Develop Reference

Android app - Google maps location markers disappearing from Map fragment

I am very new to Android development. This is my first attempt at creating an app. I have created a tabbed navigation app, with 4 fragments to navigate between: Home, Search, Map and Account fragments from the MainActivity. I have used a SupportMapFragment within my MapsFragment to display the map. Upon visiting the MapsFragment the map displays and zooms in on my Current location and highlights certain important locations, retrieved from a Firebase instance, with markers.
Everything works as expected when I first launch the app and visit the Map Fragment. I am zoomed into my current location and I see all required markers. The problem arises when I switch to a different fragment from that point. When I navigate to the Home, Search or Account fragment and then return to the Map fragment, none of the location markers are visible anymore. I can still see my current location and get zoomed into it on opening the Map fragment but the other markers disappear.
I originally thought it was to do with the fragment being recreated everytime I navigate to another fragment as I use .replace(container, fragment) to change the fragment based on which button was clicked from the bottom navigation bar. But I observed that the Map fragment would load my current location and zoom into it correctly, so the loadMap() function gets executed but somehow the markers don't appear. If i restart the app, the markers behave correctly the first time I open the Map fragment.
Any help on how to keep the markers showing on the Map when I return to it after navigating to other fragments will be greatly appreciated. Thank you!
Here is a preview of my MapsFragment.java:
public class MapsFragment extends Fragment {
private SupportMapFragment supportMapFragment;
private AutocompleteSupportFragment autocompleteSupportFragment;
private FusedLocationProviderClient client;
private Geocoder geocoder;
private ArrayList<String> mPostCodes;
private ArrayList<Marker> searchMarker;
private DatabaseReference locationRef;
private DatabaseReference businessRef;
private String apiKey;
public MapsFragment() {
// Required empty public constructor
}
#Override
public void onViewCreated(#NonNull View view, #Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
// Initialize Map fragment
supportMapFragment = (SupportMapFragment)
getChildFragmentManager().findFragmentById(R.id.google_map);
// initialize Places client
apiKey = getString(R.string.map_key);
if(!Places.isInitialized()){
Places.initialize(requireActivity(), apiKey);
}
PlacesClient placesClient = Places.createClient(requireActivity());
// Initialize AutoComplete search bar and set autocomplete parameters
autocompleteSupportFragment = (AutocompleteSupportFragment)
getChildFragmentManager().findFragmentById(R.id.autocomplete_fragment);
autocompleteSupportFragment.setTypeFilter(TypeFilter.ADDRESS);
autocompleteSupportFragment.setLocationBias(RectangularBounds.newInstance(
new LatLng(55.836229, -4.252612),
new LatLng(55.897463, -4.325364)));
autocompleteSupportFragment.setCountries("UK");
autocompleteSupportFragment.setPlaceFields(Arrays.asList(Place.Field.ID, Place.Field.NAME, Place.Field.LAT_LNG));
// initialize search marker list
searchMarker = new ArrayList<Marker>();
// Initialize client to get user's last location on device
client = LocationServices.getFusedLocationProviderClient(requireActivity());
// Initialize geocoder to convert business postcodes to latlng coordinates
mPostCodes = new ArrayList<>();
geocoder = new Geocoder(requireActivity());
// Get business locations
locationRef = FirebaseDatabase.getInstance().getReference("Business Locations");
locationRef.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot snapshot) {
if(snapshot.exists()){
for(DataSnapshot locationSnapshot : snapshot.getChildren()){
BusinessLocation location = locationSnapshot.getValue(BusinessLocation.class);
mPostCodes.add(location.getPostCode());
}
}
}
#Override
public void onCancelled(#NonNull DatabaseError error) {
Log.i("Location error", "Error retrieving location: ", error.toException().getCause());
}
});
// initialize reference to business table
businessRef = FirebaseDatabase.getInstance().getReference("Businesses");
// render the map
loadMap();
}
private void loadMap() {
if (ActivityCompat.checkSelfPermission(requireActivity(),
Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED) {
Task<Location> task = client.getLastLocation();
task.addOnSuccessListener(new OnSuccessListener<Location>() {
#Override
public void onSuccess(Location location) {
if(location != null){
supportMapFragment.getMapAsync(new OnMapReadyCallback() {
#Override
public void onMapReady(#NonNull GoogleMap googleMap) {
// autocomplete place search
autocompleteSupportFragment.setOnPlaceSelectedListener(new PlaceSelectionListener() {
#Override
public void onError(#NonNull Status status) {
Log.i("AutoComplete error", "error status: " + status);
}
#Override
public void onPlaceSelected(#NonNull Place place) {
LatLng placeLatLng = place.getLatLng();
MarkerOptions placeOptions = new MarkerOptions().position(placeLatLng)
.title("search")
.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_AZURE));
if(!searchMarker.isEmpty()){
Marker searchedMarker = searchMarker.get(0);
searchMarker.remove(searchedMarker);
searchedMarker.remove();
}
final Marker marker = googleMap.addMarker(placeOptions);
searchMarker.add(marker);
googleMap.animateCamera(CameraUpdateFactory.newLatLngZoom(placeLatLng, 10));
}
});
LatLng myLatLng = new LatLng(location.getLatitude(),
location.getLongitude());
// show current location
if (ActivityCompat.checkSelfPermission(requireActivity(),
Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED) {
googleMap.setMyLocationEnabled(true);
googleMap.getUiSettings().setZoomControlsEnabled(true);
googleMap.getUiSettings().setCompassEnabled(true);
}
// show markers for all businesses on database
for(String code : mPostCodes){
try{
Address address = geocoder.getFromLocationName(code, 1).get(0);
LatLng latLng = new LatLng(address.getLatitude(), address.getLongitude());
MarkerOptions options = new MarkerOptions().position(latLng);
googleMap.addMarker(options);
}catch (IOException e){
Toast.makeText(requireActivity(), e.getMessage(), Toast.LENGTH_LONG).show();
}
}
googleMap.animateCamera(CameraUpdateFactory.newLatLngZoom(myLatLng, 10));
}
});
}
}
});
}else {
ActivityCompat.requestPermissions(requireActivity(),
new String[]{Manifest.permission.ACCESS_FINE_LOCATION}, 44);
}
}
private ActivityResultLauncher<String> mPermissionResult = registerForActivityResult(
new ActivityResultContracts.RequestPermission(),
result -> {
if(result){
loadMap();
}
}
);
}
Here is my fragment_maps.xml file:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:app="http://schemas.android.com/apk/res-auto"
tools:context=".fragments.MapsFragment">
<fragment
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="#+id/google_map"
android:name="com.google.android.gms.maps.SupportMapFragment"/>
<fragment
android:id="#+id/autocomplete_fragment"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:name="com.google.android.libraries.places.widget.AutocompleteSupportFragment"/>
</RelativeLayout>
And here is my MainActivity.kt file:
class MainActivity : AppCompatActivity() {
private val homeFragment = HomeFragment()
private val searchFragment = SearchFragment()
private val mapFragment = MapsFragment()
private val accountFragment = AccountFragment()
private val guestAccountFragment = GuestAccountFragment()
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
replaceFragment(homeFragment)
bottom_navigation.setOnItemSelectedListener {
when (it.itemId) {
R.id.id_home -> replaceFragment(homeFragment)
R.id.id_search -> replaceFragment(searchFragment)
R.id.id_map -> replaceFragment(mapFragment)
R.id.id_account -> {
if(FirebaseAuth.getInstance().currentUser == null){
replaceFragment(guestAccountFragment)
}else {
replaceFragment(accountFragment)
}
}
}
true
}
}
private fun replaceFragment(fragment : Fragment){
if(fragment != null){
val transaction = supportFragmentManager.beginTransaction()
transaction.replace(R.id.fragment_container, fragment)
transaction.commit()
}
}
}

It happening beacuse your map fragment is "dying" after replacing on new fragment. Try this solution:
First of all you need add in your main activity all required fragments which can be called:
getSupportFragmentManager().beginTransaction()
.add(R.id.fragment_container_view, fragment1)
.add(R.id.fragment_container_view, fragment2)
.add(R.id.fragment_container_view, fragment3)
.commit();
After adding you can change them by calling this code:
getSupportFragmentManager().beginTransaction()
.show(fragment2)
.hide(fragment1)
.commit();
Code was writen on Java but I think there is no problem

Past value from child fragment -> mainactivity cannot cast fragment_fr_event_Birthday to fragment_fr_event_wedding android studio

I have a Fragment inside the mainActivity, the fragment contains fragmentcontainerView which can be replaced by multiple child fragments with spinner onselectedListener. I want to able to pass those values from the child fragment via eg: Do something with: fragmentevent.TogetFName(); with a button in Mainactivity. In the parent fragment , I get the value from the child fragment(fragment_Birthday) with fragment_fr_event_birthday = (fragment_fr_event_Birthday) getChildFragmentManager().findFragmentById(R.id.fragment_event_child_fragment); and other value from other childfragment with frag_fr_event_wed = (fragment_fr_event_wedding) getChildFragmentManager().findFragmentById(R.id.fragment_event_child_fragment);, I know that they cannot be assigned with the different fragment class at once, but is there a clever way to do this or is there any other way I can pass value from child -> parent fragment->mainActivity
MainActivity:
public void onClick(View view){
case "Event":
Fragment_fr_Event fragment_fr_event = (Fragment_fr_Event) getSupportFragmentManager().findFragmentById(R.id.fragment_generated_mainView);
if(fragment_fr_event.TogetWedChildFcoupleName() !=null && fragment_fr_event.TogetEventType().equals("Wedding")){
testThis.setText(fragment_fr_event.TogetWedChildFcoupleName());
}if( fragment_fr_event.TogetEventType().equals("Birthday") && fragment_fr_event.TogetBirthdayFName() !=null){
testTat.setText(fragment_fr_event.TogetBirthdayFName());
}
}
ChildFragment(BirthdayFragment):
public String TogetEventBirthdayFName (){
EditText FBirthdayName = rootView.findViewById(R.id.Edittext_birthDay_FirstName);
return FBirthdayName.getText().toString();
}
ChildFragment(Wedding fragment):
public String toGetFcoupleName(){
EditText FCoupleName = rootView.findViewById(R.id.textView_wedding_Name);
return FCoupleName.getText().toString();
}
ParentFragment(EventFragment):
#Override
public void onViewCreated(#NonNull View view, #Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
Spinner TypeEventSpinner = rootview.findViewById(R.id.type_event);
TypeEventSpinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
#Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
String tag_items = parent.getItemAtPosition(position).toString();
switch (tag_items){
case "Wedding":
frag_fr_event_wed = new fragment_fr_event_wedding();
FragmentTransaction transaction = getChildFragmentManager().beginTransaction();
transaction.replace(R.id.fragment_event_child_fragment, frag_fr_event_wed).disallowAddToBackStack().commit();
break;
case "Birthday":
fragment_fr_event_birthday = new fragment_fr_event_Birthday();
transaction = getChildFragmentManager().beginTransaction();
transaction.replace(R.id.fragment_event_child_fragment , fragment_fr_event_birthday).disallowAddToBackStack().commit();
break;
}
}
#Override
public void onNothingSelected(AdapterView<?> parent) {
}
});
}
public String TogetWedChildFcoupleName(){
if(frag_fr_event_wed !=null){
frag_fr_event_wed = (fragment_fr_event_wedding) getChildFragmentManager().findFragmentById(R.id.fragment_event_child_fragment);
return frag_fr_event_wed.toGetFcoupleName();
}return "Empty";
}
public String TogetBirthdayFName(){
if(fragment_fr_event_birthday != null){
fragment_fr_event_birthday = (fragment_fr_event_Birthday) getChildFragmentManager().findFragmentById(R.id.fragment_event_child_fragment);
return fragment_fr_event_birthday.TogetEventBirthdayFName();
}
return "Empty";
}

To be honest , I couldn't understand what you did there , but i got what you want , you want to communicate with parent's parent class , the way you are doing it made it so complicated even it's not readable , BUT of course there are always a good way to do something , in your case there are Android Navigation Component , which give you the simplicity and power to do make it much more easy to handle , You can put all your fragment in one graph and from within the destinations "fragment are called destinations here" you can communicate with other fragment and the parent using actions and global actions "going from one fragment to another is called action here" parameters, but there are no need to a parent's parent here , all destinations and its parent can share one ViewModel which will allow you to share data all around your app .
You can read more if it sound good to you here

Fragment in activity startup taking more time than expected

I am a beginner-intermediate android developer. I started working with fragments in my this app. The structure of the app is:
Main activity where some important links are embedded with buttons
On clicking button from main activity, some DB tasks completed (with Room Library so all tasks are using AsyncTask) and new activity opens with link in intent extra
On getting the link, the new activity-2 adds a fragment (in itself) and also performs some DB tasks in background and then opens the link in webview of fragment.
The problem is, from 1-2 it is taking merely 0.1-0.15 seconds while on starting the task 3, it is taking 0.3-0.45 seconds so on clicking from main activity, user is getting the link opened in fragment (which has webview) in about 0.6 seconds which is making feel like app is freezing.
Here are some codes:
Activity-2:
#Override
protected void onCreate(Bundle savedInstanceState) {
prefSingleton = PrefSingleton.getInstance();
if (prefSingleton.getStorage().getBoolean(Constants.STORAGE_ENABLE_NIGHTMODE,false)){
setTheme(R.style.DarkTheme);
}
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_website_view);
Toolbar toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
getSupportActionBar().setDisplayShowTitleEnabled(false);
closeWebview = toolbar.findViewById(R.id.closeWebview);
downArrow = toolbar.findViewById(R.id.downArrow);
allTabs = toolbar.findViewById(R.id.allTabs);
searchIcon = toolbar.findViewById(R.id.search);
clearEditText = toolbar.findViewById(R.id.clearEditText);
selectedSEImage = toolbar.findViewById(R.id.selectedSEImage);
searchEditText = toolbar.findViewById(R.id.searchEditText);
searchEngineFrame = toolbar.findViewById(R.id.searchEngine);
searchBarLayout = toolbar.findViewById(R.id.searchBarLayout);
toolbarTitle = toolbar.findViewById(R.id.toolBarTitle);
navFrame = findViewById(R.id.navFrame);
navRecView = findViewById(R.id.navRecView);
if (prefSingleton.getStorage().getBoolean(Constants.STORAGE_ENABLE_NIGHTMODE,false)){
navFrame.setBackgroundColor(getResources().getColor(R.color.night_mode_toolbar));
}
//Activity toolbar views
closeWebview.setOnClickListener(this);
closeWebview.setOnLongClickListener(this);
downArrow.setOnClickListener(this);
allTabs.setOnClickListener(this);
searchIcon.setOnClickListener(this);
clearEditText.setOnClickListener(this);
searchEngineFrame.setOnClickListener(this);
searchEditText.setOnClickListener(this);
searchEditText.setOnKeyListener(this);
//Intent from main activity
Intent i = getIntent();
String urlType = i.getStringExtra(String.valueOf(EnumVal.SiteInfoToSend.TYPE));
final String url = i.getStringExtra(String.valueOf(EnumVal.SiteInfoToSend.URL));
String title = i.getStringExtra(String.valueOf(EnumVal.SiteInfoToSend.TITLE));
String searchedText = i.getStringExtra(String.valueOf(EnumVal.SiteInfoToSend.SEARCHED_TEXT));
fragCounter = 0;
fragTags = new ArrayList<>();
//Fragment opening
if (savedInstanceState == null){
openFragment(url, EnumVal.FragStatus.NEW, null);
}
//AdMob Ads
if (!BuildConfig.PAID_VERSION){
mInterstitialAd = new InterstitialAd(this);
mInterstitialAd.setAdUnitId(getResources().getString(R.string.interstitial_webview));
mInterstitialAd.setAdListener(new AdListener() {
#Override
public void onAdFailedToLoad(int errorCode) {
if(ConsentInformation.getInstance(WebsiteView.this).getConsentStatus() ==
ConsentStatus.NON_PERSONALIZED){
Bundle extras = new Bundle();
extras.putString("npa", "1");
mInterstitialAd.loadAd(new AdRequest.Builder()
.addNetworkExtrasBundle(AdMobAdapter.class,extras).build());
} else {
mInterstitialAd.loadAd(new AdRequest.Builder().build());
}
}
});
if(ConsentInformation.getInstance(WebsiteView.this).getConsentStatus() == ConsentStatus.NON_PERSONALIZED){
Bundle extras = new Bundle();
extras.putString("npa", "1");
mInterstitialAd.loadAd(new AdRequest.Builder()
.addNetworkExtrasBundle(AdMobAdapter.class,extras).build());
} else {
mInterstitialAd.loadAd(new AdRequest.Builder().build());
}
}
//Toolbar search edit text will be enabled in below case
if (urlType.equals(EnumVal.Type.SEARCHED_TEXT.toString())){
searchBarLayout.setVisibility(View.VISIBLE);
searchIcon.setImageResource(R.drawable.close_icon);
searchEditText.setText(searchedText);
searchEditText.clearFocus();
searchEditText.setCursorVisible(false);
this.getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_ALWAYS_HIDDEN);
if (searchEditText.hasFocus())
searchEditText.setCursorVisible(true);
}
searchEditText.addTextChangedListener(new TextWatcher() {
#Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
}
#Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
}
#Override
public void afterTextChanged(Editable s) {
clearEditText.setVisibility(View.VISIBLE);
}
});
//Navigation view in toolbar
navRecView.setLayoutManager(new LinearLayoutManager(this));
mViewModel = ViewModelProviders.of(this).get(DbViewModel.class);
mViewModel.getSitesWithClicksByIsShown().observe(this, new Observer<List<SitesWithClicks>>() {
#Override
public void onChanged(#Nullable List<SitesWithClicks> sitesWithClicks) {
if (sitesWithClicks!= null && sitesWithClicks.size()>0){
int reArrSite = prefSingleton.getStorage().getInt(Constants.STORAGE_REARRANGESITE_NAV,
Constants.SORTING_PRIORITY);
sitesWithClicks = Utility.sortSitesData(reArrSite, sitesWithClicks);
navAdapter = new ListRecViewAdapter(EnumVal.DialogType.NAVBAR_ITEMS,
sitesWithClicks, WebsiteView.this);
navRecView.setAdapter(navAdapter);
}
}
});
}
Open-fragment method:
public void openFragment(String url, EnumVal.FragStatus fragStatus, String toOpenTag){
if(navFrame.getVisibility() == View.VISIBLE)
downArrow.performClick();
if(fragStatus == EnumVal.FragStatus.NEW){
String fragTag = getNextFragTag();
WebsiteViewFragment fragment = WebsiteViewFragment.newInstance(url, fragTag);
FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
if(fragCounter == 1){
fragmentTransaction.replace(R.id.fragment, fragment, fragTag);
currentFrag = fragTag;
} else {
if(getSupportFragmentManager().findFragmentByTag(currentFrag) != null){
fragmentTransaction.setCustomAnimations(android.R.animator.fade_in, android.R.animator.fade_out);
fragmentTransaction.hide(getSupportFragmentManager().findFragmentByTag(currentFrag));
}
fragmentTransaction.add(R.id.fragment, fragment, fragTag);
currentFrag = fragTag;
}
fragmentTransaction.commit();
fragTags.add(new TabDetail(fragTag,"Tab - 1",null));
} else if (fragStatus == EnumVal.FragStatus.OLD){
FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
if(getSupportFragmentManager().findFragmentByTag(currentFrag) != null){
fragmentTransaction.setCustomAnimations(android.R.animator.fade_in, android.R.animator.fade_out);
fragmentTransaction.hide(getSupportFragmentManager().findFragmentByTag(currentFrag));
}
fragmentTransaction.show(getSupportFragmentManager().findFragmentByTag(toOpenTag));
fragmentTransaction.commit();
currentFrag = toOpenTag;
}
}
And Fragment has just Webview in it where webview is loading lot of websettings. But thing is reaching till fragment is taking time ,like user clicks from main activity and after about 0.6 seconds, fragment is opening while activity which has fragment is taking just 0.1 second to open so this time is (maybe) related to attaching fragment or something?
Can anyone please explain me, where am I making mistake?
I had some doubt regarding this:
Is the problem webview (in fragment), which has a bunch of websettings ?
Is attaching fragment to activity-2 taking more time?
Is UI part of activity-2 taking time (like toolbar setup which has 4 buttons) and after that fragment is attaching to it, which is resulting in more time consumption ?
Or it is a normal situation ?
Can someone, please, explain me the way to make it to <0.2 seconds for whole tasks? Thanks in advance.

Intent from fragment to mainActivity

I'm trying to send intent from fragment to MainActivity. But while doing startActivity(intent) at this point app is working good but every time I click on listview fragment is refreshing and listview starts from 0 index again. What is the best way to send the intent from the fragment?
I have two fragments and one main activity. So the user can see both the fragments at the same time. fist fragment is a list of cities and the second fragment is the description of the city.
Thank you very much for your time and assistance in this matter.
Please check my code below:
public class MainActivity extends AppCompatActivity {
private String cityName;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
fragmentManage();
}
public void fragmentManage() {
CityInformationFragment cityInformationFragment = new
CityInformationFragment();
CityList cityList = new CityList();
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction fragmentTransaction =
fragmentManager.beginTransaction();
fragmentTransaction.add(R.id.fragment2holder, cityList);
fragmentTransaction.add(R.id.fragment1holder, cityInformationFragment);
fragmentTransaction.commit();
Intent intent = getIntent();
cityName = intent.getStringExtra(CityList.PUT_EXTRA_KEY);
Bundle bundle = new Bundle();
bundle.putString(CityList.PUT_EXTRA_KEY, cityName);
cityInformationFragment.setArguments(bundle);
}
}
My CityList fragment:
public class CityList extends Fragment implements
AdapterView.OnItemClickListener {
String[] cityList;
ListView listView;
protected static final String PUT_EXTRA_KEY = "city";
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup
container, Bundle savedInstanceState) {
// arrayAdapter.addAll(cityList);
cityList = getResources().getStringArray(R.array.cities);
ArrayAdapter<CharSequence> arrayAdapter = new ArrayAdapter <CharSequence>(getActivity(), android.R.layout.simple_list_item_1, cityList);
View view = inflater.inflate(R.layout.citylistframent, container, false);
listView = (ListView) view.findViewById(R.id.cityList);
listView.setAdapter(arrayAdapter);
listView.setOnItemClickListener(this);
return view;
}
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
TextView textView = (TextView) view;
String city = textView.getText().toString();
Intent intent = new Intent(getActivity(), MainActivity.class);
intent.putExtra(PUT_EXTRA_KEY, city);
startActivity(intent);
}
}
My CityInformationFragment:
public class CityInformationFragment extends Fragment {
String vancouver = "Vancouver, a bustling west coast seaport in British Columbia, is among Canada’s densest, most ethnically diverse cities." +
" A popular filming location, it’s surrounded by mountains, and also has thriving art, theatre and music scenes." +
" Vancouver Art Gallery is known for its works by regional artists, while the Museum of Anthropology houses preeminent First Nations collections.";
String calgary = "Calgary, a cosmopolitan Alberta city with numerous skyscrapers, owes its rapid growth to its status as the centre of Canada’s oil industry. However," +
" it’s still steeped in the western culture that earned it the nickname “Cowtown,”" +
" evident in the Calgary Stampede, its massive July rodeo and festival that grew out of the farming exhibitions once presented here.";
String kamloops = "Kamloops is a Canadian city in British Columbia, where the North and South Thompson rivers meet." +
" Sun Peaks Resort’s hiking trails, bike park and numerous ski runs lie to the northeast. Cougars and bears inhabit the British Columbia Wildlife Park east of town." +
" West, above Kamloops Lake are clay hoodoos (or spires). The riverside Secwepemc Museum & Heritage Park features the remains of a 2,000-year-old village.";
String toronto = "Toronto, the capital of the province of Ontario, is a major Canadian city along Lake Ontario’s northwestern shore." +
" It's a dynamic metropolis with a core of soaring skyscrapers, all dwarfed by the iconic, free-standing CN Tower. " +
"Toronto also has many green spaces, from the orderly oval of Queen’s Park to 400-acre High Park and its trails, sports facilities and zoo.";
String saskatoon = "Saskatoon is a city straddling the South Saskatchewan River in Saskatchewan, Canada. " +
"North along the riverside Meewasin Trail is Wanuskewin Heritage Park, with exhibitions exploring indigenous culture. " +
"On the trail’s southern stretch, native wildlife inhabit the prairie grasslands of Beaver Creek Conservation Area. " +
"East of the river, the Saskatoon Forestry Farm Park & Zoo has manicured gardens and a children’s zoo.";
TextView textView;
String cityName = "";
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.cityinformation, container, false);
textView = view.findViewById(R.id.cityInformation);
cityName = getArguments().getString(CityList.PUT_EXTRA_KEY);
// Toast.makeText(getContext(), cityName, Toast.LENGTH_SHORT).show();
setInformation();
return view;
}
public String getVancouver() {
return vancouver;
}
public String getCalgary() {
return calgary;
}
public String getKamloops() {
return kamloops;
}
public String getToronto() {
return toronto;
}
public String getSaskatoon() {
return saskatoon;
}
public void setInformation() {
if (cityName != null) {
if (cityName.equals("")) {
textView.setText(getKamloops());
} else if (cityName.equals("Calgary")) {
textView.setText(getCalgary());
} else if (cityName.equals("Kamloops")) {
textView.setText(getKamloops());
} else if(cityName.equals("Calgary")) {
textView.setText(getCalgary());
} else if(cityName.equals("Saskatoon")){
textView.setText(getSaskatoon());
} else if(cityName.equals("Toronto")) {
textView.setText(getToronto());
} else if(cityName.equals("Vancouver")){
textView.setText(getVancouver());
}
} else {
textView.setText(getKamloops());
}
}
}

Use eventbus it will solve your problem and you dont need to call activity, fragments are working inside activity read documentation you understand me

Intents are only usable for sending data on an Activity level. To pass data between fragments we need to create our own interfaces.
As describe here Communicating with Other Fragments

You need to create a listener/callback in your Activity and Fragment. Whenever there is a change that you want to pass to Activity, send it via the listener. Read more at Communicating with Other Fragments.
First, define the listener with interface in the Fragment:
public class CityList extends Fragment implements AdapterView.OnItemClickListener {
private CityListListener mListener;
// Host Activity must implement this listener.
public interface CityListListener {
public void onItemClicked(String city);
}
#Override
public void onAttach(Context context) {
super.onAttach(context);
// Makes sure that the host activity has implemented the listener
try {
mListener = (CityListListener) context;
} catch (ClassCastException e) {
throw new ClassCastException(context.toString()
+ " must implement CityListListener");
}
}
...
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
TextView textView = (TextView) view;
String city = textView.getText().toString();
// tell the host Activity about the item click.
mListener.onItemClicked(city);
}
}
Now, you need to implement the listener in your Activity:
public class MainActivity extends AppCompatActivity
implements CityList.CityListListener {
...
#Override
public void onItemClicked(String city) {
// This will listen to every item click in CityList Fragment
// Do something about the city.
}
}

Android ListView not refreshing after dataset changed, though I have used the Adapter.notifyDataSetChanged()

I know similar questions had been asked here a couple of times, but none of them could help me with my problem, so I will just have to ask again.
What I have is an app that has a fragment that holds a ListView in the main activity and I used a PullableListView so that when I drag the ListView up, it will trigger the onLoadMore() callback method to load more data from the server. Once data loaded, the data will be saved to a SQLiteDB and then used by the ListView to show the updated data.
The is my PullableListViewFragment.java:
public class PullableListViewFragment extends Fragment implements
OnItemClickListener {
private ListView listView;
private PullToRefreshLayout ptrl;
private MissionDB mMissionDB;
private List<MissionEntity> mData;
private MissionListAdapter mAdapter;
/**
* Specify the exact mission that will be displayed in MissionDetailActivity
*/
private int mIndexOfMission;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View pullableLayout = inflater.inflate(R.layout.pullable_layout, container, false);
listView = (ListView) pullableLayout.findViewById(R.id.content_view);
listView.setDivider(null);
ptrl = (PullToRefreshLayout) pullableLayout.findViewById(R.id.refresh_view);
ptrl.setOnRefreshListener(new RefreshListener());
loadData();
Log.d(Constants.LOG_TAG, "onCreateView Called from PullableListViewFragment");
return pullableLayout;
}
/**
* Initialise ListView
*/
#Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
mAdapter = new MissionListAdapter(getActivity(), mData);
listView.setAdapter(mAdapter);
listView.setOnItemClickListener(this);
mAdapter.notifyDataSetChanged();
Log.d(Constants.LOG_TAG, "onActivityCreated Called from PullableListViewFragment");
}
/**
* Load data from db
*/
private void loadData() {
mData = new ArrayList<>();
mMissionDB = MissionDB.getInstance(MyApplication.getContext());
mData = mMissionDB.loadMission();
}
/**
* OnItemClick event
*/
#Override
public void onItemClick(AdapterView<?> parent, View view, int position,
long id) {
Intent intent = new Intent(getActivity(), MissionDetailActivity.class);
mIndexOfMission = mData.get((int) id).getId();
intent.putExtra("Position", mIndexOfMission);
startActivity(intent);
}
}
And this is the RefreshListener.java:
public class RefreshListener implements PullToRefreshLayout.OnRefreshListener {
private MissionDB mMissionDB = MissionDB.getInstance(MyApplication.getContext());
#Override
public void onLoadMore(final PullToRefreshLayout pullToRefreshLayout) {
// LoadMore
new Handler() {
#Override
public void handleMessage(Message msg) {
/** When drag up, load more mission that is older and not out of date */
mMissionDB.open();
int id = mMissionDB.getMaxOrMinId("MIN");
final JSONObject oldMission = new JSONObject();
try {
oldMission.put("platform", "1");
oldMission.put("more", 0);
oldMission.put("id", id);
oldMission.put("size", 1);
} catch (JSONException e) {
e.printStackTrace();
}
Thread t = new Thread(new Runnable() {
#Override
public void run() {
HttpRequest.sendHttpRequest(Constants.PULLORDRAG_TO_LOAD_MISSION_URL, oldMission, new HttpCallbackListener() {
#Override
public void onFinish(String response) {
MissionEntity mMission = new MissionEntity();
/** Save new mission to mission database */
try {
JSONObject jsonObject = new JSONObject(response);
JSONArray missionList = jsonObject.getJSONArray("taskList");
for (int i = 0; i < missionList.length(); i++) {
JSONObject mission = missionList.getJSONObject(i);
mMission.setId(mission.getInt("id"));
mMission.setDownloadUrl(mission.getString("appPath"));
mMission.setCreateTime(mission.getString("taskId"));
mMission.setImageUrl(mission.getString("appImg"));
mMission.setTitleName(mission.getString("appName"));
mMission.setRemainTime("Remain： 1d 11h 23m 36s");
mMission.setParticipant("135");
mMission.setCreator("Google");
mMission.setRequirement(mission.getString("description"));
mMission.setRewards("TODO");
mMission.setAttention("TODO");
mMission.setValidDate(mission.getString("deadline"));
mMission.setAccepted("0");
mMission.setCollected("0");
mMission.setAccomplished("0");
mMissionDB.saveMission(mMission);
}
} catch (JSONException e) {
e.printStackTrace();
}
}
#Override
public void onError(Exception e) {
e.printStackTrace();
Log.e(Constants.LOG_TAG, "Error while loading more");
}
});
}
});
try {
t.start();
t.join();
} catch (InterruptedException e) {
e.printStackTrace();
}
pullToRefreshLayout.loadmoreFinish(PullToRefreshLayout.SUCCEED);
//==================Update 1==================
ListView list = (ListView) pullToRefreshLayout.findViewById(R.id.content_view);
List<MissionEntity> missionList = mMissionDB.loadMission();
Log.d(Constants.LOG_TAG, "mission size" + missionList.size());
MissionListAdapter adapter = (MissionListAdapter) list.getAdapter();
adapter.setData(missionList);
adapter.notifyDataSetChanged();
list.setAdapter(adapter);
//==================Update 1==================
}
}.sendEmptyMessageDelayed(0, 1000);
}
}
The PullToRefreshLayout is a custom RelativeLayout that defined a inner interface OnRefreshListener that will be called once the onLoadMore() callback method is called.
The ListView I use in the Fragment is a PullableListView that implemented a Pullable interface that can drag up.
My Pullable.java:
public interface Pullable
{
/**
* If pull up is not needed, set canPullUp to false
*
* #return true if the View can pull up
*/
boolean canPullUp();
}
This is the fragment's layout.xml:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#f2f2f2"
android:orientation="vertical">
<View
android:layout_width="match_parent"
android:layout_height="5dp" />
<pulltorefresh.PullToRefreshLayout
android:id="#+id/refresh_view"
android:layout_marginLeft="8dp"
android:layout_marginRight="8dp"
android:layout_width="match_parent"
android:layout_height="match_parent">
<include layout="#layout/refresh_head"/>
<!-- Supports all view that implemented the Pullable interface -->
<pulltorefresh.PullableListView
android:id="#+id/content_view"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
<include layout="#layout/load_more"/>
</pulltorefresh.PullToRefreshLayout>
</LinearLayout>
The problem is when the data in the SQLiteDB is changed after the onLoadMore() method, the ListView in the fragment doesn't refresh itself unless I navigate to another fragment within the same main activity and then navigate back.
I tired all the ways I can find here and none of them help.
Could anyone tell me how can I make the ListView refresh itself when the data in the SQLiteDB changed.
[Update 1] I've added some code in the onLoadMore() callback, the size of the data remains the same after I get some data from the server, i think this is the problem why the ListVie is not refreshing, what's interesting is if I put a Thread.sleep(500) before mMission.loadMission() the size of the data is correct and everything is fine. Any idea why?

In onLoadMore method, you just only load data and save into database. After load data, you should update the data source of the adapter and call adapter.notifyDataSetChanged() to refresh the listview. or you can notify the fragment to reload data from database.

Make sure it get data when load more first. And I think your mMissionDB is changed indeed, but what about mData? Your adapter is use mData as datasource actually, so you should update mData, and call adapter.notifyDataSetChanged() to refresh the listview. Hope it can help you.