Develop Reference

get JSON Array from local server in android 6.0 with HttpURLConnection

I am trying to get a JSON Array from this local server for five days:
localhost/match_picture/service.php?action=read
and i can't do it !!
I search it in google and read too many documentations !
here is my code:
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
public class WebService {
public static String readUrl(String server_url) {
BufferedReader bufferedReader = null;
try {
URL url = new URL(server_url);
HttpURLConnection con = (HttpURLConnection) url.openConnection();
StringBuilder sb = new StringBuilder();
bufferedReader = new BufferedReader(new InputStreamReader(con.getInputStream()));
String json;
while ((json = bufferedReader.readLine()) != null) {
sb.append(json+"\n");
}
return sb.toString();
}catch (Exception e) {
e.printStackTrace();
}
return null;
}
}
and it's Main_Activity:
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.Toast;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.util.ArrayList;
public class Activity_main extends AppCompatActivity {
private ArrayList<StructAcount> netAcount = new ArrayList<StructAcount>();
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
String result= WebService.readUrl("http://localhast/match_picture/service.php?action=read");
if (result != null) {
try {
JSONArray tasks = new JSONArray(result);
for (int i=0; i<tasks.length(); i++) {
StructAcount acount= new StructAcount();
JSONObject object = tasks.getJSONObject(i);
acount.id = object.getLong("user_id");
acount.name = object.getString("user_name");
acount.email = object.getString("user_email");
netAcount.add(acount);
}
} catch (JSONException e) {
e.printStackTrace();
}
}
for (StructAcount acount: netAcount) {
Toast.makeText(Activity_main.this, "username: " + acount.name + "\n" + "useremail: " + acount.email , Toast.LENGTH_SHORT).show();
}
}
}
it is runing on emulator and crashes in this line:
bufferedReader = new BufferedReader(new InputStreamReader(con.getInputStream()));
and i dont know why ...
I am Searching for five days!!!!
I can do it with HttpClient
but i want to be update
I saw a vidoe in youtube that create a class in Main_Activity extends AsyncTask and make connenction in doInBackground(String... params). I try that and that works correcly. but because I want to do it in anoder class (WebService) and I dont know how can i sent result to Main_Activity , I remove that class extended from AsyncTask.
thank's for your help
sorry for my poor english

You have a NetworkOnMainThreadException to begin with.
And your app crashes.
Google how to solve it.

consuming rest web service in android

I'am following this tutorial for calling a web service in android & it works great, http://androidexample.com/Restful_Webservice_Call_And_Get_And_Parse_JSON_Data-_Android_Example/index.php?view=article_discription&aid=101
yet when i try to call another webservice using this code, just replacing the serverURL, the app gets blocked in th pre-execute(), can anyone tell me what else should I change ? I thought there was a common code for all web services ?
mainActivity.java
import android.app.ProgressDialog;
import android.os.AsyncTask;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import org.apache.http.client.HttpClient;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.UnsupportedEncodingException;
import java.net.URL;
import java.net.URLConnection;
import java.net.URLEncoder;
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button GetData = (Button) findViewById(R.id.GetServerData);
GetData.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
// WebServer Request URL
String serverURL = "http://androidexample.com/media/webservice/JsonReturn.php";
// String serverURL = "http://hmkcode.appspot.com/rest/controller/get.json";
// String serverURL="http://gdata.youtube.com/feeds/api/videos?q=Android&v=2&max-results=20&alt=jsonc&hl=en";
// Use AsyncTask execute Method To Prevent ANR Problem
new LongOperation().execute(serverURL);
}
}
);
}
class LongOperation extends AsyncTask<String, Void, Void> {
private final HttpClient Client = new DefaultHttpClient();
private String Content;
private String Error = null;
private ProgressDialog Dialog = new ProgressDialog(MainActivity.this);
String data = "";
TextView uiUpdate = (TextView) findViewById(R.id.output);
TextView jsonParsed = (TextView) findViewById(R.id.jsonParsed);
protected void onPreExecute() {
// NOTE: You can call UI Element here.
//Start Progress Dialog (Message)
Dialog.setMessage("Please wait..");
Dialog.show();
}
// Call after onPreExecute method
protected Void doInBackground(String... urls) {
/************ Make Post Call To Web Server *********/
BufferedReader reader=null;
// Send data
try
{
// Defined URL where to send data
URL url = new URL(urls[0]);
// Send POST data request
URLConnection conn = url.openConnection();
conn.setDoOutput(true);
OutputStreamWriter wr = new OutputStreamWriter(conn.getOutputStream());
wr.write( data );
wr.flush();
// Get the server response
reader = new BufferedReader(new InputStreamReader(conn.getInputStream()));
StringBuilder sb = new StringBuilder();
String line = null;
// Read Server Response
while((line = reader.readLine()) != null)
{
// Append server response in string
sb.append(line + " ");
}
// Append Server Response To Content String
Content = sb.toString();
}
catch(Exception ex)
{
Error = ex.getMessage();
}
finally
{
try
{
reader.close();
}
catch(Exception ex) {}
}
/*****************************************************/
return null;
}
protected void onPostExecute(Void unused) {
// NOTE: You can call UI Element here.
// Close progress dialog
Dialog.dismiss();
if (Error != null) {
uiUpdate.setText("Output : " + Error);
} else {
// Show Response Json On Screen (activity)
uiUpdate.setText(Content);
//String OutputData = MainActivity.parse(Content);
//Show Parsed Output on screen (activity)
//jsonParsed.setText(OutputData);
}
}
}
}

I changed send PostRequest with this code: //SEND Get data reques HttpURLConnection conn = (HttpURLConnection) url.openConnection(); conn.setRequestMethod("GET");& it works

httpclient does not work in asynctask

i am using httpclient in asynctask doInBackground for get my php-session value
this is my Java codes:
package com.example.example;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import org.apache.http.HttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.Activity;
import android.app.ProgressDialog;
import android.os.AsyncTask;
import android.os.Bundle;
public class MainActivity extends Activity {
private String aktuell_date_u,set_check;
public static DefaultHttpClient client = new DefaultHttpClient();
private ProgressDialog pd;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.login_main);
pd = new ProgressDialog(MainActivity.this);
pd.setMessage("bitte warten...");
pd.show();
new get_sessions();
}
private class get_sessions extends AsyncTask<String, Void, JSONObject> {
#Override
protected JSONObject doInBackground(String... arg0) {
HttpGet post = new HttpGet("http://www.example.com/getsessions.php");
try {
HttpResponse response = client.execute(post);
BufferedReader rd = new BufferedReader(new InputStreamReader(response.getEntity().getContent()));
StringBuilder sb = new StringBuilder();
String line = "";
while ((line = rd.readLine()) != null) {
sb.append(line);
break;
}
return new JSONObject(sb.toString());
} catch (JSONException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
protected void onPostExecute(JSONObject result){
aktuell_date_u = result.optString("aktuell_date_u").toString();
set_check = result.optString("set_check").toString();
pd.cancel();
}
}
}
and this is my php codes:
<?php
session_start();
header('content-type: aplication/json; charset=utf-8');
setcookie("cookie_test", date('U'));
$aktuell_date_u=date('U');
$_SESSION['set_check']=md5($aktuell_date_u);
echo '{"aktuell_date_u":"'.$aktuell_date_u.'","set_check":"'.$_SESSION['set_check'].'"}';
?>
the PregressDialog loads and loads ...
what i'm doing wrong, because my httpclient codes work out of doInBackground
Special thanks

You're not calling the AsyncTask's execute() method, so the AsyncTask never runs. Instead of
new get_sessions();
You need to call:
new get_sessions().execute(null);
As you're not using the arguments passed to doInBackground(), I'm not sure why you've defined them as String.
You should probably also look at some basic training on Java coding conventions and follow them - things like making Class names begin with an uppercase letter and camel casing them rather than using underscores. Following conventions makes your code easier for other people to read.

Pass parameter to a URL AsyncTask android

I'm developing an app and now I have to pass a parameter to a RESTful Service's URL. I'm using AsyncTask, and I need to pass a text from a list view as a parameter to the URL, for example: the URL is http://ip:7001/product?product_name=PARAM I need to get the text from the selected item from my list view, and pass as a parameter in PARAM, using AsyncTask. I've already got the text from the item in the listView, now I just need to pass it as a parameter.
This is my AsycTask class:
package com.tumta.henrique.teste;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLEncoder;
import java.util.ArrayList;
import java.util.List;
import com.tumta.henrique.teste.ProdutoFragment;
/**
* Created by Henrique on 18/05/2015.
*/
public class FiltraProduto extends AsyncTask<String, Void, List<String>> {
private ConsultaConcluidaFiltroProdutoListener listener;
public static String URL_STRING = "http://192.168.0.20:7001/com.henrique.rest/api/v1/status/pro_filtro?pro_nome=";
public FiltraProduto(ConsultaConcluidaFiltroProdutoListener listener) {
this.listener = listener;
}
private List<String> InterpretaResultado(String resultado) throws JSONException {
JSONObject object = new JSONObject(resultado);
JSONArray jsonArray = object.getJSONArray("produto");
//JSONObject jsonProduto = jsonArray.getJSONObject(0);
// String id = jsonProduto.getString("pro_id");
//proId = id;
List<Object> listaNomes = new ArrayList<>();
for (int i = 0; i < jsonArray.length(); i++) {
JSONObject jsonProdutoInfo = jsonArray.getJSONObject(i);
String proNome= jsonProdutoInfo.getString("pro_nome");
double proPreco = jsonProdutoInfo.getDouble("pro_preco");
double proSdAtual = jsonProdutoInfo.getDouble("pro_sdAtual");
listaNomes.add(i, proNome);
listaNomes.add(i, proPreco);
listaNomes.add(i, proSdAtual);
}
List<String> strings = new ArrayList<String>();
for (Object o : listaNomes) {
strings.add(o != null ? o.toString() : null);
}
return strings;
}
private String ConsultaServidor() throws IOException {
InputStream is = null;
try {
URL url = new URL(URL_STRING);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setConnectTimeout(10000);
conn.setReadTimeout(15000);
conn.setRequestMethod("GET");
conn.setDoInput(true);
conn.connect();
conn.getResponseCode();
is = conn.getInputStream();
Reader reader = null;
reader = new InputStreamReader(is);
char[] buffer = new char[2048];
reader.read(buffer);
return new String(buffer);
} finally {
if (is != null) {
is.close();
}
}
}
#Override
protected List<String> doInBackground(String... params) {
try {
String resultado = ConsultaServidor();
return InterpretaResultado(resultado);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return null;
}
#Override
protected void onPostExecute(List<String> result) {
listener.onConsultaConcluida(result);
super.onPostExecute(result);
}
public interface ConsultaConcluidaFiltroProdutoListener {
void onConsultaConcluida(List<String> result);
}
}
In the URL_STRING I need to pass the param at pro_nome=?
Here I get the item text. This is in my Fragment that has the List View:
public String retornaParam(String param){
return param;
}
#Override
public void onConsultaConcluida(List<String> result) {
final ListView listaProdutos = (ListView) getView().findViewById(R.id.listaprodutos);
ArrayAdapter arrayAdapter = new ArrayAdapter<>(getView().getContext(),android.R.layout.simple_list_item_1, result);
listaProdutos.setAdapter(arrayAdapter);
listaProdutos.setOnItemClickListener(new AdapterView.OnItemClickListener() {
public void onItemClick(AdapterView<?> parentAdapter, View view, int position,
long id) {
String nomeProduto = listaProdutos.getItemAtPosition(position).toString();
retornaParam(nomeProduto);
Intent intent = new Intent(getActivity(), DetalhesProdutoActivity.class);
//intent.putExtra("pro_nome", listaProdutos.getItemAtPosition(position).toString());
startActivity(intent);
}
});
}
I get the text and store it in param from the retornaParam method.
Does somebody know how to do it?
If you need more information, just let me know.

You pass in params to an AsyncTask using:
YourAsyncTask.execute(yourview.getText(), "and", "more", "params");
You can then access them in
#Override
protected String doInBackground(String... params) {
URL_STRING += params[0];
...

Just add the following code before sending executing your httpClient:
URL_STRING + = textInsideYourTextView;
It should work, just avoid to manipulate your ui elements outside your UI thread.

Android code stop responding when the edit text left empty

hi i am new learner of android and java.below this is my code. I having trouble to know where is the problem.
when i debug few times, it automatically enter debug mode after that. to fix that i have to restart the phone again. I check with other apps, it work just fine. just for the apps that i currently working on.
problem :
1. if i didn't enter data into the "dateTo" the program will stopped.
2. enter debug mode itself.
3. when i get the data from the array atList, then i key in another 'dateTo" to retrieve another data, but it doesn't replace the current data value. tq
package com.example.m2mai;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.sql.Timestamp;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import org.json.JSONArray;
import org.json.JSONObject;
import android.app.Activity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;
public class RetrieveActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_retrieve);
}
public ArrayList<String> atList=new ArrayList<String>();
public ArrayList<String> dataList=new ArrayList<String>();
public void getStream(View v)
{
new MyAsyncTask().execute();
}
private class MyAsyncTask extends AsyncTask<String, Void, String>
{
protected String doInBackground(String... params)
{
return getData();
}
public long getDateTo()
{
EditText toText = (EditText)findViewById(R.id.dateTo);
String To = toText.getText().toString();
DateFormat dateFormatTo = new SimpleDateFormat("dd/MM/yyyy");
Date dateTo = null;
try {
dateTo = dateFormatTo.parse(To);
} catch (java.text.ParseException e) {
e.printStackTrace();
}
long timeTo = dateTo.getTime();
new Timestamp(timeTo);
return timeTo/1000;
}
protected String getData()
{
String toTS = ""+getDateTo();
String decodedString="";
String returnMsg="";
String request = "http://api.carriots.com/devices/{API_KEY}/streams/?order=-1&max=2&at_to="+toTS;
URL url;
HttpURLConnection connection = null;
try {
url = new URL(request);
connection = (HttpURLConnection) url.openConnection();
//establish the parameters for the http post request
connection.addRequestProperty("carriots.apikey", "somekey");
connection.addRequestProperty("Content-Type", "application/json");
connection.setRequestMethod("GET");
//create a buffered reader to interpret the incoming message from the carriots system
BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream()));
while ((decodedString = in.readLine()) != null)
{
returnMsg+=decodedString;
}
in.close();
connection.disconnect();
JSONObject nodeRoot = new JSONObject(returnMsg);
JSONArray res = nodeRoot.getJSONArray("result");
for (int i = 0; i < res.length(); i++)
{
JSONObject childJSON = res.getJSONObject(i);
if (childJSON.get("data")!=null)
{
String value = childJSON.getString("data");
dataList.add(value);
JSONObject node=new JSONObject(value);
atList.add(node.get("temperature").toString());
}
}
}
catch (Exception e)
{
e.printStackTrace();
returnMsg=""+e;
}
//Log.d("returnMsg",returnMsg.toString());
return returnMsg;
}
protected void onPostExecute(String result)
{
//show the message returned from Carriots to the user
Toast.makeText(getApplicationContext(), result, Toast.LENGTH_LONG).show();
EditText myData1=(EditText)findViewById(R.id.editText1);
myData1.setText(atList.get(0));
EditText myData=(EditText)findViewById(R.id.editText2);
myData.setText(atList.get(1));
}
}
}

This line long timeTo = dateTo.getTime(); will throw a NullPointerException when the dateFormatTo.parse method throws a ParseException. This is going to happen when you come into the method with the To string not matching the specified format.
You're not exiting out of the flow so the long...getTime(); line runs, but dateTo is null resulting in a crash.
In the onPostExecute; you aren't verifying that atList has multiple elements. A JSON parse failure will leave atList empty and cause an index bounds exception for those 2 get calls.
These may not be the solutions to what you're seeing; but they will crash the app when these are hit in very likely situations; including the one you describe of an empty string for To.
As the comments mention; the logs will help see what's actually happening; but this is too big for a comment and those points are going to cause problems.