felangga felangga - 6 months ago 31
Java Question

Android fragments must be static

I've got this error, but I don't know how to resolve this error.


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


Please help me if you know how to solve

This is the 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);
}


}
}


and this is the fragment class 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

You are declaring your Fragment as abstract class. Abstract class can't be instantiated. It can be used only as a base class. The way you are trying to use it (anonymous class) is not possible in Android framework. A Fragment class must be a subclass of Fragment (or an existing subclass of it) and concrete.

Remove abstract keyword

public class FoodListFragment extends Fragment {

Things your are trying to achieve with

 public abstract void doRefresh();

should be done using an interface.