Develop Reference

How parse JSON data into ListView

I would like to visualize the Json data on a listview, but I don't know how to do it ... I tried to use a TextView to verify the correct passage of the data and it seems to work, but I would need to display them on the listView ... ideas?
{"Esito":true,"Dati":[{"id":"357","id_utente":"16","nome_prodotto":"cozze"},{"id":"358","id_utente":"16","nome_prodotto":"riso"},{"id":"362","id_utente":"16","nome_prodotto":"patate"},{"id":"366","id_utente":"16","nome_prodotto":"cozze"},{"id":"367","id_utente":"16","nome_prodotto":null}]}
JsonObjectRequest request = new JsonObjectRequest(Request.Method.G[enter image description here][1]ET, url, null,
new Response.Listener<JSONObject>() {
#Override
public void onResponse(JSONObject response) {
try {
JSONArray jsonArray = response.getJSONArray("Dati");
for (int i = 0; i < jsonArray.length(); i++) {
JSONObject dato = jsonArray.getJSONObject(i);
String id = dato.getString("id");
String id_utente = dato.getString("id_utente");
String nome_prodotto = dato.getString("nome_prodotto");
mTextViewResult.append(id + ", " + id_utente + ", " + nome_prodotto + "\n\n");
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}

Just make new object class and collect data to list :
class YourObiekt {
private String id;
private String idUtente;
private String nomeProdotto;
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getIdUtente() {
return idUtente;
}
public void setIdUtente(String idUtente) {
this.idUtente = idUtente;
}
public String getNomeProdotto() {
return nomeProdotto;
}
public void setNomeProdotto(String nomeProdotto) {
this.nomeProdotto = nomeProdotto;
}
}
List<YourObiekt> yourObiektList = new ArrayList<YourObiekt>();
JsonObjectRequest request = new JsonObjectRequest(Request.Method.GET, url, null,
new Response.Listener<JSONObject>() {
#Override
public void onResponse(JSONObject response) {
try {
JSONArray jsonArray = response.getJSONArray("Dati");
for (int i = 0; i < jsonArray.length(); i++) {
JSONObject dato = jsonArray.getJSONObject(i);
YourObiekt yo = new YourObiekt();
yo.setId(dato.getString("id"));
yo.setIdUtente(dato.getString("id_utente"));
yo.setNomeProdotto(dato.getString("nome_prodotto"));
yourObiektList.add(yo);
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}
And now you get yourObiektList as data for your listView

android org.json.JSONArray cannot be converted to JSONObject (can not display the url)

I am new in android I work on a webservice application and the backend in laravel ,I want to read the trades and according to the job I find the tasks but I can not display the data it shows me this error msg ..
"org.json.JSONArray cannot be converted to JSONObject"
public static final String TacheNamearray = "libelle_tache";
public static final String TacheName = "libelle_tache";
public static final String JSON_ARRAY_TACHE = "result";
public static final String MetierNamearray = "libelle_metier";
public static final String MetierName = "libelle_metier";
public static final String JSON_ARRAY = "result";
private JSONArray result;
private ArrayList<String> arrayListTache;
TextView tacheename;
Spinner spinner_tache;
Spinner spinner;
Button button;
private GpsTracker gpsTracker;
private TextView tvLatitude,tvLongitude;
String URL_Post = "http://192.168.1.233/projet/public/api/getmetier";
private ArrayList<String> arrayList;
TextView employeename;
private TextView tvUsername, tvEmail;
private UserInfo userInfo;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_recherche);
spinner= (Spinner) findViewById(R.id.spnrEmployee);
spinner_tache= (Spinner) findViewById(R.id.spnrTache);
tacheename= (TextView) findViewById(R.id.tvTache);
employeename= (TextView) findViewById(R.id.tvName);
button = (Button) findViewById(R.id.button);
tvLatitude = (TextView)findViewById(R.id.latitude);
tvLongitude = (TextView)findViewById(R.id.longitude);
arrayListTache = new ArrayList<String>();
userInfo = new UserInfo(this);
tvEmail = (TextView)findViewById(R.id.key_email);
String email = userInfo.getKeyEmail();
tvEmail.setText(email);
arrayList = new ArrayList<String>();
getMetiers();
spinner.setOnItemSelectedListener(new
AdapterView.OnItemSelectedListener() {
#Override
public void onItemSelected(AdapterView<?> parent, View view, int
position, long id) {
//Setting the values to textviews for a selected item
String metier= arrayList.get(position);
getTaches(metier);
}
#Override
public void onNothingSelected(AdapterView<?> parent) {
employeename.setText("");
}
});
}
private void getMetiers() {
StringRequest stringRequest = new
StringRequest("http://192.168.1.233/projet/public/api/getmetier",
new Response.Listener<String>() {
#Override
public void onResponse(String response) {
JSONObject j = null;
try {
j = new JSONObject(response);
result = j.getJSONArray(JSON_ARRAY);
empdetails(result);
} catch (JSONException e) {
e.printStackTrace();
}
}
},
new ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
}
});
RequestQueue requestQueue = Volley.newRequestQueue(this);
requestQueue.add(stringRequest);
}
private void empdetails(JSONArray j) {
for (int i = 0; i < j.length(); i++) {
try {
JSONObject json = j.getJSONObject(i);
arrayList.add(json.getString(MetierNamearray));
} catch (JSONException e) {
e.printStackTrace();
}
}
// arrayList.add(0,"Select Employee");
spinner.setAdapter(new ArrayAdapter<String>(RechercheActivity.this,
android.R.layout.simple_spinner_dropdown_item, arrayList));
}
//Method to get student name of a particular position
private String getemployeeName(int position){
String name="";
try {
//Getting object of given index
JSONObject json = result.getJSONObject(position);
//Fetching name from that object
name = json.getString(MetierName);
} catch (JSONException e) {
e.printStackTrace();
}
//Returning the name
return name;
}
public void getLocation(View view){
gpsTracker = new GpsTracker(RechercheActivity.this);
insert();
if(gpsTracker.canGetLocation()){
double latitude = gpsTracker.getLatitude();
double longitude = gpsTracker.getLongitude();
tvLatitude.setText(String.valueOf(latitude));
tvLongitude.setText(String.valueOf(longitude));
}else{
gpsTracker.showSettingsAlert();
}
Intent intent = new Intent(RechercheActivity.this,
TechnicienActivity.class);
startActivity(intent);
}
public void insert(){
StringRequest stringRequest = new StringRequest(Request.Method.POST,
URL_Post, new Response.Listener<String>() {
#Override
public void onResponse(String response) {
Toast.makeText(getApplication(),response,Toast.LENGTH_LONG).show();
}
}, new ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
Toast.makeText(RechercheActivity.this,error+"",Toast.LENGTH_LONG).show();
}
}
){
#Override
protected Map<String,String>getParams()throws AuthFailureError {
Map<String,String> params = new HashMap<String,String>();
String text1 = spinner.getSelectedItem().toString();
String lon = tvLongitude.getText().toString().trim();
String lat = tvLatitude.getText().toString().trim();
params.put("libelle_metier",text1);
return params;
}
};
RequestQueue requestQueue = Volley.newRequestQueue(this);
requestQueue.add(stringRequest);
}
private void getTaches(String metier) {
StringRequest stringRequest = new
StringRequest("http://192.168.1.233/projet/public/api/gettaches",
new Response.Listener<String>() {
#Override
public void onResponse(String response) {
JSONObject j = null;
try {
j = new JSONObject(response);
result= j.getJSONArray(JSON_ARRAY_TACHE);
tachedetails(result);
} catch (JSONException e) {
e.printStackTrace();
}
}
},
new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
}
});
RequestQueue requestQueue = Volley.newRequestQueue(this);
requestQueue.add(stringRequest);
}
private void tachedetails(JSONArray j) {
for (int i = 0; i < j.length(); i++) {
try {
JSONObject json = j.getJSONObject(i);
arrayListTache.add(json.getString(TacheNamearray));
} catch (JSONException e) {
e.printStackTrace();
}
// arrayListTache.add(0,"Select Employee");
spinner_tache.setAdapter(new ArrayAdapter<String>
(RechercheActivity.this,
android.R.layout.simple_spinner_dropdown_item, arrayListTache));
}
//Method to get student name of a particular position
private String gettacheName(int position){
String libelle_tache="";
try {
//Getting object of given index
JSONObject json = result.getJSONObject(position);
//Fetching name from that object
libelle_tache = json.getString(TacheName);
} catch (JSONException e) {
e.printStackTrace();
}
//Returning the name
return libelle_tache;
}
and the JSON part gives me that ..
[{"id":1,"libelle_metier":"metier 1","deleted_at":null,"created_at":"2018-04-03 09:12:37","updated_at":"2018-04-03 09:12:37"},{"id":2,"libelle_metier":"metier 2","deleted_at":null,"created_at":"2018-04-03 09:12:44","updated_at":"2018-04-03 09:12:44"},{"id":3,"libelle_metier":"metier 4","deleted_at":null,"created_at":"2018-04-03 09:46:36","updated_at":"2018-04-04 14:15:06"}]
and my PHP code and
class TechniciensController extends Controller
{
public function GetTechniciens()
{
return Technicien::all();
}

return json_encode(Technicien::all());
then you can use json_decode.
this line :
j = new JSONObject(response);
update it:
JSONArray jsonarray = new JSONArray(response);
i think it's works.

My app crashes when there is no value in my JSON

I'm posting "id" value (which i pass to this activity via getintent)
Uid = getIntent().getStringExtra("id");
to server and retrieving the corresponding jsonobjects.
#Override
protected Map<String, String> getParams() {
Map<String, String> params = new HashMap<String, String>();
params.put("id", Uid);
return params;
}
When my jsonarray is empty, my app crashes. I want to toast"Error" when jsonarray is empty. How can I fix this?
Here is my code:
public class kill extends FragmentActivity {
GridView grid1;
CustomGrid_Album adapter;
private ProgressDialog pDialog;
String Uid,Disp;
public String category;
public String selected;
public static String imagename;
Button Alb_sel;
ArrayList<Item_album> gridArray = new ArrayList<Item_album>();
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.album_display);
grid1 = (GridView) findViewById(R.id.gridView2);
Uid = getIntent().getStringExtra("id");
Disp = getIntent().getStringExtra("disp");
Alb_sel=(Button)findViewById(R.id.album_to_select);
pDialog = new ProgressDialog(kill.this);
pDialog.setMessage("Loading...");
pDialog.show();
//fetching JSONArray
final RequestQueue queue = Volley.newRequestQueue(getApplicationContext());
StringRequest stringRequest = new StringRequest(com.android.volley.Request.Method.POST, AppConfig.URL_Gallery4,
new Response.Listener<String>() {
#Override
public void onResponse(String response) {
Datas.imageIds = new String[response.length()];
JSONArray arr = null;
try {
arr = new JSONArray(response);
} catch (JSONException e1) {
e1.printStackTrace();
}
int i=0;
for (i = 0; i < arr.length(); i++) {
try {
JSONObject obj = arr.getJSONObject(i);
category = obj.getString("category_name");
selected = obj.getString("album_id");
imagename = obj.getString("org_image_name");
Datas.imageIds[i] = AppConfig.URL_IMAGE_temp+obj.getString("album_image").substring(3);
gridArray.add(new Item_album(Datas.imageIds[i]));
} catch (JSONException e) {
e.printStackTrace();
}
}
final int xl = i;
adapter = new CustomGrid_Album(kill.this,xl,gridArray);
adapter.notifyDataSetChanged();
grid1.setAdapter(adapter);
pDialog.dismiss();
}
}, new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
Toast.makeText(getApplicationContext(), "No images in this gallery", Toast.LENGTH_SHORT).show();
error.printStackTrace();
}
})
{
#Override
protected Map<String, String> getParams() {
Map<String, String> params = new HashMap<String, String>();
params.put("id", Uid);
return params;
}
};
queue.add(stringRequest);
}
}

apply the check in onResponse
if(response.length()==0){
// error message
}else{
// your rest of the code
}

This looks problematic.
Datas.imageIds = new String[response.length()];
You don't want an array with the size of the string. You want an array of the size of the JSONArray within the response.
public void onResponse(String response) {
JSONArray arr = null;
try {
arr = new JSONArray(response);
Datas.imageIds = new String[arr.length()];
} catch (JSONException e1) {
e1.printStackTrace();
}
However, your code is going to continue on if an exception is thrown there, then you'll end up with a NullPointerException, so you should move the for-loop into the try-catch as well.
Realistically, though, you should just use a JSONArrayRequest if you're going to be expecting a JSONArray.
i want to toast"Error" when jsonarray is empty
Simple enough.
arr = new JSONArray(response);
if (arr.length() == 0) {
// TODO: Toast
}

I would simply add two checks to your onResponse method:
...
public void onResponse(String response) {
// Check if the response itself is an empty string or null
if(TextUtils.isEmpty(response)) {
// Show your user feedback
return;
}
Datas.imageIds = new String[response.length()];
JSONArray arr = null;
try {
arr = new JSONArray(response);
// Check if your JSON has no elements in it
if(arr.length == 0) {
// Show your user feedback
return;
}
} catch (JSONException e1) {
e1.printStackTrace();
}
...

You have declared JSONArray arr = null;
After that you assign the server's JSON to that JSONArray.
Add a line after getting that
if(arr==null)
{
//toast
}
else
{
//whatever you want to do with JSON
}

StringRequest stringRequest = new StringRequest(com.android.volley.Request.Method.POST, AppConfig.URL_Gallery4,
new Response.Listener<String>() {
#Override
public void onResponse(String response) {
if(response.length()==0){
Toast.makeText(getActivity(),"no data found",Toast.LENGTH_SHORT).show();
}
else{
Datas.imageIds = new String[response.length()];
JSONArray arr = null;
try {
arr = new JSONArray(response);
} catch (JSONException e1) {
e1.printStackTrace();
}
if(arr.length()>0){
int i=0;
for (i = 0; i < arr.length(); i++) {
try {
JSONObject obj = arr.getJSONObject(i);
category = obj.getString("category_name");
selected = obj.getString("album_id");
imagename = obj.getString("org_image_name");
Datas.imageIds[i] = AppConfig.URL_IMAGE_temp+obj.getString("album_image").substring(3);
gridArray.add(new Item_album(Datas.imageIds[i]));
} catch (JSONException e) {
e.printStackTrace();
}
}
final int xl = i;
adapter = new CustomGrid_Album(kill.this,xl,gridArray);
adapter.notifyDataSetChanged();
grid1.setAdapter(adapter);
}else{
Toast.makeText(getActivity(),"no data found",Toast.LENGTH_SHORT).show();
}
}
pDialog.dismiss();
}
}, new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
Toast.makeText(getApplicationContext(), "No images in this gallery", Toast.LENGTH_SHORT).show();
error.printStackTrace();
}
})
{
#Override
protected Map<String, String> getParams() {
Map<String, String> params = new HashMap<String, String>();
params.put("id", Uid);
return params;
}
};

Use the below code to check whether response is null or not and in object check whether it is having key or data with key is not null
if(response!=null){
try {
Datas.imageIds = new String[response.length()];
JSONArray arr = new JSONArray(response);
for (int i = 0; i < arr.length(); i++) {
try {
JSONObject obj = arr.getJSONObject(i);
if(obj!=null){
if(obj.has("category_name") && !obj.isNull("category_name"){
category = obj.getString("category_name");
}
if(obj.has("album_id") && !obj.isNull("album_id"){
selected = obj.getString("album_id");
}
if(obj.has("org_image_name") && !obj.isNull("org_image_name"){
imagename = obj.getString("org_image_name");
}
if(obj.has("album_image") && !obj.isNull("album_image"){
Datas.imageIds[i] = AppConfig.URL_IMAGE_temp+obj.getString("album_image").substring(3);
gridArray.add(new Item_album(Datas.imageIds[i]));
}
}
} catch (JSONException e) {
e.printStackTrace();
}
}
final int xl = i;
adapter = new CustomGrid_Album(kill.this,xl,gridArray);
adapter.notifyDataSetChanged();
grid1.setAdapter(adapter);
pDialog.dismiss();
} catch (JSONException e1) {
e1.printStackTrace();
}
}

You are using StringRequest, instead of that use JsonArrayRequest to make request as below, so you will get response in onResponse methode when there is a valid JSONArray in response, and if there is no data then you will get response in onError method
JsonArrayRequest rReq = new JsonArrayRequest(Request.Method.GET,"url", new JSONObject(), new Response.Listener() {
#Override
public void onResponse(JSONArray response) {
Log.e(TAG, "onResponse: "+response.toString() );
}
}, new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
Log.e(TAG, "onErrorResponse: "+error.getMessage() );
}
})

Android: Updating List within volley

I want to fill a list of items from the internet. For that I am using volley. If I add values to the list manually, it works:
private ArrayList<ImageItem> getData() {
final ArrayList<ImageItem> imageItems = new ArrayList<>();
for (int i = 0; i < 6; i++) {
Bitmap b = null;
ImageItem imageItem = new ImageItem();
imageItem.setImageFromDB("http://192.168.192.200/images/q112898055d4-eb4d-41ef-9c00-0069789740c1.jpg");
imageItems.add(imageItem);
}
return imageItems;
}
But if I use volley, it doesn't work.. The list is empty. In addition to that I have this list for a gridview-adapter. Here is my code with volley:
private ArrayList<ImageItem> getData() {
final ArrayList<ImageItem> imageItems = new ArrayList<>();
final String url = "http://192.168.192.200/getCustomerQuotes.php?9tEqRp93s2t&EsAzJo1EtNM&VuEtfRAPjNU&NTv5hhlsx5Y&uid=112";
// making fresh volley request and getting json
JsonObjectRequest jsonReq = new JsonObjectRequest(Request.Method.GET,
url, null, new Response.Listener<JSONObject>() {
#Override
public void onResponse(JSONObject response) {
Log.e("TAB1ZZ", "url is " + url);
VolleyLog.d("LIKES", "Response: " + response.toString());
if (response != null) {
try {
JSONArray arr = response.getJSONArray("feed");
for (int i = 0; i < 5; i++) {
JSONObject obj = arr.getJSONObject(i);
String imageForDb = StaticVariables.baseUrlForImage + obj.getString("imageName");
Log.e("IAMGEFODB", "is " + imageForDb);
ImageItem imageItem = new ImageItem();
imageItem.setImageFromDB(imageForDb);
imageItems.add(imageItem);
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}
}, new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
}
});
// Adding request to volley request queue
AppController.getInstance().addToRequestQueue(jsonReq);
return imageItems;
}

Volley Object request Returning 0

I Have a Remote Database that contains 6 rows.
Here's my code, I put it in List so that i can get the size,
But it's always returning 0.
public List<Comments> getComments() {
final List<Comments> commentsData = new ArrayList<>();
JsonObjectRequest jsonObjectRequest = new JsonObjectRequest(Request.Method.POST,
showUrl, new Response.Listener<JSONObject>() {
#Override
public void onResponse(JSONObject response) {
try {
JSONArray jsonArray = response.getJSONArray("poi");
for (int i = 0; i < jsonArray.length(); i++) {
JSONObject jsonObject = jsonArray.getJSONObject(i);
Comments current = new Comments();
current.image = "drawable://" + R.drawable.juandirection_placeholder;
current.title = jsonObject.getString("title");
current.comment = jsonObject.getString("comment");
current.date = jsonObject.getString("date");
current.rating = Integer.parseInt(jsonObject.getString("rating"));
commentsData.add(current);
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}, new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
}
});
VolleyHelper.getInstance(getApplicationContext()).addToRequestQueue(jsonObjectRequest);
return commentsData;
}
I need the size for some use.
Why is it always returning zero?
I even tried adding a counter++ inside for loop.
But when i get the value of the counter its still zero.

JsonObjectRequest run on a background thread. That's why you getting the list size 0. you must work into the public void onResponse(JSONObject response) {} function .
Exmp.
#Override
public void onResponse(JSONObject response) {
try {
JSONArray jsonArray = response.getJSONArray("poi");
for (int i = 0; i < jsonArray.length(); i++) {
JSONObject jsonObject = jsonArray.getJSONObject(i);
Comments current = new Comments();
current.image = "drawable://" + R.drawable.juandirection_placeholder;
current.title = jsonObject.getString("title");
current.comment = jsonObject.getString("comment");
current.date = jsonObject.getString("date");
current.rating = Integer.parseInt(jsonObject.getString("rating"));
commentsData.add(current);
}
// **you may call function and pass the list value to update your ui component. you will get the real size of list here.**
} catch (JSONException e) {
e.printStackTrace();
}
}