Fragmenty Androida muszą być statyczne.

Question

Mam ten błąd, ale nie wiem, jak rozwiązać ten błąd.

Error: Fragments should be static such that they can be re-instantiated by the system, and anonymous classes are not static [ValidFragment]

Proszę mi pomóc, jeśli wiesz, jak rozwiązać

To MainActivity.java

import android.annotation.TargetApi; 
import android.app.ProgressDialog; 
import android.content.BroadcastReceiver; 
import android.content.Context; 
import android.content.DialogInterface; 
import android.content.Intent; 
import android.content.IntentFilter; 
import android.content.SharedPreferences; 
import android.content.res.ColorStateList; 
import android.content.res.Configuration; 
import android.graphics.Color; 
import android.os.Build; 
import android.os.Bundle; 
import android.preference.PreferenceManager; 
import android.support.design.widget.FloatingActionButton; 
import android.support.design.widget.NavigationView; 
import android.support.design.widget.Snackbar; 
import android.support.design.widget.TabLayout; 
import android.support.v4.app.Fragment; 
import android.support.v4.app.FragmentManager; 
import android.support.v4.app.FragmentPagerAdapter; 
import android.support.v4.content.LocalBroadcastManager; 
import android.support.v4.view.GravityCompat; 
import android.support.v4.view.ViewPager; 
import android.support.v4.widget.DrawerLayout; 
import android.support.v7.app.ActionBar; 
import android.support.v7.app.AlertDialog; 
import android.support.v7.app.AppCompatActivity; 
import android.support.v7.widget.Toolbar; 
import android.util.Log; 
import android.view.Menu; 
import android.view.MenuItem; 
import android.view.View; 
import android.widget.TextView; 
import android.widget.Toast; 


import com.google.android.gms.common.ConnectionResult; 
import com.google.android.gms.common.GoogleApiAvailability; 

import org.json.JSONArray; 
import org.json.JSONException; 
import org.json.JSONObject; 

import java.util.ArrayList; 
import java.util.List; 

public class MainActivity extends AppCompatActivity { 

    private DrawerLayout mDrawerLayout; 
    private String keyPref = "test"; 
    private SharedPreferences pref; 
    private static SharedPreferences.Editor editor; 
    private static ViewPager view; 

    private FoodListFragment makanan = new FoodListFragment() { 
     @Override 
     public void doRefresh() { 
      updateData(); 
     } 
    }; 
    private FoodListFragment minuman = new FoodListFragment() { 
     @Override 
     public void doRefresh() { 
      updateData(); 
     } 
    }; 
    private FoodListFragment snack = new FoodListFragment() { 
     @Override 
     public void doRefresh() { 
      updateData(); 
     } 
    }; 
    private Adapter adapter = new Adapter(getSupportFragmentManager()); 

    private static final int PLAY_SERVICES_RESOLUTION_REQUEST = 4343; 
    private BroadcastReceiver mRegistrationBroadcastReceiver; 
    private static ProgressDialog loading; 



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

     pref = getApplicationContext().getSharedPreferences(keyPref, MODE_PRIVATE); 
     editor = pref.edit(); 

     Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar); 
     setSupportActionBar(toolbar); 

     final ActionBar ab = getSupportActionBar(); 
     ab.setHomeAsUpIndicator(R.drawable.ic_menu); 
     ab.setDisplayHomeAsUpEnabled(true); 

     mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout); 

     NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view); 
     if (navigationView != null) { 
      setupDrawerContent(navigationView); 
     } 

     ViewPager viewPager = (ViewPager) findViewById(R.id.viewpager); 
     if (viewPager != null) { 
      setupViewPager(viewPager); 
     } 

     FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab); 
     fab.setBackgroundTintList(ColorStateList.valueOf(Color.rgb(183,28,28))); 
     fab.setOnClickListener(new View.OnClickListener() { 
      @TargetApi(Build.VERSION_CODES.LOLLIPOP) 
      @Override 
      public void onClick(View view) { 
       Intent intent = new Intent(getApplicationContext(), CartActivity.class); 
       MainActivity.this.startActivity(intent); 
      } 
     }); 

     TabLayout tabLayout = (TabLayout) findViewById(R.id.tabs); 
     tabLayout.setupWithViewPager(viewPager); 


     DBHelper db = new DBHelper(this); 

     mRegistrationBroadcastReceiver = new BroadcastReceiver() { 
      @Override 
      public void onReceive(Context context, Intent intent) { 
       //mRegistrationProgressBar.setVisibility(ProgressBar.GONE); 
       SharedPreferences sharedPreferences = 
         PreferenceManager.getDefaultSharedPreferences(context); 
       boolean sentToken = sharedPreferences 
         .getBoolean(QuickstartPreferences.SENT_TOKEN_TO_SERVER, false); 

      } 
     }; 


     loading = new ProgressDialog(this); 
     loading.setMessage("Loading"); 
     loading.setTitle("Menu"); 

     updateData(); 
    } 



    @Override 
    public boolean onCreateOptionsMenu(Menu menu) { 

     return true; 
    } 


    @Override 
    protected void onPause() { 
     super.onPause(); 
     LocalBroadcastManager.getInstance(this).unregisterReceiver(mRegistrationBroadcastReceiver); 
    } 

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

     LocalBroadcastManager.getInstance(this).registerReceiver(mRegistrationBroadcastReceiver, 
       new IntentFilter(QuickstartPreferences.REGISTRATION_COMPLETE)); 
    } 

    @Override 
    public boolean onOptionsItemSelected(MenuItem item) { 
     switch (item.getItemId()) { 
      case android.R.id.home: 
       mDrawerLayout.openDrawer(GravityCompat.START); 
       return true; 
     } 
     return super.onOptionsItemSelected(item); 
    } 



    public void updateData() { 

     ServerHelper server = new ServerHelper() { 
      @Override 
      public void onStart() { 
       loading.show(); 
      } 

      @Override 
      public void onFinish() { 
       loading.dismiss(); 
      } 

      @Override 
      public void onSuccess(int statusCode, String response) { 

       try { 
        editor.putString("response", response); 
        editor.commit(); 

        makanan.clearFood(); 
        minuman.clearFood(); 
        snack.clearFood(); 

        JSONArray foods = new JSONArray(response); 
        for (int i = 0; i <= foods.length()-1; i++) { 

         JSONObject object = foods.getJSONObject(i); 
         JSONObject subs = object.getJSONObject("SubCategory"); 
         FoodCategory addFood = new FoodCategory(subs.getString("name"), subs.getString("photo")); 
         if (subs.getString("categories_id").contains("1")) { 
          makanan.addFood(addFood); 
         } else if (subs.getString("categories_id").contains("2")) { 
          minuman.addFood(addFood); 
         } else if (subs.getString("categories_id").contains("3")) { 
          snack.addFood(addFood); 
         } 
        } 

        makanan.doneRefresh(); 
        minuman.doneRefresh(); 
        snack.doneRefresh(); 
       } catch (JSONException e) { 
        e.printStackTrace(); 
        Toast.makeText(view.getContext(),"Terjadi masalah koneksi, silahkan coba kembali", Toast.LENGTH_LONG).show(); 
       } 
       loading.dismiss(); 
      } 

      @Override 
      public void onFailure(int statusCode, String response) { 
       if (view != null) { 
        Snackbar.make(view, "Terjadi Masalah Koneksi", Snackbar.LENGTH_LONG) 
          .setAction("Action", null).show(); 
       } else { 
        Toast.makeText(MainActivity.this,"Terjadi Masalah Koneksi", Toast.LENGTH_LONG).show(); 
       } 
       makanan.doneRefresh(); 
       minuman.doneRefresh(); 
       snack.doneRefresh(); 
       loading.dismiss(); 
      } 
     }; 


     server.getAllSubs(); 
    } 

    private void setupViewPager(ViewPager viewPager) { 
     makanan.setRetainInstance(true); 
     minuman.setRetainInstance(true); 
     snack.setRetainInstance(true); 

     adapter.addFragment(makanan, "Makanan"); 
     adapter.addFragment(minuman, "Minuman"); 
     adapter.addFragment(snack, "Snack"); 
     viewPager.setAdapter(adapter); 

     updateData(); 
    } 

    @Override 
    public void onConfigurationChanged(Configuration newConfig) { 
     super.onConfigurationChanged(newConfig); 
    } 

    private void setupDrawerContent(final NavigationView navigationView) { 
     View header = navigationView.getHeaderView(0); 
     TextView username = (TextView) header.findViewById(R.id.main_username); 

     DBHelper db = new DBHelper(this); 
     username.setText(db.getUsers().getName()); 

     navigationView.setNavigationItemSelectedListener(
       new NavigationView.OnNavigationItemSelectedListener() { 
      @Override 
      public boolean onNavigationItemSelected(MenuItem menuItem) { 

       switch (menuItem.getItemId()) { 
        case R.id.nav_home: { 
         menuItem.setChecked(true); 
         break; 
        } 
        case R.id.nav_order: { 
         navigationView.getMenu().getItem(0).setChecked(true); 
         Intent order = new Intent(MainActivity.this, OrderActivity.class); 
         startActivity(order); 
         break; 
        } 
        case R.id.nav_cart: { 
         navigationView.getMenu().getItem(0).setChecked(true); 
         Intent cart = new Intent(MainActivity.this, CartActivity.class); 
         startActivity(cart); 
         break; 
        } 

        case R.id.nav_logout: { 
         AlertDialog.Builder dialog = new AlertDialog.Builder(MainActivity.this); 
         dialog.setMessage("Anda yakin ingin logout akun anda ?"); 
         dialog.setNegativeButton("Batal", 
           new DialogInterface.OnClickListener() { 

            @Override 
            public void onClick(DialogInterface arg0, int arg1) { 

            } 
           }); 

         dialog.setPositiveButton("Keluar", 
           new DialogInterface.OnClickListener() { 

            @Override 
            public void onClick(DialogInterface arg0, int arg1) { 
             DBHelper logout = new DBHelper(MainActivity.this); 
             logout.clearSPConfig(); 
             LocalBroadcastManager.getInstance(MainActivity.this).unregisterReceiver(mRegistrationBroadcastReceiver); 
             Intent goLogin = new Intent(MainActivity.this, LoginMainActivity.class); 
             startActivity(goLogin); 
            } 
           }); 

         AlertDialog alertDialog = dialog.create(); 
         alertDialog.show(); 

        } 
       } 
       mDrawerLayout.closeDrawers(); 
       return true; 
      } 
     }); 

    } 


    public static class Adapter extends FragmentPagerAdapter { 
     private final List<Fragment> mFragments = new ArrayList<>(); 
     private final List<String> mFragmentTitles = new ArrayList<>(); 


     public Adapter(FragmentManager fm) { 
      super(fm); 
     } 

     public void addFragment(Fragment fragment, String title) { 
      mFragments.add(fragment); 
      mFragmentTitles.add(title); 
     } 

     @Override 
     public Fragment getItem(int position) { 

      return mFragments.get(position); 
     } 

     @Override 
     public int getCount() { 
      return mFragments.size(); 
     } 

     @Override 
     public CharSequence getPageTitle(int position) { 
      return mFragmentTitles.get(position); 
     } 


    } 
} 

i jest to klasa fragment FoodListFragment.java

import android.graphics.Color; 
import android.os.Bundle; 
import android.support.annotation.Nullable; 
import android.support.annotation.UiThread; 
import android.support.design.widget.Snackbar; 
import android.support.v4.app.Fragment; 
import android.support.v4.widget.SwipeRefreshLayout; 
import android.support.v7.widget.GridLayoutManager; 
import android.support.v7.widget.RecyclerView; 
import android.util.Log; 
import android.view.InflateException; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 

import org.json.JSONArray; 
import org.json.JSONException; 
import org.json.JSONObject; 

import java.util.ArrayList; 

public abstract class FoodListFragment extends Fragment { 
    private ArrayList<FoodCategory> foodList = new ArrayList<FoodCategory>(); 
    private RecyclerView rv; 
    private RecyclerViewAdapter adapter; 
    private SwipeRefreshLayout swipeLayout; 
    private View view; 

    FoodListFragment() { 

    } 

    public void addFoods(ArrayList<FoodCategory> food) { 
     foodList = food; 
     if (adapter != null) { 
      adapter.notifyDataSetChanged(); 
     } 
    } 

    public void addFood(FoodCategory food) { 
     foodList.add(food); 
     if (adapter != null) { 
      adapter.notifyDataSetChanged(); 
     } 
    } 

    public void clearFood() { 
     foodList.clear(); 
    } 

    @Nullable 
    @Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { 
//  final RecyclerView rv = (RecyclerView) inflater.inflate(R.layout.fragment_food_list, container, false); 

     view = inflater.inflate(R.layout.fragment_food_list, null); 
     swipeLayout = (SwipeRefreshLayout) view.findViewById(R.id.swipe_container); 
     swipeLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() { 
      @Override 
      public void onRefresh() { 
       doRefresh(); 
      } 
     }); 
     swipeLayout.setColorSchemeColors(Color.RED, Color.GRAY); 

     RecyclerView rv = (RecyclerView) view.findViewById(R.id.recyclerview); 
     setupRecyclerView(rv); 

     return view; 
    } 

    private void setupRecyclerView(final RecyclerView recyclerView) { 
     //recyclerView.setLayoutManager(new LinearLayoutManager(recyclerView.getContext())); 
     recyclerView.setLayoutManager(new GridLayoutManager(recyclerView.getContext(), 2)); 
     recyclerView.setHasFixedSize(true); 

     setRetainInstance(true); 
     adapter = new RecyclerViewAdapter(getActivity(),foodList); 
     recyclerView.setAdapter(adapter); 
    } 

    public void doneRefresh(){ 
     if (swipeLayout != null) { 
      swipeLayout.setRefreshing(false); 

     } 
    } 

    public abstract void doRefresh(); 


} 

Answer 1

You deklarują twoją klasę Fragment jako . Abstract nie można utworzyć instancji klasy. Może być używany tylko jako klasa podstawowa. Sposób, w jaki próbujesz go użyć (klasa anonymous) nie jest możliwy w systemie Android. Klasa Fragment musi być podklasą Fragment (lub istniejącą podklasą) i betonem.

Usuń abstract kluczowe

public class FoodListFragment extends Fragment { 

warte swojej staramy się osiągnąć z

public abstract void doRefresh(); 

powinny być wykonane przy użyciu interfejsu.