I have a spinner on activity a, the spinner values is taken from a table inside database. When a user select the value from the spinner the value will be saved into same database but different table.
Then there is a button to next activity, on the next activity there is another spinner but I need the spinner selection value to display what I have selected on previous activity.
Android Code:
String text;
String url = "http:///10.92.5.51/test/get.php";
String spinURL = "http://10.92.5.51/test/getSpin.php";
private JSONArray result;
private ArrayList<String> districts;
private ArrayList<Integer> position;
Spinner spinex;
TextView spintext;
Button uploadBtn;
Integer r;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main2);
districts = new ArrayList<String>();
spinex = (Spinner) findViewById(R.id.spiner);
spintext = findViewById(R.id.spinText);
uploadBtn = findViewById(R.id.btnUpload);
getData();
spinex.post(new Runnable() {
#Override
public void run() {
spinex.setSelection(4);
}
});
getPosition();
}
private void getData() {
StringRequest stringRequest = new StringRequest(url,
new Response.Listener<String>() {
#Override
public void onResponse(String response) {
JSONObject j = null;
try {
//Parsing the fetched Json String to JSON Object
j = new JSONObject(response);
//Storing the Array of JSON String to our JSON Array
result = j.getJSONArray("result");
getDistrict(result);
} catch (JSONException e) {
e.printStackTrace();
}
}
},
new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
}
});
//Creating a request queue
MySingleton.getInstance(this).addToRequestQueue(stringRequest);
}
private void getPosition() {
StringRequest stringRequest = new StringRequest(spinURL,
new Response.Listener<String>() {
#Override
public void onResponse(String response) {
JSONObject j = null;
try {
//Parsing the fetched Json String to JSON Object
j = new JSONObject(response);
//Storing the Array of JSON String to our JSON Array
result = j.getJSONArray("result");
getSpinPosition(result);
} catch (JSONException e) {
e.printStackTrace();
}
}
},
new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
}
});
//Creating a request queue
MySingleton.getInstance(this).addToRequestQueue(stringRequest);
}
private void getDistrict(JSONArray j) {
//Traversing through all the items in the json array
for (int i = 0; i < j.length(); i++) {
try {
//Getting json object
JSONObject json = j.getJSONObject(i);
//Adding the name of the student to array list
districts.add(json.getString("city_name"));
} catch (JSONException e) {
e.printStackTrace();
}
}
spinex.setAdapter(new ArrayAdapter<String>(Main2Activity.this, android.R.layout.simple_spinner_dropdown_item, districts));
}
private void getSpinPosition(JSONArray j) {
//Traversing through all the items in the json array
try {
//Getting json object
JSONObject json = j.getJSONObject(1);
//Adding the name of the student to array list
r = Integer.valueOf(json.getString("city_id"));
} catch (JSONException e) {
e.printStackTrace();
}
}
Here is the php code:
<?php
require_once('DBConnect.php');
$sql = "select * from city ORDER BY city_id ASC";
$res = mysqli_query($con,$sql);
$result = array();
while($row = mysqli_fetch_array($res)){
array_push($result,
array(
'city_id'=>$row['city_id'],
'city_name'=>$row['city_name'],
)
);
}
echo json_encode(array("result"=>$result));
mysqli_close($con);
I have 2 problem.
Once :
I cant initialize a non-final variable inner method.I want to initialize a variable in JsonRequestbut when I use in it shows me a error -create variable final.
public DataModel[] getContentsUsername(final int count) {
DataModel[] dataModels = new DataModel[count];
for (int i = 0; i < count; i++) {
dataModels[i] = new DataModel();
}
JsonArrayRequest jsonArrayRequest = new JsonArrayRequest("http://www.lmslfm.isteb.ir/message/json.php", new Response.Listener<JSONArray>() {
#Override
public void onResponse(JSONArray response) {
try {
JSONObject jsonObject ;
for (int i = 0; i < count; i++) {
jsonObject = (JSONObject) response.get(i);
dataModels[i].setMessageContent(jsonObject.getString("message_content"));
dataModels[i].setMessageUserName(jsonObject.getString("user_name"));
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}, new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
}
});
jsonArrayRequest.setRetryPolicy(new DefaultRetryPolicy(4000, 0, 0));
RequestQueue requestQueue = Volley.newRequestQueue(context);
requestQueue.add(jsonArrayRequest);
return dataModels;
}
and 2 :
When a app goes to give data from server it takes time and when i want to recieve data from this method i give a empty variable .
how can i use codes to recive from method when data recieved from server or after many seconds .
thanks
This question already has answers here:
How do I parse JSON in Android? [duplicate]
(3 answers)
Closed 5 years ago.
I can parse json from a url in this way and my json looks like this;
[
{"rank":1,"title":"The Shawshank Redemption"},
{"rank":2,"title":"The Godfather"},
{"rank":3,"title":"The Godfather: Part II"},
{"rank":4,"title":"The Dark Knight"}
]
This is my android code and it works perfect;
public class MainActivity extends AppCompatActivity {
private ListView listView;
private SwipeListAdapter adapter;
private List<Movie> movieList;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
listView = (ListView) findViewById(R.id.listView);
movieList = new ArrayList<>();
adapter = new SwipeListAdapter(this, movieList);
listView.setAdapter(adapter);
runOnUiThread(new Runnable() {
#Override
public void run() {
fetchMovies();
};
});
}
private void fetchMovies() {
String url = "http://www.url.com/test.json";
JsonArrayRequest req = new JsonArrayRequest(url,
new Response.Listener<JSONArray>() {
#Override
public void onResponse(JSONArray response) {
if (response.length() > 0) {
for (int i = 0; i < response.length(); i++) {
try {
JSONObject movieObj = response.getJSONObject(i);
int rank = movieObj.getInt("rank");
String title = movieObj.getString("title");
Movie m = new Movie(rank, title);
movieList.add(0, m);
} catch (JSONException e) {
}
}
adapter.notifyDataSetChanged();
}
}
}, new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
Toast.makeText(getApplicationContext(), error.getMessage(), Toast.LENGTH_LONG).show();
}
});
MyApplication.getInstance().addToRequestQueue(req);
}
}
I want to parse this json but I couldn't parse this json and I have no idea.
{
"level":[
{
"server":[
{"rank":1,"title":"The Shawshank Redemption"},
{"rank":2,"title":"The Godfather"},
{"rank":3,"title":"The Godfather: Part II"},
{"rank":4,"title":"The Dark Knight"}
]
}
]
}
How Can I do that?
Thank you.
I would strongly suggest to move towards Gson.
Here is the code for fetchMovies if you don't want to make the change:
private void fetchMovies() {
String url = "http://www.url.com/test.json";
JsonObjectRequest req = new JsonObjectRequest(url, null,
new Response.Listener<JSONObject>() {
#Override
public void onResponse(JSONObject response) {
try {
JSONArray level = response.getJSONArray("level");
JSONObject item = level.getJSONObject(0);
JSONArray server = item.getJSONArray("server");
for (int i = 0; i < server.length(); i++) {
try {
JSONObject movieObj = server.getJSONObject(i);
int rank = movieObj.getInt("rank");
String title = movieObj.getString("title");
Movie m = new Movie(rank, title);
movieList.add(0, m);
} catch (JSONException e) {
}
}
adapter.notifyDataSetChanged();
} catch (JSONException e) {
}
}
}, new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
Toast.makeText(getApplicationContext(), error.getMessage(), Toast.LENGTH_LONG).show();
}
});
MyApplication.getInstance().addToRequestQueue(req);
}
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() );
}
})
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();
}
}