java从一个片段调用另一个片段中的方法

Question

我已经尝试了一段时间（也在这里搜索），当按下其他片段中的按钮时，可以帮助我刷新MainFragment中的listView。谁能告诉我怎么做

下面是函数的main片段（我排除了其他函数，因为我不知道它们是如何贡献的）：

public class MainFragment extends Fragment {
public void otherList() {
    SQLite db = new SQLite(getActivity());
    db.open();
    Calendar sCalendar = Calendar.getInstance();
    String day = sCalendar.getDisplayName(Calendar.DAY_OF_WEEK,
            Calendar.LONG, Locale.ENGLISH);
    Cursor c = db.getAllRecords(day);
    Calendar cal = Calendar.getInstance();
    int hour = cal.get(Calendar.HOUR_OF_DAY);
    arrayOfBars.clear();
    if (c.moveToFirst()) {
        do {
            String country = c.getString(0);
            String city = c.getString(1);
            String bar = c.getString(2);
            String timeStart = c.getString(3);

            String[] h = timeStart.split(":");
            int times = Integer.parseInt(h[0]);

            String timeEnd = c.getString(4);
            String[] h2 = timeEnd.split(":");
            int timee = Integer.parseInt(h2[0]);

            String placeLaLo = c.getString(5);
            String description = c.getString(6);
            String likes = c.getString(7);
            String offer = c.getString(8);

            if (hour < (times + 1) || hour < (timee)) {
                getPrefs = PreferenceManager
                        .getDefaultSharedPreferences(MainFragment.this
                                .getActivity());
                boolean lay = getPrefs.getBoolean("boolean", false);
                if (lay == true) {
                    while (times < timee) {
                        timeStart = times + ":" + h[1];
                        times++;
                        timeEnd = times + ":" + h2[1];
                        arrayOfBars.add(new BarObject(country, city, bar,
                                timeStart, timeEnd, placeLaLo, description,
                                likes, offer, bar));
                    }
                } else {
                    arrayOfBars.add(new BarObject(country, city, bar,
                            timeStart, timeEnd, placeLaLo, description,
                            likes, offer, bar));
                }
            }

        } while (c.moveToNext());

        Collections.sort(arrayOfBars, new BarObject.CompST());

        lv2.setAdapter(null);
        adapter = new BarAdapter(getActivity(), arrayOfBars);
        lv2.setAdapter(adapter);
    } else {
        Toast.makeText(getActivity(), "No database found",
                Toast.LENGTH_LONG).show();
    }
    db.close();
}

}

这是另一个片段：

public class SocialMedia extends Fragment {
ImageButton facebook, twitter, layoutS;

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.social_media, container, false);
    layoutS = (ImageButton) view.findViewById(R.id.ibLayout);

    layoutS.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            SharedPreferences getPrefs = PreferenceManager
                    .getDefaultSharedPreferences(SocialMedia.this
                            .getActivity());
            boolean lay = getPrefs.getBoolean("boolean", false);
            SharedPreferences.Editor e = getPrefs.edit();
            lay = !lay;
            e.putBoolean("boolean", lay);
            e.commit();
                            //Here I want to call otherList() from MainFragment
        }
    });
    return view;
}

}

Answer 1

            // Calling Parent Fragment method from Child Fragment.
        // Child Fragment
        AppCompatActivity activity = (AppCompatActivity) view.getContext();
        FragmentManager fragmentManager = activity.getSupportFragmentManager();
        NavigateFragment navigateFragment = (NavigateFragment) fragmentManager.findFragmentById(R.id.fragment_place_dashboard);
        navigateFragment.sayHelloWorld();


        // -- Some method in Parent Fragment(NavigateFragment).
        public void sayHelloWorld(){
            Log.d(TAG, "Hello World.");
        }

Answer 2

你应该用interface来做这个。在OtherFragment类中定义一个interface并在MainActivity中实现，在MainFragment中定义一个public方法来刷新ListView并从MainActivity调用该方法。下面是一个例子：

public Class OtherFragment extends Fragment implements OnClickListener {

private Communicator communicator;

   ...

public void setCommunicator(Communicator communicator) {
    this.communicator = communicator;
}

@Override
public void onClick(View v) {
   communicator.clicked();
}

   public interface Communicator {
      public void clicked();
   }
}

在你的MainActivity中：

public class MainActivity extends Activity implements OtherFragment.Communicator {

   MainFragment mainFragment;

   @Override
   protected void onCreate(Bundle b) {
      ...
      OtherFragment otherFragment = new OtherFragment();
      otherFragment.setCommunicator(this);
      ...
   }

   ...

   @Override 
   public void clicked() {
     mainFragment.updateList();
   }
}

在你的MainFragment中：

public class MainFragment extends Fragment {

    ...

    public void updateList() {
        // update list
    }
}

Answer 3

要从另一个对象（片段是一个对象）调用方法，需要有该对象的引用。因此，如果您想从SocialMedia实例调用MainFragment#otherList()，那么SocialMedia需要对MainFragment的引用

例如：

public class SocialMedia {

    private MainFragment mainFragment = null;

    public void setMainFragment(final MainFragment mainFragment) {
        this.mainFragment = mainFragment
    }
}

然后你可以使用this.mainFragment.otherList()

Answer 4

在MainFragment类中，可以执行以下代码：

private static MainFragment instance = null;

@Override  
public void onCreate(@Nullable Bundle savedInstanceState) {  
    super.onCreate(savedInstanceState);  
    instance = this;  
}

public static MainFragment getInstance() {  
    return instance;  
} 

在SocialMedia类中，可以按如下方式调用该方法：

MainFragment.getInstance().otherList();   

Answer 5

FragmentManager fm = getFragmentManager(); 
MainFragment fragm = (MainFragment)fm.findFragmentById(R.id.main_fragment); 
fragm.otherList(); 

这个代码最适合我。看起来很容易