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RecyclerView not showing any items unless i press homebutton and reenter the activity

The app doesn't show anything in the recycler view the first time I open it, but it shows the items after I press the home button and then press the overview button and open the app from there
here is the code in mainActivity
public class MainActivity extends AppCompatActivity {
private RecyclerView mRecyclerView;
private RecyclerView.Adapter mAdapter;
private RecyclerView.LayoutManager mlayoutManager;
private ProgressDialog dialog;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
final ArrayList<String> countryNmaeList =new ArrayList<>();
final ArrayList<countryItem> countryList = new ArrayList<>();
final ProgressDialog dialog = new ProgressDialog(this);
dialog.setMessage("Loading data");
mRecyclerView = findViewById(R.id.recyclerView);
mAdapter=new countryAdapter(countryList);
mlayoutManager=new LinearLayoutManager(this);
mRecyclerView.setLayoutManager(mlayoutManager);
dialog.show();
OkHttpClient client = new OkHttpClient();
Request request = new Request.Builder()
.url("https://covid-193.p.rapidapi.com/statistics")
.get()
.addHeader("x-rapidapi-host", "covid-193.p.rapidapi.com")
.addHeader("x-rapidapi-key", "xxxxxxxxxxxxx")
.build();
client.newCall(request).enqueue(new Callback() {
#Override
public void onFailure(#NotNull Call call, #NotNull IOException e) {
}
#Override
public void onResponse(#NotNull Call call, #NotNull Response response) throws IOException {
dialog.dismiss();
String response1=response.body().string();
try {
//geting Jason object
JSONObject jsonObject=new JSONObject(response1);
JSONArray jsonArray = jsonObject.getJSONArray("response");
for (int i=0;i<jsonArray.length();i++){
JSONObject country = jsonArray.getJSONObject(i);
JSONObject cases = country.getJSONObject("cases");
int activecaseint = cases.getInt("active");
int recoveredint =cases.getInt("recovered");
JSONObject death= country.getJSONObject("deaths");
int dtotal = death.getInt("total");
//adding items into country items
countryList.add(new countryItem(country.getString("country"),String.valueOf(activecaseint),String.valueOf(recoveredint),String.valueOf(dtotal)));
}
} catch (JSONException e) {
e.printStackTrace();
}
}
});
//nottifying the dataset changed
mAdapter.notifyDataSetChanged();
mRecyclerView.setAdapter(mAdapter);
}
}
here is my adapter activity
countryAdapter.java
public class countryAdapter extends RecyclerView.Adapter<countryAdapter.countryViewHolder> {
private ArrayList<countryItem> mCountryList;
public static class countryViewHolder extends RecyclerView.ViewHolder{
public TextView mCountryName;
public TextView mActivePatients;
public TextView mRecovered;
public TextView mDeath;
public countryViewHolder(#NonNull View itemView) {
super(itemView);
mCountryName=itemView.findViewById(R.id.CountyNameTv);
mActivePatients=itemView.findViewById(R.id.activePatientsTv);
mRecovered=itemView.findViewById(R.id.recoveredTv);
mDeath=itemView.findViewById(R.id.deathTv);
}
}
public countryAdapter(ArrayList<countryItem> countryList){
mCountryList = countryList;
}
#NonNull
#Override
public countryViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View v= LayoutInflater.from(parent.getContext()).inflate(R.layout.itemview,parent,false);
countryViewHolder cvh =new countryViewHolder(v);
return cvh;
}
#Override
public void onBindViewHolder(#NonNull countryViewHolder holder, int position) {
countryItem currentItem=mCountryList.get(position);
holder.mCountryName.setText(currentItem.getCountryname());
holder.mActivePatients.setText(currentItem.getActivePatients());
holder.mRecovered.setText(currentItem.getRecovered());
holder.mDeath.setText(currentItem.getDeath());
}
#Override
public int getItemCount() {
return mCountryList.size();
}
public void swapData(ArrayList<countryItem> list) {
if (list != null) {
this.mCountryList.clear();
this.mCountryList.addAll(list);
notifyDataSetChanged();
}
}
}
i have tried putting notifyDataSetChanged inside the try but that didn't work. i hope you can find a way to fix this.

When you have new datalist update after adding it in list as:
public void onResponse(#NotNull Call call, #NotNull Response response) throws IOException {
dialog.dismiss();
String response1=response.body().string();
try {
//geting Jason object
JSONObject jsonObject=new JSONObject(response1);
JSONArray jsonArray = jsonObject.getJSONArray("response");
for (int i=0;i<jsonArray.length();i++){
JSONObject country = jsonArray.getJSONObject(i);
JSONObject cases = country.getJSONObject("cases");
int activecaseint = cases.getInt("active");
int recoveredint =cases.getInt("recovered");
JSONObject death= country.getJSONObject("deaths");
int dtotal = death.getInt("total");
//adding items into country items
countryList.add(new countryItem(country.getString("country"),String.valueOf(activecaseint),String.valueOf(recoveredint),String.valueOf(dtotal)));
}
//adapter.swapData(countryList);
updateData(countryList);
} catch (JSONException e) {
e.printStackTrace();
}
}
you can comment out following line:
mAdapter.notifyDataSetChanged();
Add this function in your adapter class and call it when you need to update list:
public void swapData(ArrayList<countryItem> list) {
if (list != null) {
this.arrayList.clear();
this.arrayList.addAll(list);
notifyDataSetChanged();
}
}
In your global object declaration change type of adapter to:
private countryAdapter mAdapter;
add this method in mainActivity and call when you want to update data:
public void updateData(ArrayList<countryItem> countryList) {
new Handler(Looper.getMainLooper()).post(new Runnable() {
#Override
public void run() {
mAdapter.swapData(countryList);
}
});
}

Instead of calling mAdapter.notifyDataSetChanged() at the end of onCreate() you should call it in onRespone() when the new data got set.
#Override
public void onResponse(#NotNull Call call, #NotNull Response response) throws IOException {
dialog.dismiss();
String response1=response.body().string();
try {
//geting Jason object
JSONObject jsonObject=new JSONObject(response1);
JSONArray jsonArray = jsonObject.getJSONArray("response");
for (int i=0;i<jsonArray.length();i++){
JSONObject country = jsonArray.getJSONObject(i);
JSONObject cases = country.getJSONObject("cases");
int activecaseint = cases.getInt("active");
int recoveredint =cases.getInt("recovered");
JSONObject death= country.getJSONObject("deaths");
int dtotal = death.getInt("total");
//adding items into country items
countryList.add(new countryItem(country.getString("country"),String.valueOf(activecaseint),String.valueOf(recoveredint),String.valueOf(dtotal)));
}
mAdapter.notifyDataSetChanged(); // ← notify adapter here!
} catch (JSONException e) {
e.printStackTrace();
}
}

Selecting one from radio group value and scrolling down and some item selected automatically in Recycler View( beginner)

I am making an attendance system where I take the attendance using RadioGroup with two options. When I select some radio button and scroll down some other radio button gets auto-selected. If I change them upper ones also get changed.
Main class
public class TeacherAttendanceActivity extends AppCompatActivity implements AttendanceAdapter.AttendanceAdapterListner {
public static TeacherAttendanceActivity teacherAttendanceActivity;
private static final String TAG = TeacherAttendanceActivity.class.getSimpleName();
List<AttendanceModel> listItems;
private RecyclerView recyclerView;
private RecyclerView.Adapter adapter;
private AttendanceAdapter attendanceAdapter;
ProgressDialog progressDialog;
private SQLiteHandler db;
private SessionManager session;
private SearchView searchView;
Button btnSubmit;
JSONObject mainObj = new JSONObject();
// date
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
String currentDateandTime = sdf.format(new Date());
String class_id,title;
Boolean Error;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_teacher_attendance);
//get data from intent
class_id = super.getIntent().getExtras().getString("id"); //class_id
title = super.getIntent().getExtras().getString("title");
getSupportActionBar().setTitle("Class: "+title+", Date: "+currentDateandTime );
// SqLite database handler
db = new SQLiteHandler(getApplicationContext());
// session manager
session = new SessionManager(getApplicationContext());
btnSubmit=findViewById(R.id.buttonAttendanceSubmit);
btnSubmit.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Error=false;
Gson gson=new Gson();
final String newDataArray=gson.toJson(listItems); // dataarray is list aaray
for (int i = 0; i < AttendanceAdapter.listItems.size(); i++){
if(AttendanceAdapter.listItems.get(i).getAttendance()==null){
Toast.makeText(TeacherAttendanceActivity.this, "Check attendance at roll:"+AttendanceAdapter.listItems.get(i).getRoll(), Toast.LENGTH_SHORT).show();
Error =true;
break;
}
}
if (!Error){
request(class_id,currentDateandTime,newDataArray);
}
}
});
listItems = new ArrayList<>();
attendanceAdapter = new AttendanceAdapter(listItems, this, (AttendanceAdapter.AttendanceAdapterListner) this);
recyclerView = (RecyclerView) findViewById(R.id.list_attendance);
recyclerView.setLayoutManager(new LinearLayoutManager(TeacherAttendanceActivity.this));
progressDialog = new ProgressDialog(this);
teacherAttendanceActivity = this;
//refresh_list(class_id);
}
#Override
protected void onStart() {
refresh_list(class_id);
super.onStart();
}
#Override
public void onAttendanceAdapterSelected(AttendanceModel model) {
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.refresh, menu);
getMenuInflater().inflate(R.menu.tool_bar, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
switch (id){
case R.id.action_settings:
Toast.makeText(getApplicationContext(),"Sittings",Toast.LENGTH_LONG).show();
return true;
case R.id.action_logout:
logoutUser();
return true;
case R.id.action_about:
Toast.makeText(getApplicationContext(),"About",Toast.LENGTH_LONG).show();
return true;
case R.id.action_devinfo:
Toast.makeText(getApplicationContext(),"Dev info",Toast.LENGTH_LONG).show();
return true;
case R.id.refresh:
refresh_list(class_id);
return true;
default:
return super.onOptionsItemSelected(item);
}
}
void logoutUser() {
session.setLogin(false);
db.deleteUsers();
// Launching the login activity
Intent intent = new Intent(this, MainActivity.class);
startActivity(intent);
finish();
}
// refresh list
public void refresh_list(String id) {
// this method refresh list and get the json data
listItems.clear();
// adapter = new MyAdapter(listItems,getApplicationContext());
recyclerView.setAdapter(attendanceAdapter);
recyclerView.setItemAnimator(new DefaultItemAnimator());
progressDialog.setMessage("Loading");
progressDialog.show();
StringRequest stringRequest = new StringRequest(Request.Method.GET, ApiConfig.URL_TEACHER_ATTENDANCE+id, new Response.Listener<String>() {
#Override
public void onResponse(String response) {
progressDialog.dismiss();
try {
progressDialog.hide();
JSONObject jsonObject = new JSONObject(response);
JSONArray jsonArray = jsonObject.getJSONArray("Data"); // finding data
Log.d(TAG, String.valueOf(jsonObject));
int len = jsonArray.length();
for (int i = 0; i < len; i++) {
JSONObject o = jsonArray.getJSONObject(i);
AttendanceModel item = new AttendanceModel(
o.getString("id"),
o.getString("name"),
o.getString("roll"),
o.getString("class_id"),
o.getString("status"),
null
);
listItems.add(item);
//adapter = new MyAdapter(listItems,getApplicationContext());
recyclerView.setAdapter(attendanceAdapter); // setting them in list view
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}, new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
progressDialog.hide();
Toast.makeText(TeacherAttendanceActivity.this, "Failed", Toast.LENGTH_SHORT).show();
}
}) {
/** Passing some request headers* */
#Override
public Map getHeaders() throws AuthFailureError {
SQLiteHandler db = new SQLiteHandler(getApplicationContext());
HashMap<String,String> userDetail= db.getUserDetails();
String userToken = userDetail.get("token");
Log.d(TAG, String.valueOf(userToken));
HashMap headers = new HashMap();
headers.put("Accept", "application/json");
headers.put("Authorization", "Bearer "+userToken);
return headers;
}
};
stringRequest.setShouldCache(false);
VolleyRequest.getInstance(TeacherAttendanceActivity.this).addToRequestQueue(stringRequest);
}
// take attendance
private void request( final String classId,final String date,final String data ) {
progressDialog.setMessage("Taking attendance");
showDialog();
StringRequest strReq = new StringRequest(Request.Method.POST,
ApiConfig.URL_TEACHER_ATTENDANCE_STORE, new Response.Listener<String>() {
#Override
public void onResponse(String response) {
Log.d(TAG, "Login Response: " + response);
hideDialog();
try {
JSONObject jObj = new JSONObject(response);
boolean error = jObj.getBoolean("error");
// Check for error node in json
if (!error) {
String attendance = jObj.getString("Attendance");
Toast.makeText(TeacherAttendanceActivity.this, attendance, Toast.LENGTH_LONG).show();
finish();
} else {
// Error in login. Get the error message
String errorMsg = jObj.getString("message");
Toast.makeText(TeacherAttendanceActivity.this,
errorMsg, Toast.LENGTH_LONG).show();
}
} catch (JSONException e) {
// JSON error
e.printStackTrace();
Toast.makeText(TeacherAttendanceActivity.this, "Json error: " + e.getMessage(), Toast.LENGTH_LONG).show();
}
}
}, new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
Log.e(TAG, "Login Error: " + error.getMessage());
Toast.makeText(TeacherAttendanceActivity.this,
error.getMessage(), Toast.LENGTH_LONG).show();
hideDialog();
}
}) {
/** Passing some request headers* */
#Override
public Map getHeaders() throws AuthFailureError {
SQLiteHandler db = new SQLiteHandler(TeacherAttendanceActivity.this);
HashMap<String,String> userDetail= db.getUserDetails();
String userToken = userDetail.get("token");
Log.d(TAG, String.valueOf(userToken));
HashMap headers = new HashMap();
headers.put("Accept", "application/json");
headers.put("Authorization", "Bearer "+userToken);
return headers;
}
#Override
protected Map<String, String> getParams() {
// Posting parameters to login url
Map<String, String> params = new HashMap<String, String>();
params.put("class_id", classId);
params.put("date", date);
params.put("data", data);
return params;
}
};
strReq.setShouldCache(false);
// Adding request to request queue
VolleyRequest.getInstance(TeacherAttendanceActivity.this).addToRequestQueue(strReq);
}
private void showDialog() {
if (!progressDialog.isShowing())
progressDialog.show();
}
private void hideDialog() {
if (progressDialog.isShowing())
progressDialog.dismiss();
}
}
Model class
'model class for convenient '
public class AttendanceModel {
String id,name,roll,classId,previousAttendance,attendance;
public AttendanceModel(String id, String name,String roll, String classId,String previousAttendance,String attedance ){
this.id = id;
this.name = name;
this.classId =classId;
this.roll=roll;
this.attendance=attedance;
this.previousAttendance=previousAttendance;
}
public String getAttendance() {
return attendance;
}
public String getId() {
return id;
}
public String getName() {
return name;
}
public String getRoll() {
return roll;
}
public String getClassId() {
return classId;
}
public String getPreviousAttendance(){return previousAttendance;}
public void setId(String id) {
this.id = id;
}
public void setName(String name) {
this.name = name;
}
public void setRoll(String roll) {
this.roll = roll;
}
public void setClassId(String classId) {
this.classId = classId;
}
public void setPreviousAttendance(String previousAttendance) {
this.previousAttendance = previousAttendance;
}
public void setAttendance(String attendance) {
this.attendance = attendance;
}
}
Adapter class
' adapter class '
public class AttendanceAdapter extends RecyclerView.Adapter<AttendanceAdapter.ViewHolder> implements Filterable
{
// date
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
String currentDateandTime = sdf.format(new Date());
private static final String TAG = AttendanceAdapter.class.getSimpleName();
public static List<AttendanceModel> listItems;
private List<AttendanceModel> listItemsFiltered;
private Context context;
private ProgressDialog dialog;
private AttendanceAdapter.AttendanceAdapterListner listner;
private ProgressDialog pDialog;
private SQLiteHandler db;
public static JSONObject jo = new JSONObject();
public static JSONArray ja = new JSONArray();
public AttendanceAdapter(List<AttendanceModel> listItems, Context context, AttendanceAdapter.AttendanceAdapterListner listner) {
this.listItems = listItems;
this.listner=listner;
this.context = context;
this.listItemsFiltered =listItems;
// SqLite database handler
db = new SQLiteHandler(context);
// Progress dialog
pDialog = new ProgressDialog(context);
}
#Override
public Filter getFilter() {
return new Filter() {
#Override
protected FilterResults performFiltering(CharSequence charSequence) {
String charString = charSequence.toString();
if (charString.isEmpty()) {
listItemsFiltered = listItems;
} else {
List<AttendanceModel> filteredList = new ArrayList<>();
for (AttendanceModel row : listItems) {
// name match condition. this might differ depending on your requirement
// here we are looking for name or phone number match
if (row.getName().toUpperCase().contains(charSequence.toString().toUpperCase())||row.getName().toLowerCase().contains(charSequence.toString().toLowerCase())) {
filteredList.add(row);
}
}
listItemsFiltered = filteredList;
}
FilterResults filterResults = new FilterResults();
filterResults.values = listItemsFiltered;
return filterResults;
}
#Override
protected void publishResults(CharSequence charSequence, FilterResults filterResults) {
listItemsFiltered = (ArrayList<AttendanceModel>) filterResults.values;
notifyDataSetChanged();
}
};
}
public class ViewHolder extends RecyclerView.ViewHolder {
public TextView name;
public TextView roll;
public TextView previous;
RadioGroup radioAttendance;
RadioButton radioAttendancePresent,radioAttendanceAbsent;
public CardView card_view;
public ViewHolder(View itemView) {
super(itemView);
name= (TextView) itemView.findViewById(R.id.textViewAttendanceStudentName);
roll = (TextView) itemView.findViewById(R.id.textViewAttendanceStudentRoll);
previous = (TextView) itemView.findViewById(R.id.textViewAttendanceStudentPreviousStatus);
radioAttendance = itemView.findViewById(R.id.radioAttendance);
radioAttendancePresent =itemView.findViewById(R.id.radioAttendancePresent);
radioAttendanceAbsent =itemView.findViewById(R.id.radioAttendanceAbsent);
//card_view = (CardView) itemView.findViewById(R.id.class_card_view); // card view for on click method
itemView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick( View view) {
// send selected contact in callback
listner.onAttendanceAdapterSelected(listItemsFiltered.get(getAdapterPosition())); // selecting cardview and position (model)
}
});
radioAttendance.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
#Override
public void onCheckedChanged(RadioGroup radioGroup, int i) {
//Toast.makeText(TeacherAttendanceActivity.this, toString(i), Toast.LENGTH_SHORT).show();
// Toast.makeText(context,"clicked at position"+i+" "+id+""+name,Toast.LENGTH_SHORT).show();
if(radioAttendancePresent.isChecked())
{
listItems.get(getAdapterPosition()).setAttendance("present");
}
else {
listItems.get(getAdapterPosition()).setAttendance("absent");
}
}
});
}
}
#Override
public AttendanceAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.attendance_list, parent, false);
return new AttendanceAdapter.ViewHolder(v);
}
#Override
public void onBindViewHolder (final AttendanceAdapter.ViewHolder holder, final int position) {
final AttendanceModel listItem = listItemsFiltered.get(position);
holder.name.setText(listItem.getName());
holder.roll.setText(listItem.getRoll());
holder.previous.setText(listItem.getPreviousAttendance());
}
public interface AttendanceAdapterListner {
void onAttendanceAdapterSelected(AttendanceModel model); // sending cardview to say the dialoge and model for sending context
}
#Override
public int getItemCount() {
return listItemsFiltered.size();
}
private void showDialog() {
if (!pDialog.isShowing())
pDialog.show();
}
private void hideDialog() {
if (pDialog.isShowing())
pDialog.dismiss();
}
}

Your problem would be solved by making small changes to your Recycler view adapter, please do not disable recyclable property, this makes your recycler view a glorified list view.
I can see you tried using a sparse boolean array to hold the state of the radio buttons, that is good but you do not need that too. The idea behind using a Sparse boolean array is to keep the state of each item in the recycler view so that when they are recycled you still have a reference to what the state of each item is.
In your adapter you already have something that we can use to know the state, that is the attendance property of your model, in that case, you can set the state of your checkboxes by checking if the attendance property is present or absent.
One more thing about your code is that you are using the onCheckChangedListener as a click event handler for your radio button, you should not use this because it responds to all check changed events, even if it is triggered from code and not from user action, so when you bind your view and you set any of your radio buttons as checked or unchecked, it calls this callback.
Here is a modified version of your ViewHolder class that solves this issue by applying the solution above.
public class ViewHolder extends RecyclerView.ViewHolder {
public TextView name;
public TextView roll;
public TextView previous;
RadioGroup radioAttendance;
RadioButton radioAttendancePresent, radioAttendanceAbsent;
public CardView card_view;
public ViewHolder(View itemView) {
super(itemView);
name = (TextView) itemView.findViewById(R.id.textViewAttendanceStudentName);
roll = (TextView) itemView.findViewById(R.id.textViewAttendanceStudentRoll);
previous = (TextView) itemView.findViewById(R.id.textViewAttendanceStudentPreviousStatus);
radioAttendance = itemView.findViewById(R.id.radioAttendance);
radioAttendancePresent = itemView.findViewById(R.id.radioAttendancePresent);
radioAttendanceAbsent = itemView.findViewById(R.id.radioAttendanceAbsent);
radioAttendancePresent.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
radioAttendancePresent.setChecked(true);
listItems.get(getAdapterPosition()).setAttendance("present");
}
});
radioAttendanceAbsent.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
radioAttendanceAbsent.setChecked(true);
listItems.get(getAdapterPosition()).setAttendance("absent");
}
});
}
void bind(int position) {
// use the sparse boolean array to check
if (listItems.get(position).getAttendance() != null) {
if (listItems.get(position).getAttendance().equals("present")) {
radioAttendancePresent.setChecked(true);
} else if (listItems.get(position).getAttendance().equals("absent")) {
radioAttendanceAbsent.setChecked(true);
}
} else {
radioAttendance.clearCheck();
}
name.setText(listItems.get(position).getName());
roll.setText(listItems.get(position).getRoll());
previous.setText(listItems.get(position).getPreviousAttendance());
}
}
Notice that we have separate click listener for each radio button and set the state in the list of items and just check that state when we are binding, also we have removed the onCheckChangedListener and the sparse boolean array, one last thing is that we made sure that when there is not state set for the attendance property, we just clear the radio buttons so that no one is selected the code is much simpler and works correctly now.

You have to initialize your RadioButton based on model state like below:
#Override
public void onBindViewHolder (final AttendanceAdapter.ViewHolder holder, final int position) {
final AttendanceModel listItem = listItemsFiltered.get(position);
holder.name.setText(listItem.getName());
holder.roll.setText(listItem.getRoll());
holder.previous.setText(listItem.getPreviousAttendance());
final String id =listItem.getId();
final String class_id =listItem.getClassId();
holder.radioAttendance.setOnCheckedChangeListener(null);
if(listItem.getAttendance().equalsIgnoreCase("present")) {
radioAttendancePresent.setChecked(true);
} else {
radioAttendancePresent.setChecked(false);
}
//Add listener here and remove from holder
holder.radioAttendance.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
#Override
public void onCheckedChanged(RadioGroup radioGroup, int i) {
if(holder.radioAttendancePresent.isChecked()) {
listItemsFiltered.get(position).setAttendance("present");
} else {
listItemsFiltered.get(position).setAttendance("absent");
}
notifyDataSetChanged();
}
});
}

Filter an Object in BaseAdapter

I'm new in Android programming and I want to create a custom Filter in my Baseadapter.
Honestly it's kinda confusing when I check the other questions because they mostly use Arraylists. I already created a custom View (getView) that sets small pictogramms into my ListView. I already tried many ways to implement these custom Filter from Arraylist examples, but somehow I get into a blockade.
It would be very helpful if someone could atleast give me some direction for a Custom Filter with Objects
cryptoListAdapter.java
public class cryptoListAdapter extends BaseAdapter {
private Context context;
LayoutInflater mInlfater;
ArrayList<HashMap<String,String>> currencyList;
TextView name;
// Constructor
public cryptoListAdapter(Context context,ArrayList<HashMap<String,String>> currencyList)
{
mInlfater = LayoutInflater.from(context);
this.currencyList = currencyList;
}
#Override
public int getCount() {
return currencyList.size();
}
#Override
public Object getItem(int position) {
// TODO Auto-generated method stub
return position;
}
#Override
public long getItemId(int position) {
// TODO Auto-generated method stub
return position;
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
cryptoPicto cp = new cryptoPicto();
View newView = LayoutInflater.from(parent.getContext()).inflate(R.layout.list_crypto_items, null);
name = (TextView) newView.findViewById(R.id.name);
TextView symbol = (TextView) newView.findViewById(R.id.symbol);
ImageView image_list_icon = (ImageView)newView.findViewById(cryptopicto);
//cp.createFinalFileName(name);
HashMap<String, String> map;
map = currencyList.get(position);
name.setText(map.get("name"));
symbol.setText(map.get("symbol"));
Picasso.with(newView.getContext()).load(map.get("cryptopicto")).into(image_list_icon);
return newView;
}
currencyTableView.java
public class currencyTableView extends AppCompatActivity {
private String TAG = currencyTableView.class.getSimpleName();
private ProgressDialog pDialog;
private ListView lv;
private SearchView sv;
private ImageView im;
private static String url = "https//myURLToJSON";
Context context;
cryptoListAdapter adapter;
ArrayList<HashMap<String, String>> currencyList;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_currency_table_view);
sv = (SearchView) findViewById(R.id.search_currency);
currencyList = new ArrayList<>();
lv = (ListView) findViewById(R.id.list);
im = (ImageView) findViewById(R.id.cryptopicto);
new GetCurrencies().execute();
}
// URL to get currencies JSON
private class GetCurrencies extends AsyncTask<Void, Void, Void> {
#Override
protected void onPreExecute() {
super.onPreExecute();
// Showing progress dialog
pDialog = new ProgressDialog(currencyTableView.this);
pDialog.setMessage("Please wait...");
pDialog.setCancelable(false);
pDialog.show();
}
#Override
protected Void doInBackground(Void... arg0) {
databasehandler sh = new databasehandler();
cryptoPicto cp = new cryptoPicto();
// Making a request to url and getting response
String jsonStr = sh.makeServiceCall(url);
Log.e(TAG, "Response from url: " + jsonStr);
if (jsonStr != null) {
try {
JSONArray jsonArray = new JSONArray(jsonStr);
// looping through currencies
for (int i = 0; i < jsonArray.length(); i++) {
JSONObject c = jsonArray.getJSONObject(i);
String name = c.getString("name");
String symbol = c.getString("symbol");
Double price_usd = c.getDouble("price_usd");
Double price_eur = c.getDouble("price_eur");
Double price_btc = c.getDouble("price_btc");
Double volume_eur = c.getDouble("volume_eur");
Double market_cap_usd = c.getDouble("market_cap_usd");
Double percent_change_1h = c.getDouble("percent_change_1h");
Double percent_change_24h = c.getDouble("percent_change_24h");
Double percent_change_7d = c.getDouble("percent_change_7d");
// tmp hash map for single currency
HashMap<String, String> currency = new HashMap<>();
// create Path to picto Filename
cp.createFinalFileName(name);
// adding each child node to HashMap key => value
currency.put("cryptopicto", cp.getFinalFileName());
currency.put("name", name);
currency.put("symbol", symbol);
// adding currency to currencyList
currencyList.add(currency);
}
} catch (final JSONException e) {
Log.e(TAG, "Json parsing error: " + e.getMessage());
runOnUiThread(new Runnable() {
#Override
public void run() {
Toast.makeText(getApplicationContext(),
"Json parsing error: " + e.getMessage(),
Toast.LENGTH_LONG)
.show();
}
});
}
} else {
Log.e(TAG, "Couldn't get json from server.");
runOnUiThread(new Runnable() {
#Override
public void run() {
Toast.makeText(getApplicationContext(),
"Couldn't get json from server. Check LogCat for possible errors!",
Toast.LENGTH_LONG)
.show();
}
});
}
return null;
}
#Override
protected void onPostExecute(Void result) {
super.onPostExecute(result);
// Dismiss the progress dialog
if (pDialog.isShowing())
pDialog.dismiss();
/**
* Updating parsed JSON data into ListView
* */
adapter = new cryptoListAdapter(
currencyTableView.this, currencyList) {
};
lv.setAdapter(adapter);
sv.setOnQueryTextListener(new SearchView.OnQueryTextListener() {
#Override
public boolean onQueryTextSubmit(String query) {
return false;
}
#Override
public boolean onQueryTextChange(String currencyList) {
adapter.getFilter().filter(currencyList);
return false;
}
});
}
}
}
Thanks in Advance :)

Make your BaseAdapder implements Filterable
then add
List<HashMap<String,String>> mOriginalValues;
after
ArrayList<HashMap<String,String>> currencyList;
in your adapter class
and then add this method at the bottom before the closing braces "}"
#Override
public Filter getFilter() {
Filter filter = new Filter() {
#SuppressWarnings("unchecked")
#Override
protected void publishResults(CharSequence constraint, FilterResults results) {
currencyList = (ArrayList<HashMap<String,String>>) results.values;
notifyDataSetChanged();
}
#Override
protected FilterResults performFiltering(CharSequence constraint) {
FilterResults results = new FilterResults();
ArrayList<HashMap<String, String>> FilteredArrList = new ArrayList<HashMap<String, String>>();
if (mOriginalValues == null) {
mOriginalValues = new ArrayList<HashMap<String, String>>(currencyList); // saves
}
if (constraint == null || constraint.length() == 0) {
// set the Original result to return
results.count = mOriginalValues.size();
results.values = mOriginalValues;
} else {
Locale locale = Locale.getDefault();
constraint = constraint.toString().toLowerCase(locale);
for (int i = 0; i < mOriginalValues.size(); i++) {
HashMap<String, String> currency = mOriginalValues.get(i);
String data = currency.get("name");
if (data.toLowerCase(locale).startsWith(constraint.toString())) {
FilteredArrList.add(currency);
}
}
// set the Filtered result to return
results.count = FilteredArrList.size();
results.values = FilteredArrList;
}
return results;
}
};
return filter;
}
Let me know if that helps

Android studio, loading 2 spinners with different data from different MYSQL databases

My app has an itinerary function, the part where you create a new itinerary involves selecting from 2 spinners which drop down to present different options. The data coming from MQsql database and the JSON response is correct for both sets. Currently i have been able to get either one set of the data to load in the correct spinner (being which either just transport info or attraction info but not both), or i have been able to get both sets of data to load but both are displayed in the same 2 spinners. I need them to be separated into there allocated spinners but need help doing this as i dont undertand what im doing wrong.
createItinerary class:
public class CreateItinerary extends AppCompatActivity implements AdapterView.OnItemSelectedListener {
TextView txtDate;
private Spinner spinnerAttraction;
private Spinner spinnerTransport;
// array list for spinner adapter
private ArrayList<Category> categoriesList;
ProgressDialog pDialog;
List<String> lables = new ArrayList<String>();
private ArrayList<ItineraryAdapter>Entities;
private ArrayList<ItineraryAdapter>finalEntities;
LayoutInflater myInflator;
View myView;
DBManager db;
myAdapter adapter;
String NAME;
String LOCATION;
String TIME;
static final int DIALOG_ID = 0;
int hour_x;
int min_x;
TextView TextTime;
String ItineraryName;
private String URL_ATTRACTIONS = "http://10.0.2.2/TravelApp/get_all_spinner.php";
private String URL_TRANSPORT = "http://10.0.2.2/TravelApp/get_all_transport_minor.php";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_create_itinerary);
txtDate = (TextView) findViewById(R.id.tvSelectDate);
myInflator = getLayoutInflater();
myView = myInflator.inflate(R.layout.list_create_itinerary, null);
spinnerAttraction = (Spinner) findViewById(R.id.spinnerAttraction);
spinnerTransport = (Spinner) findViewById(R.id.spinnerTransport);
db = new DBManager(this);
categoriesList = new ArrayList<Category>();
Entities = new ArrayList<ItineraryAdapter>();
finalEntities = new ArrayList<ItineraryAdapter>();
// spinner item select listener
spinnerAttraction.setOnItemSelectedListener(this);
spinnerTransport.setOnItemSelectedListener(this);
new GetAttractions().execute();
new GetTransport().execute();
showTimePickerDialog();
Bundle bundle = getIntent().getExtras();
ItineraryName = bundle.getString("Itinerary Name");
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.home_button, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if(id == R.id.go_home){
final TextView alertMessage = new TextView(this);
alertMessage.setText(" All changes will be lost are you sure you want to return back to the home page? ");
AlertDialog dialog = new AlertDialog.Builder(this)
.setTitle("Unsaved changes")
.setView(alertMessage)
.setPositiveButton("Yes", new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialog, int which) {
Intent i = new Intent(getApplicationContext(), QavelNav.class);
startActivity(i);
}
})
.setNegativeButton("No", null)
.create();
dialog.show();
}
return super.onOptionsItemSelected(item);
}
public void pickDate(View v) {
DatePickerClass datepicker = new DatePickerClass();
datepicker.setText(v);
datepicker.show(getSupportFragmentManager(), "datepicker");
System.out.println(getDate());
}
public String getDate() {
String date;
date = txtDate.getText().toString();
return date;
}
public void addAttractionToItinerary(View v){
Entities.add(new ItineraryAdapter(NAME,LOCATION,null));
loadAttractions();
System.out.println(ItineraryName);
}
public void loadAttractions(){
adapter = new myAdapter(Entities);
ListView ls = (ListView) findViewById(R.id.listCreateItinerary);
ls.setAdapter(adapter);
for(int i =0; i < finalEntities.size(); i++){
System.out.println(finalEntities.get(i).NAME + " " + finalEntities.get(i).LOCATION + " " + finalEntities.get(i).TIME);
}
}
public void onSave(View v){
ContentValues values = new ContentValues();
for(int i = 0; i <finalEntities.size();i++) {
values.put(DBManager.ColItineraryName,ItineraryName);
values.put(DBManager.ColDate,txtDate.getText().toString());
values.put(DBManager.ColName,finalEntities.get(i).NAME );
values.put(DBManager.ColLocation,finalEntities.get(i).LOCATION);
values.put(DBManager.ColTime,finalEntities.get(i).TIME);
long id = db.Insert("Itinerary",values);
if (id > 0)
Toast.makeText(getApplicationContext(),"Added to Itinerary", Toast.LENGTH_LONG).show();
else
Toast.makeText(getApplicationContext(),"cannot insert", Toast.LENGTH_LONG).show();
}
}
public void showTimePickerDialog(){
TextTime = (TextView) myView.findViewById(R.id.tvCreateItineraryTime);
TextTime.setOnClickListener(new View.OnClickListener(){
#Override
public void onClick(View v){
showDialog(DIALOG_ID);
}
});
}
#Override
protected Dialog onCreateDialog(int id){
if(id== DIALOG_ID)
return new TimePickerDialog(CreateItinerary.this,KTimePickerListner, hour_x, min_x,false);
return null;
}
protected TimePickerDialog.OnTimeSetListener KTimePickerListner = new TimePickerDialog.OnTimeSetListener(){
#Override
public void onTimeSet(TimePicker view, int hourOfDay, int minute){
hour_x = hourOfDay;
min_x = minute;
Toast.makeText(CreateItinerary.this,hour_x+" : " + min_x, Toast.LENGTH_LONG).show();
setTime(hour_x, min_x);
TIME = hour_x + ":" + min_x;
finalEntities.add(new ItineraryAdapter(NAME,LOCATION,TIME));
}
};
public void setTime(int hour, int min){
TextTime.setText(hour_x+":"+min_x);
}
#Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long l) {
Toast.makeText(
getApplicationContext(),
parent.getItemAtPosition(position).toString() + " Selected" ,
Toast.LENGTH_LONG).show();
NAME = categoriesList.get(position).getName();
LOCATION = categoriesList.get(position).getLocation();
}
#Override
public void onNothingSelected(AdapterView<?> adapterView) {
}
/**
* Adding spinner data
* */
private void populateSpinner() {
for (int i = 0; i < categoriesList.size(); i++) {
lables.add(categoriesList.get(i).getName() + " - " + categoriesList.get(i).getLocation());
}
// Creating adapter for spinner
ArrayAdapter<String> spinnerAdapter = new ArrayAdapter<String>(this,
android.R.layout.simple_spinner_item, lables);
// Drop down layout style - list view with radio button
spinnerAdapter
.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
// attaching data adapter to spinner
spinnerAttraction.setAdapter(spinnerAdapter);
spinnerTransport.setAdapter(spinnerAdapter);
}
/**
* Async task to get all food categories
* */
private class GetAttractions extends AsyncTask<Void, Void, Void> {
#Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = new ProgressDialog(CreateItinerary.this);
pDialog.setMessage("Fetching attraction categories..");
pDialog.setCancelable(false);
pDialog.show();
}
#Override
protected Void doInBackground(Void... arg0) {
ServiceHandler jsonParser = new ServiceHandler();
String json = jsonParser.makeServiceCall(URL_ATTRACTIONS, ServiceHandler.GET);
Log.e("Response: ", "> " + json);
if (json != null) {
try {
JSONObject jsonObj = new JSONObject(json);
if (jsonObj != null) {
JSONArray categories = jsonObj
.getJSONArray("attraction");
for (int i = 0; i < categories.length(); i++) {
JSONObject catObj = (JSONObject) categories.get(i);
Category cat = new Category(catObj.getInt("Id"),
catObj.getString("Name"), catObj.getString("Location"));
categoriesList.add(cat);
}
}
} catch (JSONException e) {
e.printStackTrace();
}
} else {
Log.e("JSON Data", "Didn't receive any data from server!");
}
return null;
}
#Override
protected void onPostExecute(Void result) {
super.onPostExecute(result);
if (pDialog.isShowing())
pDialog.dismiss();
populateSpinner();
}
}
private class GetTransport extends AsyncTask<Void, Void, Void> {
#Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = new ProgressDialog(CreateItinerary.this);
pDialog.setMessage("Fetching transport categories..");
pDialog.setCancelable(false);
pDialog.show();
}
#Override
protected Void doInBackground(Void... arg0) {
ServiceHandler jsonParser = new ServiceHandler();
String json = jsonParser.makeServiceCall(URL_TRANSPORT, ServiceHandler.GET);
Log.e("Response: ", "> " + json);
if (json != null) {
try {
JSONObject jsonObj = new JSONObject(json);
if (jsonObj != null) {
JSONArray categories = jsonObj
.getJSONArray("transport");
for (int i = 0; i < categories.length(); i++) {
JSONObject catObj = (JSONObject) categories.get(i);
Category cat = new Category(catObj.getInt("Id"),
catObj.getString("Name"), catObj.getString("Location"));
categoriesList.add(cat);
}
}
} catch (JSONException e) {
e.printStackTrace();
}
} else {
Log.e("JSON Data", "Didn't receive any data from server!");
}
return null;
}
#Override
protected void onPostExecute(Void result) {
super.onPostExecute(result);
if (pDialog.isShowing())
pDialog.dismiss();
populateSpinner();
}
}
class myAdapter extends BaseAdapter {
public ArrayList<ItineraryAdapter> listItem;
ItineraryAdapter ac;
public myAdapter(ArrayList<ItineraryAdapter> listItem) {
this.listItem = listItem;
}
#Override
public int getCount() {
return listItem.size();
}
#Override
public Object getItem(int position) {
return null;
}
#Override
public long getItemId(int position) {
return position;
}
#Override
public View getView(final int position, View view, ViewGroup viewGroup) {
ac = listItem.get(position);
TextView Name = (TextView) myView.findViewById(R.id.tvCreateItineraryName);
Name.setText(ac.NAME);
TextView Location = (TextView) myView.findViewById(R.id.tvCreateItineraryLocation);
Location.setText(ac.LOCATION);
/*
Button buttonDelete = (Button)myView.findViewById(R.id.buttonDelete);
buttonDelete.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Entities.remove(position);
finalEntities.remove(position);
loadAttractions();
}
});*/
return myView;
}
}
}
Thank you to anyone who can help me with this.

Java Android ListView add item

I want to implement Load-More feature in my ListView.
Here is my code:
public class MainActivity extends Activity {
int url_page = 0;
private static String URL = "http://MyURL&page_no=";
ArrayList<ItemInfo> products = new ArrayList<ItemInfo>();
BoxAdapter boxAdapter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
new AsyncTaskParseJson().execute();
}
public class AsyncTaskParseJson extends AsyncTask<String, String, String> {
final String TAG = "AsyncTaskParseJson.java";
JSONArray dataJsonArr = null;
#Override
protected void onPreExecute() {}
#Override
protected String doInBackground(String... arg0) {
try {
JsonParser jParser = new JsonParser();
JSONObject json = jParser.getJSONFromUrl(URL+"0");
dataJsonArr = json.getJSONArray("data");
for (int i = 0; i < dataJsonArr.length(); i++) {
JSONObject c = dataJsonArr.getJSONObject(i);
String nickname = c.getString("nickname");
String description = c.getString("description");
products.add(new ItemInfo(nickname, description));
}
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
#Override
protected void onPostExecute(String strFromDoInBg)
{
SetAdapter();
}
}
public void SetAdapter()
{
boxAdapter = new BoxAdapter(this, products);
ListView lvMain = (ListView) findViewById(R.id.list);
lvMain.setOnItemClickListener(new OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id)
{
ListView lvMain = (ListView) findViewById(R.id.list);
int pos = lvMain.getPositionForView(view);
ItemInfo p = boxAdapter.getItem(pos);
//
String username = p.username;
String description = p.description;
// Starting single contact activity
Intent in = new Intent(getApplicationContext(),
OnClickActivity.class);
in.putExtra("username", username);
in.putExtra("description", description);
startActivity(in);
}
});
lvMain.setAdapter(boxAdapter);
lvMain.setOnScrollListener(new OnScrollListener()
{
#Override
public void onScroll(AbsListView view, int firstVisibleItem,
int visibleItemCount, int totalItemCount) {
// TODO Auto-generated method stub
ListView lvMain = (ListView) findViewById(R.id.list);
if(firstVisibleItem + visibleItemCount >= totalItemCount) {
boxAdapter.loadAdditionalItems();
}
}
#Override
public void onScrollStateChanged(AbsListView view, int scrollState) {
// TODO Auto-generated method stub
}
});
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}
I added this to onScroll event:
if (lvMain.getLastVisiblePosition() >= lvMain.getCount())
{
url_page = url_page + 1;
new LoadLastestPost().execute();
}
And asyntask:
public class LoadLastestPost extends AsyncTask<String, String, String> {
final String TAG = "LoadLastestPost.java";
JSONArray dataJsonArr = null;
#Override
protected void onPreExecute() {}
#Override
protected String doInBackground(String... arg0) {
try {
JsonParser jParser = new JsonParser();
String newURL = URL + String.valueOf(url_page);
JSONObject json = jParser.getJSONFromUrl(newURL);
dataJsonArr = json.getJSONArray("data");
for (int i = 0; i < dataJsonArr.length(); i++) {
JSONObject c = dataJsonArr.getJSONObject(i);
String nickname = c.getString("nickname");
String description = c.getString("description");
products.add(new ItemInfo(nickname, description));
}
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
#Override
protected void onPostExecute(String strFromDoInBg)
{
LoadMoreItem();
}
}
private void LoadMoreItem()
{
ListView lvMain = (ListView) findViewById(R.id.list);
boxAdapter = null;
boxAdapter = new BoxAdapter(this, products);
lvMain.setAdapter(boxAdapter);
boxAdapter.notifyDataSetChanged();
}
But it is not working ;( That needs fixing?
P.S i display 10 item, and load more 10 response of an already loaded.
I want load items in the end of listview.