(tab.getPosition());
    }

   public class SectionsPagerAdapter extends FragmentPagerAdapter {

    public SectionsPagerAdapter(FragmentManager fm) {

        super(fm);
    }

    @Override
    public Fragment getItem(int position) {

        switch (position) {
            case 0:

                return new YouFragment();
            case 1:

                return new DaycareFragment();
            case 2:

                return new ThirdFragment();

        }

        return null;
    }

    @Override
    public int getCount() {
        // Show 3 total pages.
        return 3;
    }

    @Override
    public CharSequence getPageTitle(int position) {
        Locale l = Locale.getDefault();
        switch (position) {
            case 0:
                return getString(R.string.title_section3).toUpperCase(l);
            case 1:
                return getString(R.string.title_section1).toUpperCase(l);
            case 2:
                return getString(R.string.title_section2).toUpperCase(l);

        }
        return null;
    }
}

    public class MainFragment extends Fragment {

        private static final String ARG_SECTION_TYPE = "section type";

        public MainFragment(){}

        public MainFragment(int sectionNumber) {
            Bundle args = new Bundle();
            args.putInt(ARG_SECTION_TYPE, sectionNumber);
            setArguments(args);
        }

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
            View rootView = inflater.inflate(R.layout.fragment_main, container, false);

            //setup the view
            switch(getArguments().getInt(ARG_SECTION_TYPE)) {
                //hide or show fields based on page number.
            }

            return rootView;
        }
    }
    @Override
    public void passParam(String var) {
        Toast.makeText(this, "Clicked " + var, Toast.LENGTH_LONG).show();

    }
}

我在我的ListFragment中實現一個接口：

public class DaycareFragment extends ListFragment {

    TabClickedListener listener;

    public interface TabClickedListener {
        public void passParam(String var);
    }
String email;
    UserFunctions userFunctions;
    Boolean owner;
@Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {

        View rootView = inflater.inflate(R.layout.fragment_daycare, container, false);
        movies = new ArrayList<HashMap<String, String>>();

        userFunctions = new UserFunctions();
        HashMap map = new HashMap();
        map = userFunctions.getdauser(getActivity());
        email = (String) map.get("email");

        new GetDaDaycares().execute();

        return rootView;
    }
class GetDaDaycares extends AsyncTask<String, String, String>{

        @Override
        protected void onPreExecute() {
            super.onPreExecute();

        }


        @Override
        protected String doInBackground(String... args) {

            String city = "london";
            try {

                List<NameValuePair> params = new ArrayList<NameValuePair> ();
                params.add(new BasicNameValuePair("city", city));

                @SuppressWarnings("unused")
                JSONObject json = parser.makeHttpRequest(getdaycare, params);
                jArray = json.getJSONArray("lTable");

                for (int i =0; i<jArray.length();i++){

                    JSONObject c = jArray.getJSONObject(i);
                    String daycarename = c.getString("daycarename");

                    HashMap<String, String> map = new HashMap<String, String>();
                    map.put("daycarename", daycarename);
                    movies.add(map);

                }

            } catch(JSONException e) {

                e.printStackTrace();
            }
            return null;

        }

        protected void onPostExecute(String zoom){
            pDialog.dismiss();

            getActivity().runOnUiThread(new Runnable() {
                public void run() {


                    ListAdapter adapter = new SimpleAdapter(getActivity(), movies,
                            R.layout.list, new String[] {"daycarename"},
                            new int[]{R.id.textView1});

                    setListAdapter(adapter);
                    ListView lv = getListView();
                    lv.setOnItemClickListener(new OnItemClickListener(){

                        @Override
                        public void onItemClick(AdapterView<?> parent, View view, int position,
                                                long id) {

                            String daycarename =movies.get(position).get("daycarename");

                        }

                    });


                }
            });
        }

    }

}

Answer 1

如果這是我的問題（一直是），那么我將有一個中心對象負責片段之間的“共享”數據。

該實現通常似乎遵循2條路徑中的1條：一種，創建任何對象都可以獲取一個實例的單例，或兩種活動將對象的單個實例初始化，並在初始化時將其傳遞給每個片段。

然后，片段（或AsyncTask）將通過“觀察者模式”或在顯示器上更新並從該中央對象中提取數據，但是您需要這樣做。

ps如果要在一個片段中包含一個AsyncTask，則將要實現一種策略，以確保UI完成時不會死。 否則，您可以引發異常。

pps onPostExecute默認情況下在UI線程上運行。

Answer 2

在您的Activity ：

public void passStrToYou(String daycarename)
{
   FragmentManager fm = getFragmentManager();               
   Fragment youFrag = (YouFragment)fm.FragmentManager fm.findFragmentById(R.id.youFragment);

   //call mathod 'setDayCareName' in 'you' fragment
   youFrag.setDayCareName(daycarename);
}

希望對您有所幫助！