Where to define Async class in a multi tab android project

Where to define Async class in a multi tab android project - java

I am working on an android project with three tabs (3 tabs are created using Fragment class).
I created one Async inner class in Mainactivity and calling that class from onCreate(), but nothing is happening in the Logcat. Can anyone suggest me Where to define Async class which is getting resource in JSON format. Any better way of doing this thing is also welcome.
package com.utb.iftekhar.cityweatherappsnapshot1;
public class Tab2Fragment extends Fragment {
private static final String TAG="Tab2Fragment";
private Button button;
private static final String CITY_NAME_SEARCHED="cityNameSearched";
private List<String> historyList;
private ListView historyListView;
private ArrayAdapter<String> arrayAdapter;
String cityNameSearched="";
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
View view=inflater.inflate(R.layout.tab2_frag, container, false);
historyListView=view.findViewById(R.id.historyList);
historyList=new ArrayList<>();
if(getArguments()!=null){
cityNameSearched=getArguments().getString(CITY_NAME_SEARCHED);//Not able to set values to the ctiNameSearched variable.
}else
{
Log.i("No","Arguments");//
}
if(!(cityNameSearched==null) || !cityNameSearched.equals("")){
historyList.add(cityNameSearched);
Log.i("before", cityNameSearched);
Log.i("Value in tab2frag",cityNameSearched);
}
return view;
}
//This method is returning the searched city name searched int the edit text from fragment(Tab1Fragment) but not able to access this value in cityNameSearched variable.
public void updateEditText(String newText){
Log.i("received from 1 in 2",newText);
this.cityNameSearched=newText;
}
/*
#Override
public void onAttach(Context context) {
super.onAttach(context);
if(context instanceof Tab2FragmentListener){
tab2FragmentListener=(Tab2FragmentListener)context;
}else{
throw new RuntimeException(context.toString()+
" must implement Tab2FragmentListener"
);
}
}
#Override
public void onDetach() {
super.onDetach();
tab2FragmentListener=null;
}*/
}
public class Tab1Fragment extends Fragment{
private String weatherResults;
private Tab1FragmentListener tab1FragmentListener;
private String cityNameSearched;
public interface Tab1FragmentListener{
void onInput1Set(String input);
}
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container,
#Nullable Bundle savedInstanceState) {
View view=inflater.inflate(R.layout.tab1_frag, container, false);
getWeatherButton=(Button)view.findViewById(R.id.getWeatherButton);
searchCityByName=(EditText)view.findViewById(R.id.searchCityByName);
weatherResultTextView=(TextView)view.findViewById(R.id.weatherResult);
mainActivity=new MainActivity();
getWeatherButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
downloadTask=new DownloadTask(new DownloadTask.AsyncResponse() {
#Override
public void processFinish(String output) {
if(!output.equals("")){
weatherResultTextView.setText(output);
}else{
weatherResultTextView.setText("");
}
}
});
cityNameSearched=searchCityByName.getText().toString().trim();
tab1FragmentListener.onInput1Set(cityNameSearched);
Log.i("CityNameSearched", cityNameSearched);
try {
String encodedCityName= URLEncoder.encode(cityNameSearched,"UTF-8" );
} catch (Exception e) {
e.printStackTrace();
}
downloadTask.execute("https://openweathermap.org/data/2.5/weather?q="+cityNameSearched+"&appid=b6907d289e10d714a6e88b30761fae22");
Log.i("Button Cliked","Clicked");
InputMethodManager mgr=(InputMethodManager) getActivity().getSystemService(Context.INPUT_METHOD_SERVICE);
mgr.hideSoftInputFromWindow(searchCityByName.getWindowToken(), 0);
}
});
return view;
}
#Override
public void onAttach(Context context) {
super.onAttach(context);
if(context instanceof Tab1FragmentListener){
tab1FragmentListener=(Tab1FragmentListener)context;
}else{
throw new RuntimeException(context.toString()+
" must implement Tab1FragmentListener"
);
}
}
#Override
public void onDetach() {
super.onDetach();
tab1FragmentListener=null;
}
public void updateEditText(String newText){
searchCityByName.setText(newText);
}
}
public class MainActivity extends AppCompatActivity implements Tab1Fragment.Tab1FragmentListener {
private static final String TAG="MainActivity";
private SectionsPageAdapter mySectionPageAdapter;
private ViewPager viewPager;
private DataForTabs dataForTabs;
private Tab1Fragment tab1Fragment;
private Tab2Fragment tab2Fragment;
String input="";
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Log.d(TAG,"onCreate: Starting.");
tab1Fragment=new Tab1Fragment();
Log.i(" From 1 to main ", input);//No Log appears for this input variable
mySectionPageAdapter=new SectionsPageAdapter(getSupportFragmentManager());
//set up the ViewPager with the sections adaptor
viewPager=(ViewPager)findViewById(R.id.container);
setupViewPager(viewPager);
TabLayout tabLayout=(TabLayout)findViewById(R.id.tabs);
tabLayout.setupWithViewPager(viewPager);
}
public void setupViewPager(ViewPager viewPager){
SectionsPageAdapter adapter=new
SectionsPageAdapter(getSupportFragmentManager());
adapter.addFragment(new Tab1Fragment(),"Home");
adapter.addFragment(new Tab2Fragment(),"History");
adapter.addFragment(new Tab3Fragment(),"About");
viewPager.setAdapter(adapter);
}
#Override
public void onInput1Set(String input) {
tab2Fragment.updateEditText(input);
this.input=input;
}
}

Related

Fragment "overwrites" another fragment when first selected

I have Bottom Navigation with which I switch between 3 fragments: "ConnectFragment", "DashboardFragment" and "ChatFragment".
Switching from Connect to Chat and vice versa works OK, but when I select Dashboard it causes a bug that makes Dashboard appear when selecting Chat in navigation, what is causing this?
All 3 fragments have identical functionality and layout, so i assume the problem lays in MainActivity.
MainActivity:
public class MainActivity extends AppCompatActivity implements DashboardFragment.FragmentDashListener, ChatFragment.FragmentChatListener, ConnectFragment.FragmentConnListener {
FragmentManager fm = getSupportFragmentManager();
Fragment active;
Fragment FragmentConnect = new ConnectFragment();
Fragment FragmentDashboard = new DashboardFragment();
Fragment FragmentChat = new ChatFragment();
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
BottomNavigationView bottomNav = findViewById(R.id.bottom_navigation);
bottomNav.setOnNavigationItemSelectedListener(navListener);
fm.beginTransaction().add(R.id.fragment_container, FragmentChat).hide(FragmentChat).commit(); //Ustvari vse 3 fragmente, skrije 2 da se nena vedno znova kreirajo
fm.beginTransaction().add(R.id.fragment_container, FragmentDashboard).hide(FragmentDashboard).commit();
fm.beginTransaction().add(R.id.fragment_container, FragmentConnect).commit();
}
private BottomNavigationView.OnNavigationItemSelectedListener navListener = new BottomNavigationView.OnNavigationItemSelectedListener() {
#Override
public boolean onNavigationItemSelected(#NonNull MenuItem menuItem) {
active = FragmentConnect;
switch (menuItem.getItemId()) {
case R.id.nav_connect:
fm.beginTransaction().hide(active).show(FragmentConnect).commit();
active = FragmentConnect;
return true;
case R.id.nav_dashboard:
fm.beginTransaction().hide(active).show(FragmentDashboard).commit();
active = FragmentDashboard;
return true;
case R.id.nav_send:
fm.beginTransaction().hide(active).show(FragmentChat).commit();
active = FragmentChat;
return true;
}
return false;
}
};
#Override
public void onInputChatSent(CharSequence input) {
ConnectFragment.updateEditText(input);
}
#Override
public void onInputConnSent(CharSequence input) {
DashboardFragment.updateEditText(input);
}
#Override
public void onInputDashSent(CharSequence input) {
ChatFragment.updateEditText(input);
}
}
Fragments:
All 3 fragments have identical code, below are Dashboard and Chat.
public class DashboardFragment extends Fragment {
private FragmentDashListener listener;
private static EditText editText;
private Button ButtonOk;
public interface FragmentDashListener{
void onInputDashSent (CharSequence input);
}
#Nullable
#Override
public View onCreateView(#NonNull LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.fragment_dashboard, container, false);
editText = v.findViewById(R.id.edit_text);
ButtonOk = v.findViewById(R.id.Button_Ok);
ButtonOk.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
CharSequence input = editText.getText();
listener.onInputDashSent(input);
}
});
return v;
}
public static void updateEditText(CharSequence newText){
editText.setText(newText);
}
#Override
public void onAttach(Context context) {
super.onAttach(context);
if(context instanceof FragmentDashListener){
listener = (FragmentDashListener) context;
} else {
throw new RuntimeException(context.toString()+"must implement FragmentDashListener");
}
}
}
public class ChatFragment extends Fragment {
private FragmentChatListener listener;
private static EditText editText;
private Button ButtonOk;
public interface FragmentChatListener{
void onInputChatSent (CharSequence input);
}
#Nullable
#Override
public View onCreateView(#NonNull LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.fragment_chat, container, false);
editText = v.findViewById(R.id.edit_text);
ButtonOk = v.findViewById(R.id.Button_Ok);
ButtonOk.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
CharSequence input = editText.getText();
listener.onInputChatSent(input);
}
});
return v;
}
public static void updateEditText(CharSequence newText){
editText.setText(newText);
}
#Override
public void onAttach(Context context) {
super.onAttach(context);
if(context instanceof FragmentChatListener){
listener = (FragmentChatListener) context;
} else {
throw new RuntimeException(context.toString()+"must implement FragmentChatListener");
}
}
}

Remove the first line
active = FragmentConnect;
from onNavigationItemSelected method. This will fix the issue
or modify it as below
if(active == null) {
active = FragmentConnect;
}

Passing data from RecyclerView.Adapter to fragment onClick

I'm trying to figure out how to get data from a clicked item in a RecyclerView to a listview in a Fragment. I can't seem to figure out how to do this, as I can't get my bundle to work.
I've tried various solutions offered here on Stackoverflow, but none of them have worked. I have managed to get the info from the recyclerview, but I am stuck trying to figure out how I can pass it to the fragment. Can someone please help me?
The Adapter class:
public class FoodAdapter extends RecyclerView.Adapter<FoodAdapter.ViewHolder> {
private Context context;
ArrayList<FoodActivity> list;
public FoodAdapter(ArrayList<FoodActivity> list){
this.list = list;
}
#NonNull
#Override
public ViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.listview_item_food, parent, false);
return new ViewHolder(view);
}
#Override
public void onBindViewHolder(#NonNull final ViewHolder holder, final int position) {
holder.foods.setText(list.get(position).getName());
holder.carbo.setText(list.get(position).getCarbohydrates());
holder.protein.setText(list.get(position).getProtein());
holder.fats.setText(list.get(position).getFats());
//Get items from recyclerview when user clicks them. Then send them to FoodFragment
holder.itemView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
String foods = list.get(position).getName();
String carbo = list.get(position).getCarbohydrates();
String protein = list.get(position).getProtein();
String fats = list.get(position).getFats();
Toast.makeText(v.getContext(), "test: " + foods, Toast.LENGTH_SHORT).show();
}
});
}
#Override
public int getItemCount() {
return list.size();
}
class ViewHolder extends RecyclerView.ViewHolder {
TextView foods, carbo, fats, protein;
public ViewHolder(View itemView) {
super(itemView);
carbo = itemView.findViewById(R.id.carbo);
protein = itemView.findViewById(R.id.protein);
fats = itemView.findViewById(R.id.fats);
foods = itemView.findViewById(R.id.food);
}
}
}
The Fragment where the data comes from:
public class TrackingFragment extends Fragment {
DatabaseReference databaseReference;
ArrayList<FoodActivity> list;
RecyclerView recyclerView;
SearchView searchView;
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_tracking, container, false);
databaseReference = FirebaseDatabase.getInstance().getReference().child("foods");
recyclerView = view.findViewById(R.id.rv);
searchView = view.findViewById(R.id.searchFood);
return view;
}
#Override
public void onStart() {
super.onStart();
if(databaseReference != null){
databaseReference.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
if(dataSnapshot.exists()){
list = new ArrayList<>();
for(DataSnapshot ds : dataSnapshot.getChildren()){
list.add(ds.getValue(FoodActivity.class));
}
FoodAdapter adapter = new FoodAdapter(list);
recyclerView.setAdapter(adapter);
}
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
Toast.makeText(getActivity(), databaseError.getMessage(), Toast.LENGTH_SHORT).show();
}
});
}
if(searchView != null){
searchView.setOnQueryTextListener(new SearchView.OnQueryTextListener() {
#Override
public boolean onQueryTextSubmit(String query) {
return false;
}
#Override
public boolean onQueryTextChange(String newText) {
search(newText);
return true;
}
});
}
}
private void search(String str){
ArrayList<FoodActivity> searchList = new ArrayList<>();
for(FoodActivity object : list){
if(object.getName().toLowerCase().contains(str.toLowerCase())){
searchList.add(object);
}
}
FoodAdapter foodAdapter = new FoodAdapter(searchList);
recyclerView.setAdapter(foodAdapter);
}
}
And the class where it needs to go:
public class FoodFragment extends Fragment {
ImageButton addFood;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_food, container, false);
addFood = view.findViewById(R.id.addFood);
addFood.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
FragmentTransaction fr = getFragmentManager().beginTransaction();
fr.replace(R.id.fragment_container, new TrackingFragment());
fr.addToBackStack(null).commit();
}
});
return view;
}
}

The most simple is to add variables you need to your activity, set their values with onClick() and then retrieve data in other fragment:
in activity:
String foods;
public String getFoods() {
return foods;
}
public void setFoods(String foods) {
this.foods = foods;
}
in adapter:
holder.itemView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
((YourActivity)getActivity()).setFoods("Any value");
}
});
in destination fragment:
String foods = ((YourActivity)getActivity()).getFoods();

Add an interface to your adapter as follow
public class FoodAdapter extends RecyclerView.Adapter<FoodAdapter.ViewHolder> {
interface OnClickListener {
void onClick(FoodActivity clickedItem);
}
private OnClickListener mCallback;
private ArrayList<FoodActivity> list;
public FoodAdapter(ArrayList<FoodActivity> list){
this.list = list;
}
public void setOnClickListener(OnClickListener callback) {
mCallback = callback;
}
#NonNull
#Override
public ViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.listview_item_food, parent, false);
return new ViewHolder(view);
}
#Override
public void onBindViewHolder(#NonNull final ViewHolder holder, final int position) {
holder.foods.setText(list.get(position).getName());
holder.carbo.setText(list.get(position).getCarbohydrates());
holder.protein.setText(list.get(position).getProtein());
holder.fats.setText(list.get(position).getFats());
//Get items from recyclerview when user clicks them. Then send them to FoodFragment
holder.itemView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (mCallback != null)
mCallback.onClick(list.get(position));
}
});
}
#Override
public int getItemCount() {
return list.size();
}
class ViewHolder extends RecyclerView.ViewHolder {
TextView foods, carbo, fats, protein;
public ViewHolder(View itemView) {
super(itemView);
carbo = itemView.findViewById(R.id.carbo);
protein = itemView.findViewById(R.id.protein);
fats = itemView.findViewById(R.id.fats);
foods = itemView.findViewById(R.id.food);
}
}
}

Android sometimes is a little complicated, when it involves the full stack:
01 RecyclerView Adapter
/** 01. Some Adapter */
public class SomeAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
private WeakReference<Context> mContext;
/** Constructor */
public SomeAdapter(#NonNull Context context) {
this.mContext = new WeakReference<>(context);
}
#NonNull
protected Context getContext() {
return this.mContext.get();
}
/** Call to Activity from within the adapter. */
private void someMethod() {
SomeActivity activity = (SomeActivity) getContext();
synchronized(activity) {activity.showLoginDialog();}
}
}
02 AppCompatActivity
/** 02. Some Activity */
public class SomeActivity extends AppCompatActivity {
#Nullable
private BaseFragment currentFragment = null;
/** Constructor */
public SomeActivity() {}
public void setCurrentFragment(Fragment fragment) {
this.currentFragment = fragment;
}
/** Call to the current Fragment. */
public void someMethod() {
if (currentFragment != null) {
currentFragment.someMethod();
}
}
}
03 Fragment
/** Some Fragment */
public class SomeFragment extends Fragment {
/** Constructor */
public SomeFragment() {}
#Override
public void onAttach(#NonNull Context context) {
super.onAttach(context);
((BaseActivity) context).setCurrentFragment(this);
}
#Override
public void onDetach() {
super.onDetach();
((BaseActivity) getActivity()).setCurrentFragment(this);
}
}

To get your data from FoodAdapter to TrackingFragment, you can add TrackingFragment (or an interface it implements, ideally) as a parameter to the FoodAdapter constructor, then use that instance to forward your ViewHolder clicks to TrackingFragment for handling.
To get your data from TrackingFragment to FoodFragment, use the setTargetFragment/onActivityResult pattern for fragment <-> fragment communication. This answer has an example: https://stackoverflow.com/a/13733914/3238938

ArrayList not displaying in RecyclerView but no errors shown

I've have an arraylist that is not displaying in RecyclerView. The arraylist has data but my RecyclerView Adapter shows no error, nor is my fragment activity showing no errors. I am at a complete loss where the programming error is. The getItemCount seems correct, the holder seems correct and the Fragment seems to be correct but I know there is a mistake somewhere. Here is my code:
Fragment:
public class TestFragment extends Fragment {
private static final String ARG_PARAM1 = "param1";
private static final String ARG_PARAM2 = "param2";
List<PlanetData> items = new ArrayList<>();
RecyclerView mRecyclerView;
PlanetRecyclerViewAdapter adapter;
private OnFragmentInteractionListener mListener;
public TestFragment() {
// Required empty public constructor
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setHasOptionsMenu(true);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState) {
planetList();
// Inflate the layout for this fragment
View view = inflater.inflate(R.layout.fragment_test, container, false);
mRecyclerView = (RecyclerView)view.findViewById(R.id.planet_recycler_view);
mRecyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
mRecyclerView.addItemDecoration(new DividerItemDecoration(mRecyclerView.getContext(),DividerItemDecoration.VERTICAL));
adapter = new PlanetRecyclerViewAdapter(items, mRecyclerView.getContext());
mRecyclerView.setAdapter(adapter);
return view;
}
// TODO: Rename method, update argument and hook method into UI event
public void onButtonPressed(Uri uri) {
if (mListener != null) {
mListener.onFragmentInteraction(uri);
}
}
#Override
public void onAttach(Context context) {
super.onAttach(context);
if (context instanceof OnFragmentInteractionListener) {
mListener = (OnFragmentInteractionListener) context;
} else {
throw new RuntimeException(context.toString()
+ " must implement OnFragmentInteractionListener");
}
}
#Override
public void onDetach() {
super.onDetach();
mListener = null;
}
public interface OnFragmentInteractionListener {
// TODO: Update argument type and name
void onFragmentInteraction(Uri uri);
}
private List<PlanetData> planetList() {
List<PlanetData> planetvalues = new ArrayList<>();
planetvalues.add(new com.ksburneytwo.planetmathtest.PlanetData("12"));
planetvalues.add(new com.ksburneytwo.planetmathtest.PlanetData(Double.toString(Mercury.getMercuryRA())));
planetvalues.add(new com.ksburneytwo.planetmathtest.PlanetData(Double.toString(Venus.getVenusRA())));
planetvalues.add(new com.ksburneytwo.planetmathtest.PlanetData(Double.toString(Moon.getMoonRA())));
planetvalues.add(new com.ksburneytwo.planetmathtest.PlanetData(Double.toString(Mars.getMarsRA())));
planetvalues.add(new com.ksburneytwo.planetmathtest.PlanetData(Double.toString(Jupiter.getJupiterRA())));
planetvalues.add(new com.ksburneytwo.planetmathtest.PlanetData(Double.toString(Saturn.getSaturnRA())));
planetvalues.add(new com.ksburneytwo.planetmathtest.PlanetData(Double.toString(Uranus.getUranusRA())));
planetvalues.add(new com.ksburneytwo.planetmathtest.PlanetData(Double.toString(Neptune.getNeptuneRA())));
planetvalues.add(new com.ksburneytwo.planetmathtest.PlanetData(Double.toString(Pluto.getPlutoRA())));
System.out.println("This is Arraylist:" + planetvalues);
return planetvalues;
}
}
Here is the PlanetData class:
public class PlanetData {
private String PlanetRA;
public PlanetData(String PlanetRA) {
this.PlanetRA = PlanetRA;
}
#Override
public String toString() {
return PlanetRA;
}
public String getPlanetRA (){
return PlanetRA;
}
public void setPlanetRA(String PlanetRA){
this.PlanetRA = PlanetRA;
}
}
Here is my RecyclerView Adapter:
public class PlanetRecyclerViewAdapter extends RecyclerView.Adapter<PlanetRecyclerViewAdapter.ViewHolder> {
private List<PlanetData> mPlanetDataList;
Context mContext;
public static class ViewHolder extends RecyclerView.ViewHolder{
public TextView currentRA;
public ViewHolder(View itemView) {
super(itemView);
currentRA = (TextView) itemView.findViewById(R.id.planet_location);
}
}
public PlanetRecyclerViewAdapter(List<PlanetData> mPlanetDataList, Context mContext){
this.mPlanetDataList = mPlanetDataList;
this.mContext = mContext;
}
#Override
public PlanetRecyclerViewAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View itemView = LayoutInflater.from(parent.getContext()).inflate(R.layout.planet_recycler_item,parent, false);
return new ViewHolder(itemView);
}
#Override
public void onBindViewHolder( PlanetRecyclerViewAdapter.ViewHolder holder, int position) {
holder.currentRA.setText(mPlanetDataList.get(position).getPlanetRA());
}
#Override
public int getItemCount() {
return mPlanetDataList.size();
}
}

I don't see you ever actually adding anything to the items list.
You call planetList() in onCreateView(), but you aren't using the result of it, and planetList() doesn't affect items in any way: it makes its own ArrayList and returns that.
Either remove planetValues from the planetList() method and reference items directly:
private void planetList() { //changed signature to "void"
items.add(...);
items.add(...);
//etc
}
Or set the result of planetList() to items when you call it:
items.addAll(planetList());

You haven't populated items.
items = planetList();

ViewPager setCurrentItem(position) not working after orientation change

i'm facing an issue i can't seem to resolve and i'd like some help.
My app is composed by an activity containing a fragment. After the user taps on a suggestion, activity's method onSuggestionClicked(String cardId) is called and activity's content is replaced with a new PagerFragment_new.
#Override
public void onSuggestionClicked(String cardId) {
Log.d("activity","ID:\t" + cardId);
PagerFragment_new pagerFragment = PagerFragment_new.getInstance(
Injection.provideMtgDatabase(getApplicationContext()),
activityPresenter.getAllCardExpansionIds(cardId),
this);
ActivityUtils.replaceFragment(getSupportFragmentManager(), pagerFragment, R.id.MTGRecallActivity_container);
}
PagerFragment_new contains a ViewPager to display CardInfoFragment_new
public class PagerFragment_new extends MtgRecallFragment_new implements PagerFragmentContract.View {
private View fragmentView;
private ViewPager viewPager;
private PagerFragmentContract.Presenter presenter;
private ScreenSlidePageAdapter_new adapter;
private MtgDatabase database;
private String[] printingsIds;
private ScreenSlidePageAdapter_new.ActivePresenterListener listener;
public PagerFragment_new() {
//Required empty constructor
}
public static PagerFragment_new getInstance(MtgDatabase database, String[] printingsIds, ScreenSlidePageAdapter_new.ActivePresenterListener listener) {
PagerFragment_new instance = new PagerFragment_new();
instance.setDatabase(database);
instance.setPrintingsIds(printingsIds);
instance.listener = listener;
return instance;
}
//other stuff
#Override
public void onCreate(#Nullable Bundle savedInstanceState) {
setRetainInstance(true);
super.onCreate(savedInstanceState);
}
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
setHasOptionsMenu(true);
fragmentView = inflater.inflate(R.layout.fragment_pager, container, false);
viewPager = (ViewPager) fragmentView.findViewById(R.id.PAGERFRAG_VIEWPAGER);
adapter = new ScreenSlidePageAdapter_new(getChildFragmentManager(), printingsIds, database, viewPager);
adapter.setListener(listener);
viewPager.setAdapter(adapter);
viewPager.setOffscreenPageLimit(1);
return fragmentView;
}
#Override
public void setPresenter(PagerFragmentContract.Presenter presenter) {
this.presenter = presenter;
}
}
The adapter to manage ViewPager's element's is ScreenSlidePageAdapter_new, it is responsible of instantiating CardInfoFragments.
public class ScreenSlidePageAdapter_new extends FragmentStatePagerAdapter {
private String[] printingsIds;
private String firstItemId;
private MtgDatabase database;
public ActivePresenterListener activity;
private ViewPager viewPager;
public ScreenSlidePageAdapter_new(FragmentManager fm, String[] printingsIds, MtgDatabase database, ViewPager viewPager) {
super(fm);
this.printingsIds =printingsIds;
this.database = database;
this.firstItemId = printingsIds[0];
this.viewPager = viewPager;
}
#Override
public Fragment getItem(int position) {
//todo create a bundle with cardId
Bundle bundle = new Bundle();
bundle.putString("CardID", printingsIds[position]);
bundle.putString("FirstItemId", firstItemId);
CardInfoFragment_new cardInfoFragment_new = CardInfoFragment_new.getInstance(viewPager);
cardInfoFragment_new.setArguments(bundle);
CardInfoPresenter cardInfoPresenter = new CardInfoPresenter(cardInfoFragment_new, database);
activity.setActivePresenter(cardInfoPresenter);
return cardInfoFragment_new;
}
#Override
public void destroyItem(ViewGroup container, int position, Object object) {
super.destroyItem(container, position, object);
}
public void setListener(ActivePresenterListener listener) {
this.activity = listener;
}
#Override
public int getCount() {
return printingsIds.length;
}
public interface ActivePresenterListener {
void setActivePresenter(BasePresenter presenter);
}}
Finally, here's the code of CardInfoFragment:
public class CardInfoFragment_new extends MtgRecallFragment_new
implements CardInfoContract.View,
CardPrintingsAdapter.OnItemClickListener {
private ViewPager viewPager;
public CardInfoContract.Presenter presenter;
private View fragmentView;
private MTGCard mtgCard;
RecyclerView printingsRecyclerView;
CardPrintingsAdapter cardPrintingsAdapter;
private String firstItemId; //the first id
public CardInfoFragment_new() {
//required empty constructor
}
private void setViewPager(ViewPager viewPager) {
this.viewPager = viewPager;
}
public static CardInfoFragment_new getInstance(ViewPager viewPager) {
CardInfoFragment_new cardInfoFragment_new = new CardInfoFragment_new();
cardInfoFragment_new.setViewPager(viewPager);
return cardInfoFragment_new;
}
#Override
public void onCreate(#Nullable Bundle savedInstanceState) {
setRetainInstance(true);
presenter.start();
String cardId = getArguments().getString("CardID");
firstItemId = getArguments().getString("FirstItemId");
mtgCard = presenter.getCardData(cardId);
super.onCreate(savedInstanceState);
}
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
fragmentView = inflater.inflate(R.layout.fragment_card_info_new, container, false);
setUpCardInfoView(fragmentView);
return fragmentView;
}
public void setUpCardInfoView(final View view){
//others view set-up action omitted
cardprintingsContainer = (LinearLayout) view.findViewById(R.id.CARDINFO_printingsContainer);
printingsRecyclerView = (RecyclerView)fragmentView.findViewById(R.id.CARDINFO_printings_recyclerView);
final List<String> printings = presenter.getCardPrintings(firstItemId, mtgCard.getName());
if (printings.size() < 40) {
setupPrintings(printings,printingsRecyclerView);
}
else {
LayoutInflater inflater = (LayoutInflater) getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
LinearLayout printingsRow = new LinearLayout(getContext());
printingsRow = (LinearLayout)inflater.inflate(R.layout.card_info_printings_row,printingsRow,true);
printingsRow.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
setupPrintings(printings, printingsRecyclerView);
}
});
ImageView printingssetImage = (ImageView)printingsRow.findViewById(R.id.CARDINFO_printingsRow_setImage);
printingssetImage.setVisibility(View.INVISIBLE);
TextView printingssetName = (TextView)printingsRow.findViewById(R.id.CARDINFO_printingsRow_setName);
printingssetName.setText("Click to see all the "+printings.size()+ " versions");
cardprintingsContainer.addView(printingsRow);
}
}
public void setupPrintings(List<String> printings, RecyclerView recyclerView) {
cardPrintingsAdapter =
new CardPrintingsAdapter(getContext(), printings);
cardPrintingsAdapter.setOnItemClickListener(this);
UnscrollableLayoutManager layoutManager = new UnscrollableLayoutManager(getContext(), LinearLayoutManager.VERTICAL, false);
recyclerView.setAdapter(cardPrintingsAdapter);
recyclerView.setLayoutManager(layoutManager);
}
#Override
public void onItemClick(View itemView, int position) {
int i = viewPager.getAdapter().getCount();
viewPager.setCurrentItem(position);
}
#Override
public void onDestroy() {
presenter = null;
mtgCard = null;
super.onDestroy();
}}
When user click on a RecyclerView item, CardInfoFragment's method onItemClick(View itemView, int position) is called and the viewpager is set to current position. Everything as expected.
THE PROBLEM
When the orientation changes, fragments are able to retain their states, but viewPager.setCurrentItem(position) does nothing, and i'm not able to change displayed fragment.
I already checked:
ViewPager instance and adapters instances corresponds to those passed to Fragments
onItemClick is fired
this questions question1 question2
If i use
android:configChanges="orientation|screenSize"
in manifest it works even after config changes, but i don't want to use this option since is discouraged.
Thanks in advance!

By default, when certain key configuration changes happen on Android (a common example is an orientation change), Android fully restarts the running Activity to help it adjust to such changes.
When you define android:configChanges="keyboardHidden|orientation" in your AndroidManifest, you are telling Android: "Please don't do the default reset when the keyboard is pulled out, or the phone is rotated; I want to handle this myself. Yes, I know what I'm doing".
So use configChanges.
The use of this is discouraged, IF you don't know how to use it. But for a case like this, I would suggest you use it. IF not, still the activity will be recreated. which just takes time, resources, and I don't see why you would want that to happen.

FragmentTabHost with own fragment stack for each tab

I have MainActivity which has FragmentTabHost with several tabs. Each fragment in tab can be replaced with another fragment, so if we navigate back, we will see first displayed fragment for this tab (own stack for each tab). I have a quite working solution.
The below example demonstrates TabHost with 2 tabs and fragment classes for the first tab.
Is there any simpler, better or more elegant way to achieve this result?
AbstractPrimaryFragment.java. This class is a root fragment class that replaces fragments inside it. Other tab fragment classes can extend this superclass.
public abstract class AbstractPrimaryFragment extends Fragment {
// Simple framelayout.
private static final int RES_ID = R.layout.primary_fragment_layout;
protected static final int CONTENT_LAYOUT_ID = R.id.primary_fragment_layout;
protected Fragment mActiveFragment;
public AbstractPrimaryFragment()
{
setRetainInstance(true);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
return inflater.inflate(RES_ID, container, false);
}
#Override
public void onActivityCreated(Bundle savedInstanceState)
{
super.onActivityCreated(savedInstanceState);
// Check if active fragment is in layout, if not, make default fragment for this tab.
mActiveFragment = getChildFragmentManager().findFragmentById(CONTENT_LAYOUT_ID);
if (mActiveFragment == null)
{
mActiveFragment = makeDefaultActiveFragment();
String tag = getDefaultFragmentTag();
getChildFragmentManager().beginTransaction().add(CONTENT_LAYOUT_ID, mActiveFragment, tag).commit();
}
}
public boolean onBackPressed()
{
boolean backPressed = false;
final FragmentManager fragmentManager = getChildFragmentManager();
if (fragmentManager.getBackStackEntryCount() > 0)
{
fragmentManager.addOnBackStackChangedListener(new OnBackStackChangedListener()
{
#Override
public void onBackStackChanged()
{
mActiveFragment = fragmentManager.findFragmentById(CONTENT_LAYOUT_ID);
fragmentManager.removeOnBackStackChangedListener(this);
}
});
fragmentManager.popBackStack();
backPressed = true;
}
return backPressed;
}
protected abstract Fragment makeDefaultActiveFragment();
protected abstract String getDefaultFragmentTag(); }
Tab1PrimaryFragment.java
public class Tab1PrimaryFragment extends AbstractPrimaryFragment implements OnTab1Fragment1Listener {
private static final String FRAGMENT1_TAG = "tab1_fragment1";
private static final String FRAGMENT2_TAG = "tab2_fragment2";
#Override
protected Fragment makeDefaultActiveFragment()
{
return new Tab1Fragment1();
}
#Override
protected String getDefaultFragmentTag()
{
return FRAGMENT1_TAG;
}
#Override
public void onTab1Fragment1ButtonClick(Tab1Fragment1 tab1Fragment1)
{
Tab1Fragment2 tab1Fragment2 = new Tab1Fragment2();
getChildFragmentManager().beginTransaction().replace(CONTENT_LAYOUT_ID, tab1Fragment2, FRAGMENT2_TAG).addToBackStack(tab1Fragment1.getTag()).commit();
mActiveFragment = tab1Fragment2;
}}
Tab1Fragment1.class (default active fragment)
public class Tab1Fragment1 extends Fragment {
public interface OnTab1Fragment1Listener
{
public void onTab1Fragment1ButtonClick(Tab1Fragment1 tab1Fragment1);
}
private OnTab1Fragment1Listener mOnTab1Fragment1Listener;
public void setOnTab1Fragment1Listener(OnTab1Fragment1Listener onTab1Fragment1Listener)
{
mOnTab1Fragment1Listener = onTab1Fragment1Listener;
}
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
Fragment parentFragment = getParentFragment();
if (parentFragment != null && parentFragment instanceof OnTab1Fragment1Listener)
{
mOnTab1Fragment1Listener = (OnTab1Fragment1Listener) parentFragment;
}
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
Button button = new Button(getActivity());
button.setOnClickListener(new OnClickListener()
{
#Override
public void onClick(View v)
{
if(mOnTab1Fragment1Listener != null)
{
mOnTab1Fragment1Listener.onTab1Fragment1ButtonClick(Tab1Fragment1.this);
}
}
});
return button; }}
Tab1Fragment2.java. Dummy fragment. This fragment is displayed when onTab1Fragment1ButtonClick is called.
public class Tab1Fragment2 extends Fragment {}
And MainActivity.java
public class MainActivity extends FragmentActivity {
private static final int RES_ID = R.layout.main_activity;
private static final int TAB_CONTENT_ID = android.R.id.tabcontent;
private static final int TABHOST_ID = android.R.id.tabhost;
private static final String TAB1_PRIMARY_FRAGMENT_TAG = "tab1_primary_fragment";
private static final String TAB2_PRIMARY_FRAGMENT_TAG = "tab2_primary_fragment"
private FragmentTabHost mTabHost;
#Override
protected void onCreate(Bundle bundle)
{
super.onCreate(bundle);
setContentView(RES_ID);
initializeTabHost();
}
private void initializeTabHost()
{
mTabHost = (FragmentTabHost) findViewById(TABHOST_ID);
mTabHost.setup(this, getSupportFragmentManager(), TAB_CONTENT_ID);
LayoutInflater inflater = LayoutInflater.from(this);
mTabHost.addTab(mTabHost.newTabSpec(TAB1_PRIMARY_FRAGMENT_TAG).setIndicator(inflater.inflate(R.layout.smth1, null)), Tab1PrimaryFragment.class, null);
mTabHost.addTab(mTabHost.newTabSpec(TAB2_PRIMARY_FRAGMENT_TAG).setIndicator(inflater.inflate(R.layout.smth2, null)), Tab2PrimaryFragment.class, null);
}
#Override
public void onBackPressed()
{
Fragment fragment = getSupportFragmentManager().findFragmentById(TAB_CONTENT_ID);
if (fragment != null && fragment instanceof AbstractPrimaryFragment)
{
if (((AbstractPrimaryFragment) fragment).onBackPressed())
{
return;
}
}
super.onBackPressed();
}}

Develop Reference

Java is a programming language and computing platform first released by Sun Microsystems in 1995.

Where to define Async class in a multi tab android project - java

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FragmentTabHost with own fragment stack for each tab

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