Develop Reference

Android Studio: setOnItemClickListener

I have two AppCompatActivitys, both should have an onItemClickListener, but one of them doesn't do anything on click. I've just added a Toast for test reason, later on it should call a function to delete an item from list (with an ajax request)
What am I doing wrong?
I have made custom list and custom adapter for this - I know, I am new to Android Studio, but the other Activity works fine, and I cant find any differences.
public class ActivityListofProducts extends AppCompatActivity {
ProgressDialog pd;
SharedPreferences preferences;
String userid;
String session;
String list_id = "-1"; // or other values
String appVersion = "";
private ArrayList<listProductItem> myProducts = new ArrayList<listProductItem>();
private ArrayList<listProductItem> groceryFilterProducts = new ArrayList<listProductItem>();
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
handleIntent(getIntent());
setContentView(R.layout.activity_list_of_products);
this.setTitle(getString(R.string.grocery_list));
Bundle b = getIntent().getExtras();
SwipeRefreshLayout swipeRefreshLayout = (SwipeRefreshLayout) findViewById(R.id.refreshLayout);
if (b != null)
list_id = b.getString("list_id");
Toast.makeText(this, "List to open " + " " + list_id, Toast.LENGTH_SHORT).show();
preferences =
getSharedPreferences(this.getPackageName(), this.MODE_PRIVATE);
userid = preferences.getString("userid", "");
session = preferences.getString("session", "");
appVersion = preferences.getString("appVersion", "");
getData();
swipeRefreshLayout.setOnRefreshListener(
new SwipeRefreshLayout.OnRefreshListener() {
#Override
public void onRefresh() {
getData();
swipeRefreshLayout.setRefreshing(false);
}
}
);
}
public void getData() {
AsyncTask<String, String, String> Task_GetListofProducts = new Task_GetListofProducts();
Task_GetListofProducts.execute("https://get-some-json.com");
}
public void initListofProducts(String jsonString) {
Log.i("jsonString",jsonString);
try {
JSONObject jsonResponse = new JSONObject(jsonString);
JSONObject jsonListMode = jsonResponse.getJSONObject("list");
String ListName = jsonListMode.optString("name");
this.setTitle(ListName);
JSONArray jsonMainNode = jsonResponse.optJSONArray("data");
for (int i = 0; i < jsonMainNode.length(); i++) {
JSONObject jsonChildNode = jsonMainNode.getJSONObject(i);
int item_amount = jsonChildNode.optInt("item_amount");
int id = jsonChildNode.optInt("id");
String item_name = jsonChildNode.optString("item_name",">Name<");
int done = jsonChildNode.optInt("done", 0);
String timestamp = jsonChildNode.optString("timestamp", "");
String item_scale = jsonChildNode.optString("item_scale", "x");
String img = jsonChildNode.optString("img", "x");
double bestprice = jsonChildNode.optDouble("bestprice");
//int oitems = jsonChildNode.optInt("oitems", 0);
//int shared = jsonChildNode.optInt("shared", 0);
String outPut = "item_amount:"+ item_amount +" id:"+ id +" item_name:"+ item_name +" done:"+ done +" timestamp:"+ timestamp +" item_scale:"+ item_scale +" img:"+ img;
Log.i("outPut",outPut);
myProducts.add(new listProductItem(id, item_name, item_amount, item_scale, img, done, timestamp, bestprice));
}
final ListView lv = findViewById(R.id.grocery_list_of_products);
lv.setAdapter(new listofProductsAdapter(this, myProducts));
lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> a, View v, int position, long id) {
/*
!! HERE is my problem. This Code seems not to be executed !!
*/
Toast.makeText(ActivityListofProducts.this, "Should handle click now.", Toast.LENGTH_SHORT).show();
}
});
} catch (JSONException e) {
Toast.makeText(getApplicationContext(), "Error" + e.toString(), Toast.LENGTH_SHORT).show();
}
}
public void setProductDone(int pid, int done) {
String url = "put-some-json.com";
new ActivityListofProducts.Task_SetProductDone().execute(url);
}
private class Task_SetProductDone extends AsyncTask<String, String, String> {
protected void onPreExecute() {
super.onPreExecute();
pd = new ProgressDialog(ActivityListofProducts.this);
pd.setMessage("Please wait");
pd.setCancelable(false);
pd.show();
}
protected String doInBackground(String... params) {
HttpURLConnection connection = null;
BufferedReader reader = null;
Log.i("doInBackground",params.toString());
try {
URL url = new URL(params[0]);
connection = (HttpURLConnection) url.openConnection();
connection.connect();
InputStream stream = connection.getInputStream();
reader = new BufferedReader(new InputStreamReader(stream));
StringBuffer buffer = new StringBuffer();
String line = "";
while ((line = reader.readLine()) != null) {
buffer.append(line + "\n");
Log.d("Response: ", "> " + line); //here you will get whole response...... :-)
}
return buffer.toString();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (UnknownHostException e) {
Toast.makeText(ActivityListofProducts.this, "No Internet?", Toast.LENGTH_SHORT).show();
} catch (IOException e) {
e.printStackTrace();
} finally {
if (connection != null) {
connection.disconnect();
}
try {
if (reader != null) {
reader.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}
return null;
}
#Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
if (pd.isShowing()) {
pd.dismiss();
}
Log.i("onPostExecute", result);
}
}
private class Task_GetListofProducts extends AsyncTask<String, String, String> {
protected void onPreExecute() {
super.onPreExecute();
pd = new ProgressDialog(ActivityListofProducts.this);
pd.setMessage("Please wait");
pd.setCancelable(false);
pd.show();
myProducts = new ArrayList<listProductItem>(); //empty list
}
protected String doInBackground(String... params) {
HttpURLConnection connection = null;
BufferedReader reader = null;
Log.i("doInBackground",params.toString());
try {
URL url = new URL(params[0]);
connection = (HttpURLConnection) url.openConnection();
connection.connect();
InputStream stream = connection.getInputStream();
reader = new BufferedReader(new InputStreamReader(stream));
StringBuffer buffer = new StringBuffer();
String line = "";
while ((line = reader.readLine()) != null) {
buffer.append(line + "\n");
Log.d("Response: ", "> " + line); //here you will get whole response...... :-)
}
return buffer.toString();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
if (connection != null) {
connection.disconnect();
}
try {
if (reader != null) {
reader.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}
return null;
}
#Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
if (pd.isShowing()) {
pd.dismiss();
}
initListofProducts(result);
}
}
private class Task_FindProducts extends AsyncTask<String, String, String> {
protected void onPreExecute() {
super.onPreExecute();
pd = new ProgressDialog(ActivityListofProducts.this);
pd.setMessage("Please wait");
pd.setCancelable(false);
pd.show();
myProducts = new ArrayList<listProductItem>(); //empty list
}
protected String doInBackground(String... params) {
HttpURLConnection connection = null;
BufferedReader reader = null;
Log.i("doInBackground",params.toString());
try {
URL url = new URL(params[0]);
connection = (HttpURLConnection) url.openConnection();
connection.connect();
InputStream stream = connection.getInputStream();
reader = new BufferedReader(new InputStreamReader(stream));
StringBuffer buffer = new StringBuffer();
String line = "";
while ((line = reader.readLine()) != null) {
buffer.append(line + "\n");
Log.d("Response: ", "> " + line); //here you will get whole response...... :-)
}
return buffer.toString();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
if (connection != null) {
connection.disconnect();
}
try {
if (reader != null) {
reader.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}
return null;
}
#Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
if (pd.isShowing()) {
pd.dismiss();
}
setFilterProducts(result);
}
}
}

Parse Json data into a Json object

I have a problem with parsing a tag inside a Json object.
My json code is structured like that:
{"giocatori":[{"nome":"Giovanni","cognome":"Muchacha","numero":"1","ruolo":"F-G"},
{"nome":"Giorgio","cognome":"Rossi","numero":"2","ruolo":"AG"},
{"nome":"Andrea","cognome":"Suagoloso","numero":"3","ruolo":"P"},
{"nome":"Salvatore","cognome":"Aranzulla","numero":"4","ruolo":"G"},
{"nome":"Giulio","cognome":"Muchacha","numero":"5","ruolo":"F"}]}
I got the code that let me get the Json file from here: Get JSON Data from URL Using Android? and I'm trying to parse a tag (for example the "nome" tag) into a Json object.
This is the code I got:
public class MainActivity extends AppCompatActivity {
Button btnHit;
TextView txtJson;
ProgressDialog pd;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
btnHit = (Button) findViewById(R.id.btnHit);
txtJson = (TextView) findViewById(R.id.tvJsonItem);
btnHit.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
new JsonTask().execute("https://api.myjson.com/bins/177dpo");
}
});
}
private class JsonTask extends AsyncTask<String, String, String> {
protected void onPreExecute() {
super.onPreExecute();
pd = new ProgressDialog(MainActivity.this);
pd.setMessage("Please wait");
pd.setCancelable(false);
pd.show();
}
protected String doInBackground(String... params) {
HttpURLConnection connection = null;
BufferedReader reader = null;
try {
URL url = new URL(params[0]);
connection = (HttpURLConnection) url.openConnection();
connection.connect();
InputStream stream = connection.getInputStream();
reader = new BufferedReader(new InputStreamReader(stream));
StringBuffer buffer = new StringBuffer();
String line = "";
while ((line = reader.readLine()) != null) {
buffer.append(line+"\n");
Log.d("Response: ", "> " + line);
}
return buffer.toString();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
if (connection != null) {
connection.disconnect();
}
try {
if (reader != null) {
reader.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}
return null;
}
#Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
if (pd.isShowing()){
pd.dismiss();
}
txtJson.setText(result);
}
}
}
I've never worked with this type of file so I'll really appreciate your help!

You can use something like this:
try {
String servResponse = response.toString();
JSONObject parentObj = new JSONObject(servResponse);
JSONArray parentArray = parentObj.getJSONArray("giocatori");
if (parentArray.length() == 0) {
//if it's empty, do something (or not)
} else {
//Here, finalObj will have your jsonObject
JSONObject finalObj = parentArray.getJSONObject(0);
//if you decide to store some value of the object, you can do like this (i've created a nomeGiocatori for example)
nomeGiocatori = finalObj.getString("nome");
}
} catch (Exception e) {
Log.d("Exception: ", "UnknownException");
}
I use this kind of code all the time, works like a charm.

Asynctask android return contents "doinBackground

I would like to retrieve the contents of my variable "$content" in my activity.
But I don't know how to use the return value of my doinbackground.
Can you help me ?
thank you in advance
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
String restURL = "https://proxyepn-test.epnbn.net/wsapi/epn";
RestOperation test = new RestOperation();
test.execute(restURL);
}
private class RestOperation extends AsyncTask<String, Void, String> {
//final HttpClient httpClient = new DefaultHttpClient();
String content;
String error;
ProgressDialog progressDialog = new ProgressDialog(MainActivity.this);
String data = "";
TextView serverDataReceived = (TextView)findViewById(R.id.serverDataReceived);
TextView showParsedJSON = (TextView) findViewById(R.id.showParsedJSON);
// EditText userinput = (EditText) findViewById(R.id.userinput);
#Override
protected void onPreExecute() {
super.onPreExecute();
progressDialog.setTitle("Please wait ...");
progressDialog.show();
}
#Override
protected String doInBackground(String... params) {
BufferedReader br = null;
URL url;
try {
url = new URL(params[0]);
URLConnection connection = url.openConnection();
connection.setDoOutput(true);
OutputStreamWriter outputStreamWr = new OutputStreamWriter(connection.getOutputStream());
outputStreamWr.write(data);
outputStreamWr.flush();
br = new BufferedReader(new InputStreamReader(connection.getInputStream()));
StringBuilder sb = new StringBuilder();
String line = null;
while((line = br.readLine())!=null) {
sb.append(line);
sb.append(System.getProperty("line.separator"));
}
content = sb.toString();
} catch (MalformedURLException e) {
error = e.getMessage();
e.printStackTrace();
} catch (IOException e) {
error = e.getMessage();
e.printStackTrace();
} finally {
try {
br.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
return content;
}
#Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
progressDialog.dismiss();
if(error!=null) {
serverDataReceived.setText("Error " + error);
} else {
serverDataReceived.setText(content);
String output = "";
JSONObject jsonResponse;
try {
jsonResponse = new JSONObject(content);
JSONArray jsonArray = jsonResponse.names();
for (int i = 0; i < jsonArray.length(); i++) {
JSONObject child = jsonArray.getJSONObject(i);
String name = child.getString("name");
String number = child.getString("number");
String time = child.getString("date_added");
output = "Name = " + name + System.getProperty("line.separator") + number + System.getProperty("line.separator") + time;
output += System.getProperty("line.separator");
Log.i("content",content);
}
showParsedJSON.setVisibility(View.INVISIBLE);
showParsedJSON.setText(output);
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
}

You can directly call to the method which exist in activity, from onPostExecute method of asynctask by passing "content" value.
#Override
protected void onPostExecute(String content) {
Activity.yourMethod(content);
}
If you want to return the value from asynctask you can use
content = test.execute(url).get();
but it is not a good practice of asynctask, because it is working as serial execution. So it is not fulfill the use of asynctask for palatalization.Because get() will block the UI thread.

android get url from edit text and use it in rest api to upload data

Here is my android rest request code but the where i get the url from edit text using its id but "getString" gets flagged(can't be resolved). Please help
class RESTRequest
{
//final String ADD_STROKE_URL = "";
final String ADD_STROKE_URL = new String[]{ getString(R.id.buttonUploadURL)};
public Boolean success = null;
private JSONObject params;
private String strokeId;
private HashSet<Point> localPoints;
private StrokeManagerCallback callback;
public static String encode(Object x) {
try {
return URLEncoder.encode(String.valueOf(x),"UTF-8");
} catch (UnsupportedEncodingException e) {
return(String.valueOf(x));
}
}
public RESTRequest(JSONObject params,String strokeId,Set<Point> points,StrokeManagerCallback callback)
{
this.params = params;
this.strokeId = strokeId;
this.localPoints = new HashSet<Point>();
this.localPoints.addAll(points);
this.callback = callback;
new ExecuteREST().execute();
}
private class ExecuteREST extends AsyncTask<Void, Void, String>
{
protected String doInBackground(Void ...arg0)
{
/* Build URL query */
StringBuffer local = new StringBuffer(ADD_STROKE_URL);
if(params != null)
{
local.append("?");
Iterator<?> k = params.keys();
while(k.hasNext()){
try {
String key = (String) k.next();
Object value = params.get(key);
local.append(encode(key));
local.append("=");
local.append(encode(value));
if(k.hasNext()){
local.append("&");
}
}
catch (JSONException e) {e.printStackTrace();}
}
}
HttpURLConnection urlConn = null;
StringBuffer response = new StringBuffer("error");
try
{
URL url = new URL(local.toString());
urlConn = (HttpURLConnection) url.openConnection();
urlConn.setRequestMethod("GET");
urlConn.setDoInput(true);
urlConn.setUseCaches(false);
urlConn.setRequestProperty("Content-Type", "application/json");
urlConn.connect();
//Get Response
InputStream is = urlConn.getInputStream();
BufferedReader rd = new BufferedReader(newInputStreamReader(is));
String line;
response = new StringBuffer();
try{
while((line = rd.readLine()) != null) {
response.append(line);
}
}
finally{
if(urlConn != null){
urlConn.disconnect();
urlConn = null;
}
if(rd != null){
rd.close();
rd = null;
}
}
if(callback != null){
callback.onSuccess(strokeId, localPoints);
}
} catch (ConnectException e) {
callback.onFailure(strokeId, localPoints);
} catch (UnknownHostException e) {
callback.onFailure(strokeId, localPoints);
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (EOFException e) {
response = new StringBuffer("No response from server");
} catch (IOException e) {
e.printStackTrace();
} catch (RuntimeException e) {
e.printStackTrace();
}
finally{
if(urlConn != null){
urlConn.disconnect();
}
}
return response.toString();
}
}

you can get String Resources like this
Resources res = context.getResources();
final String ADD_STROKE_URL = new String[]{ res.getString(R.id.buttonUploadURL)};
and now you can pass that url in AcycncTask class like this
public RESTRequest(JSONObject params,String
strokeId,Set<Point>points,StrokeManagerCallback callback){
this.params = params;
this.strokeId = strokeId;
this.localPoints = new HashSet<Point>();
this.localPoints.addAll(points);
this.callback = callback;
new ExecuteREST(/*Pass url here that you will get in doInBackground method */)
.execute();
}
private class ExecuteREST extends AsyncTask<String, Void, String>{
protected String doInBackground(String ...arg0){
//get your url in arg0 variable
StringBuffer local = new StringBuffer(arg0[0]);
.
.
.
//Rest of yours ...

Android Null pointer exception while using Async Task method [duplicate]

This question already has answers here:
What is a NullPointerException, and how do I fix it?
(12 answers)
Closed 7 years ago.
While executing Async Task in android and getting Json response and while converting response into JSONArray,i am getting NUll pointer Exception.
I am trying fron two days Please help me.
Here is the code to get the Json String.
error is at task.get().
DownloadTask task=new DownloadTask();
task.execute(new String[]{"URL"});
try {
jsonArr=new JSONArray(task.get());
Toast.makeText(getApplicationContext(), jsonArr.toString(), Toast.LENGTH_LONG).show();
for (int i = 0; i < jsonArr.length(); i++) {
obj = jsonArr.getJSONObject(i);
name = obj.getString("name");
phno = obj.getString("phone");
dcount = obj.getString("count");
}
} catch (JSONException e) {
e.printStackTrace();
} catch (InterruptedException e) {
e.printStackTrace();
} catch (ExecutionException e) {
e.printStackTrace();
}
Here Is the Async task code.
class DownloadTask extends AsyncTask<String,Void,String>{
private ProgressDialog mProgressDialog=new ProgressDialog(MainActivity.this);
#Override
protected void onPreExecute(){
mProgressDialog.setMessage("Processing");
mProgressDialog.show();
}
#Override
protected String doInBackground(String... targetURL) {
URL url;
HttpURLConnection connection = null;
try {
url = new URL(targetURL[0]);
connection = (HttpURLConnection)url.openConnection();
connection.setRequestMethod("GET");
connection.setRequestProperty("Content-Type",
"application/json");
connection.setUseCaches (false);
connection.setDoInput(true);
connection.setDoOutput(true);
/* //Send request
DataOutputStream wr = new DataOutputStream (
connection.getOutputStream ());
wr.writeBytes("BID1");
wr.flush();
wr.close();*/
//Get Response
InputStream is = connection.getInputStream();
BufferedReader rd = new BufferedReader(new InputStreamReader(is));
String line;
StringBuffer response = new StringBuffer();
while((line = rd.readLine()) != null) {
response.append(line);
response.append('\r');
}
rd.close();
return response.toString();
} catch (Exception e) {
e.printStackTrace();
return null;
} finally {
if(connection != null) {
connection.disconnect();
}
}
}
#Override
protected void onPostExecute(String result) {
Toast.makeText(getApplicationContext(),result, Toast.LENGTH_SHORT);
mProgressDialog.dismiss();
}
}

You are forgot to call the super method of the onPostExecute
It should be like this
#Override
protected void onPostExecute(String result) {
Toast.makeText(getApplicationContext(),result, Toast.LENGTH_SHORT);
mProgressDialog.dismiss();
super.onPostExecute(result);
}
Other Solution
You can use an interface for your callback
ICallback.java
public interface ICallback {
void onResult(String result);
}
DownloadTask
class DownloadTask extends AsyncTask<String, Void, String> {
private ProgressDialog mProgressDialog = new ProgressDialog(MainActivity.this);
private ICallback callback;
public DownloadTask(ICallback callback) {
this.callback = callback;
}
#Override
protected void onPreExecute() {
//Your Codes Here
}
#Override
protected String doInBackground(String... targetURL) {
//Your Codes Here
}
#Override
protected void onPostExecute(String result) {
//Your Codes Here
callback.onResult(result)
}
}
How to use it
DownloadTask task = new DownloadTask(new ICallback() {
#Override
public void onResult(String result) {
try {
jsonArr=new JSONArray(result);
Toast.makeText(getApplicationContext(), jsonArr.toString(), Toast.LENGTH_LONG).show();
for (int i = 0; i < jsonArr.length(); i++) {
obj = jsonArr.getJSONObject(i);
name = obj.getString("name");
phno = obj.getString("phone");
dcount = obj.getString("count");
}
} catch (JSONException e) {
e.printStackTrace();
} catch (InterruptedException e) {
e.printStackTrace();
} catch (ExecutionException e) {
e.printStackTrace();
}
}
});
task.execute(new String[]{"URL"});