How to load data(json) into recycler view using volley - json

Question

I have implemented recyclerview in my application and now i need to fetch data from the server and i just came to know about volley being the best way to fetch data. I searched online but i am unable to find a proper tutorial for the same.
This is how i initialized the recyclerview in my code.(which has hardcoded data set)
mRecyclerView = (RecyclerView) findViewById(R.id.recyclerview);
LinearLayoutManager linearLayoutManager = new LinearLayoutManager(this);
linearLayoutManager.setOrientation(LinearLayoutManager.VERTICAL);
mRecyclerView.setLayoutManager(linearLayoutManager);
mAdapter = new CardAdapter();
mRecyclerView.setAdapter(mAdapter);
here is the adapter code.
public class CardAdapter extends RecyclerView.Adapter<CardAdapter.ViewHolder> {
ArrayList<BusRouteNameDetails> mItems;
public int TAG=0;
public CardAdapter() {
super();
mItems = new ArrayList<>();
BusRouteNameDetails routename = new BusRouteNameDetails();
routename.setName("xyz");
routename.setNumber("X4");
mItems.add(routename);
routename = new BusRouteNameDetails();
routename.setName("xyz");
routename.setNumber("X4");
mItems.add(routename);
routename = new BusRouteNameDetails();
routename.setName("xyz");
routename.setNumber("X4");
mItems.add(routename);
routename = new BusRouteNameDetails();
routename.setName("xyz");
routename.setNumber("X4");
mItems.add(routename);
routename = new BusRouteNameDetails();
routename.setName("xyz");
routename.setNumber("X4");
mItems.add(routename);
}
#Override
public ViewHolder onCreateViewHolder(ViewGroup viewGroup, int i) {
View v = LayoutInflater.from(viewGroup.getContext())
.inflate(R.layout.busroutename_list, viewGroup, false);
ViewHolder viewHolder = new ViewHolder(v);
return viewHolder;
}
#Override
public void onBindViewHolder(ViewHolder viewHolder, int i) {
BusRouteNameDetails routename = mItems.get(i);
viewHolder.tvName.setText(routename.getName());
viewHolder.tvRoutename.setText(routename.getNumber());
Log.e("TAG","i value="+ i);
if(i==mItems.size()-1)
viewHolder.seperator.setVisibility(View.INVISIBLE);
}
#Override
public int getItemCount() {
Log.e("TAG","item size"+ mItems.size());
return mItems.size();
}
class ViewHolder extends RecyclerView.ViewHolder{
public TextView tvName;
public TextView tvRoutename;
public View seperator;
public ViewHolder(View itemView) {
super(itemView);
tvName = (TextView)itemView.findViewById(R.id.RouteName1);
tvRoutename = (TextView)itemView.findViewById(R.id.Route_src_dest);
seperator=(View)itemView.findViewById(R.id.seperator);
}
}
}
And here are the getters and setters
public class BusRouteNameDetails {
private String mName;
private String mNumber;
public String getName() {
return mName;
}
public void setName(String name) {
this.mName = name;
}
public String getNumber() {
return mNumber;
}
public void setNumber(String Number) {
this.mNumber = Number;
}
}

Answer 1

You can try as my following solution:
Let's assume the server response as the following JSON:
[
{
"name": "Person 1",
"age": 30
},
{
"name": "Person 2",
"age": 20
},
{
"name": "Person 3",
"age": 40
}
]
In your Android project:
public class Person {
String name;
Integer age;
Person() {
}
}
public class RVAdapter extends RecyclerView.Adapter<RVAdapter.PersonViewHolder> {
List<Person> persons;
RVAdapter(List<Person> persons) {
this.persons = persons;
}
#Override
public PersonViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.cardview, parent, false);
PersonViewHolder pvh = new PersonViewHolder(v);
return pvh;
}
#Override
public void onBindViewHolder(PersonViewHolder holder, int position) {
holder.personName.setText(persons.get(position).name);
holder.personAge.setText(String.valueOf(persons.get(position).age));
}
#Override
public int getItemCount() {
if (persons != null) {
return persons.size();
}
return 0;
}
#Override
public void onAttachedToRecyclerView(RecyclerView recyclerView) {
super.onAttachedToRecyclerView(recyclerView);
}
public static class PersonViewHolder extends RecyclerView.ViewHolder {
CardView cv;
TextView personName;
TextView personAge;
PersonViewHolder(View itemView) {
super(itemView);
cv = (CardView) itemView.findViewById(R.id.cv);
personName = (TextView) itemView.findViewById(R.id.person_name);
personAge = (TextView) itemView.findViewById(R.id.person_age);
}
}
}
Then in your Activity:
...
RecyclerView rv = (RecyclerView)findViewById(R.id.rv);
rv.setHasFixedSize(true);
LinearLayoutManager llm = new LinearLayoutManager(mContext);
rv.setLayoutManager(llm);
final RVAdapter rvAdapter = new RVAdapter(personList);
rv.setAdapter(rvAdapter);
RequestQueue requestQueue = Volley.newRequestQueue(mContext);
String url = "http://192.16.1.100/api/persons";
JsonArrayRequest jsonArrayRequest = new JsonArrayRequest(url, new Response.Listener<JSONArray>() {
#Override
public void onResponse(JSONArray response) {
try {
if (response.length() > 0) {
personList.clear();
for (int i = 0; i < response.length(); i++) {
JSONObject jsonObject = response.getJSONObject(i);
Person person = new Person();
if (!jsonObject.isNull("name")) {
person.name = jsonObject.getString("name");
}
if (!jsonObject.isNull("age")) {
person.age = jsonObject.getInt("age");
}
personList.add(i, person);
}
rvAdapter.notifyDataSetChanged();
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}, new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
// do something
}
});
requestQueue.add(jsonArrayRequest);
...
Here is the result
Hope this helps!