Develop Reference

Fetching array from json not working

Currently I am working with a project where I need to get some data from remote server as JSON then need to extract array. Here I am getting data successfully, But problems are near while loop.
I am getting data from remote server successfully.
For example my remote url giving output as:
{"id": "1","amount": "1000","course_code": "BASIC","course": "Basic Course","content": "Sample","thumb": "sample.png"},
{"id": "2","amount": "2000","course_code": "ADVANCED","course": "Advanced Course","content": "Sample","thumb": "sample.png"}`
Code
try {
ur = "http://localhost/getsample.php";
URL url = new URL(ur);
HttpURLConnection httpURLConnection = (HttpURLConnection)url.openConnection();
InputStream inputStream = httpURLConnection.getInputStream();
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
String line="";
while (line !=null){
line = bufferedReader.readLine();
data = data+line;
}
data = data.replace("null", "");
JSONArray JA = new JSONArray(data);
for (int i=0;i<JA.length();i++){
JSONObject JO = (JSONObject) JA.get(i);
idArray = idArray + JO.get("id") + ",";
amountArray = amountArray + JO.get("amount") + ",";
course_codeArray = course_codeArray + JO.get("course_code") + ",";
courseArray = courseArray + JO.get("course") + ",";
contentArray = contentArray + JO.get("content") + ",";
thumbArray = thumbArray + JO.get("thumb") + ",";
}
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (JSONException e) {
e.printStackTrace();
}

The data you get from the server are at JSON format but they are not Array . this is an object ,
{"id": "1","amount": "1000","course_code": "BASIC","course": "Basic Course","content": "Sample","thumb": "sample.png"},{"id": "2","amount": "2000","course_code": "ADVANCED","course": "Advanced Course","content": "Sample","thumb": "sample.png"}
So you have to loop inside the json object like
for (var key in jsonResponse) {
if (jsonResponse.hasOwnProperty(key)) {
console.log(key + " -> " + jsonResponse[key]);
}
}
EDIT : If you have multiple Objects inside an object you have to loop inside them ( external for) like for(var i in JsonObject)

Your Code is should be like According to your current Response
try{
JSONObject jso = new JSONObject(data);
amountArray =jsonObject.getString("amount");
course_codeArray =jsonObject.getString("yourNextKey");
courseArray = jsonObject.getString("yourNextKey");
contentArray = jsonObject.getString("yourNextKey");
thumbArray = jsonObject.getString("yourNextKey");
}
catch (JSONException e) {
e.printStackTrace();
}

How to split parsed String data without special characters?

I parsed this data from Wikipedia and trying to get only characters from here. But the result comes with \n* in the front of data.
"": "=== 고양이의 종류 ===\n [[시암고양이]]\n* [[페르시안 네브스카야]]\n* [[페르시안]]\n*
[[노르웨이지언 포레스트]]\n* [[터키시 앙고라]]\n* [[아메리칸 숏헤어]]\n* [[브리티시 숏헤어]]\n*
[[러시안블루]]\n* [[뱅갈]]\n* [[메인쿤]]\n* [[랙돌]]\n* [[히말라얀]]\n* [[재패니즈
밥테일]]\n* [[오리엔탈 숏헤어]]\n* [[피터볼드]]\n* [[스코티시 폴드]]\n* 스코티시 스트레이트\n*
[[하일랜드 폴드]]\n* [[시베리안 포레스트]]\n* [[터키시 반]]\n* [[코리안 쇼트헤어]]\n*
[[올블랙]]\n* [[사바나캣]]\n* [[쿠나]]\n* [[아비시니안]]\n* 먼치킨"
This is my code.
try {
URL url = new URL("https://ko.wikipedia.org/w/api.php?action=query&prop=revisions&rvprop=content&rvsection=20&titles=%EA%B3%A0%EC%96%91%EC%9D%B4&format=json");
URLConnection con = url.openConnection();
InputStream is = con.getInputStream();
InputStreamReader isr = new InputStreamReader(is);
BufferedReader reader = new BufferedReader(isr);
while(true){
String data = reader.readLine();
if(data == null) break;
result += data;
}
JSONObject obj = new JSONObject(result);
JSONObject query = (JSONObject) obj.get("query");
JSONObject pages = (JSONObject) query.get("pages");
JSONObject pageid = (JSONObject) pages.get("93349");
JSONArray revisions = (JSONArray) pageid.get("revisions");
String catcat = String.valueOf(revisions);
String star = "\n*";
catcat = catcat.replaceAll("\\[\\[","").replaceAll("\\]\\]",",").replaceAll("\\r|\\n", "").replaceAll(star,"");
String[] catcategory = catcat.split(",");
for (int i = 0; i<catcategory.length;i++){
list.add(catcategory[i]);
}
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (JSONException e) {
e.printStackTrace();
}
Result for this looks like
\n시암고양이
\n페르시안
and I want to remove \n*.

How to split parsed String data without special characters?
Try this piece of code, It's removed \n* , Then you can add _result_word to your list.
for (int i = 0; i < catcategory.length; i++) {
try {
String _result_word = catcategory[i].replaceFirst("\\\\n", "").replace("*", "");
//String _result_word=catcategory[i].replaceFirst("\\\\n", "").replace("*", "").replaceFirst("\\\\n", "").replace("*", "");
System.out.println("" + _result_word);
list.add(_result_word);
} catch (Exception ex) {
System.out.println("Special Exception occurred at index : i = " + i);
ex.printStackTrace();
}
}

Everything correct except one line where you need escape asterisk character and escape slash character
String star = "\\\\n\\*";
str.replaceAll(star, "");

How to read multiple jsonArrays from a file?

I want to read many jsonArrays from a file.
these are the JsonArrays in the file:
[{name:"John",preis:"123",bild:1235},
{name:"Smith",preis:"256",bild:7205},
{name:"Steeven",preis:"632",bild:324035}]
[{name:"Hans",preis:"85",bild:1005},
{name:"Peter",preis:"420",bild:22205},
{name:"Joe",preis:"200",bild:3240}]
[{name:"Jane",preis:"355",bild:10505},
{name:"Calith",preis:"630",bild:96505},
{name:"Eva",preis:"260",bild:32440}]
I can not read the whole file, but i can read only the first jsonArray from the file.
here is my code to read it:
ArrayList<Werkzeug> myWerkzeuge = new ArrayList<Werkzeug>();
String alteBestellung = "";
try {
FileInputStream fileInputStream = openFileInput(fileName);
InputStreamReader inputStreamReader = new InputStreamReader(fileInputStream);
BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
String line;
while ( (line = bufferedReader.readLine()) != null){
alteBestellung = alteBestellung + line;
}
JSONArray jsonArray = new JSONArray(alteBestellung);
for (int i = 0; i<jsonArray.length(); ++i){
JSONObject jsonObject = jsonArray.getJSONObject(i);
String name_werkzeuge = (String) jsonObject.get("name");
String preis_werkzeuge = (String) jsonObject.get("preis");
Integer bild_werkzeuge = Integer.valueOf( (String)jsonObject.get("bild") );
myWerkzeuge.add( new Werkzeug(name_werkzeuge, preis_werkzeuge, bild_werkzeuge));
}
fileInputStream.close();
inputStreamReader.close();
bufferedReader.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (JSONException e) {
e.printStackTrace();
}
String bestellung = " ";
for (int i = 0; i< myWerkzeuge.size(); ++i) {
bestellung = bestellung + "\n" + myWerkzeuge.get(i).getName() + " " + myWerkzeuge.get(i).getPreis() + " €" + myWerkzeuge.get(i).getBild();
}
bestellungsTextView.setText( bestellung );
How to read these three jsonArrays from this file?

What you need is a valid json.
You probably want a JsonArray of JsonArray :
[
[{name:"John",preis:"123",bild:1235},
{name:"Smith",preis:"256",bild:7205},
{name:"Steeven",preis:"632",bild:324035}],
[{name:"Hans",preis:"85",bild:1005},
{name:"Peter",preis:"420",bild:22205},
{name:"Joe",preis:"200",bild:3240}],
[{name:"Jane",preis:"355",bild:10505},
{name:"Calith",preis:"630",bild:96505},
{name:"Eva",preis:"260",bild:32440}]
]

This is not valid json .
First of all make a valid json.

Why isn't my for-loop executing?

In my try block i have a for loop which I'm certain isn't working as when I log in the for loop I get nothing back meaning in my application the loop isn't being accessed.
Here is my try block which includes the for loop:
try
{
HttpURLConnection httpConn = (HttpURLConnection) conn;
httpConn.setAllowUserInteraction(false);
httpConn.setInstanceFollowRedirects(true);
httpConn.setRequestMethod("GET");
httpConn.connect();
response = httpConn.getResponseCode();
if (response == HttpURLConnection.HTTP_OK)
{
anInStream = httpConn.getInputStream();
InputStreamReader in= new InputStreamReader(anInStream);
BufferedReader bin= new BufferedReader(in);
String line = new String();
while (( (line = bin.readLine())) != null)
{
result = result + line;
}
}
menuItems = new ArrayList<HashMap<String, String>>();
Log.v(TAG, "index1=" + menuItems);
Handler parser = new Handler();
String xml = result; // getting XML
Document doc = parser.getDomElement(xml);
NodeList nl = doc.getElementsByTagName(KEY_FUEL);
Log.v(TAG, "index2=" + nl);
for (int i = 0; i < nl.getLength(); i++)
{
Log.v(TAG, "index3=" + nl);
HashMap<String, String> map = new HashMap<String, String>();
Element e = (Element) nl.item(i);
map.put(KEY_HIGHEST, parser.getValue(e, KEY_HIGHEST));
map.put(KEY_AVERAGE, parser.getValue(e, KEY_AVERAGE));
map.put(KEY_LOWEST, parser.getValue(e, KEY_LOWEST));
map.put(KEY_LINK, parser.getValue(e, KEY_LINK));
Log.v(TAG, "index4=" + map);
menuItems.add(map);
Log.v(TAG, "index5=" + menuItems);
}
}
catch (IOException ex)
{
try
{
throw new IOException("Error connecting");
}
catch (IOException e)
{
e.printStackTrace();
}
}
return menuItems;
i added the catch and return for completeness incase perhaps these are the cause. Any help would be appreciated.

Have you checked whether your NodeList is empty? If your getElementsByTagName call returns an empty list, then the length of it will be 0, and your for loop will be skipped because the termination condition will be met before the first iteration. Try logging the length of nl.

Can't POST data to site using HttpURLConnection on Android

I'm essentially trying to mimic what's been done here through the Android app but for some reason data doesn't get returned as soon as it attempts to post data (it returns fine when I delete the writer.write(finalResult) line).
All I want right now is to be able to search for a user's data once I've sent the username.
Here's my code below:
try {
URL u = new URL(url);
HttpURLConnection c = (HttpURLConnection) u.openConnection();
c.setRequestMethod("POST");
c.setRequestProperty("Content-length", "0");
c.setConnectTimeout(timeout);
c.setReadTimeout(timeout);
c.setDoInput(true);
c.setDoOutput(true);
//Attempting to send data!
List<NameValuePair> params = new ArrayList<NameValuePair>();
params.add(new BasicNameValuePair("username", paramValue));
OutputStream os = c.getOutputStream();
BufferedWriter writer = new BufferedWriter(
new OutputStreamWriter(os, "UTF-8"));
String finalResult = getQuery(params);
Log.d("params", finalResult);
writer.write(finalResult);
writer.close();
os.close();
c.connect();
int status = c.getResponseCode();
switch (status) {
case 200:
case 201:
BufferedReader br = new BufferedReader(new InputStreamReader(c.getInputStream()));
StringBuilder sb = new StringBuilder();
String line;
while ((line = br.readLine()) != null) {
sb.append(line+"\n");
}
br.close();
result = sb.toString();
}
} catch (MalformedURLException ex) {
Log.e("log_tag", "Error converting result ");
} catch (IOException ex) {
Log.e("log_tag", "Error in http connection ");
}
//json code!
//parse json data
try{
JSONArray jArray = new JSONArray(result);
//for each object in our json array
for(int i =0; i < jArray.length(); i++){
JSONObject json_data =jArray.getJSONObject(i);
String address = "";
//Checks for missing data in address - Need a class for all fields
if (json_data.isNull("address")){
address = "N/A";
}
else
{
address = json_data.getString("address");;
}
//read one line of the response
myListView.setText("Username: "+json_data.getString("username")
+" / " + "Name: " + json_data.getString("name")
+" / " + "E-mail: " + json_data.getString("email")
+" / " + "Address: " + address);
}
}
catch(JSONException e){
Log.e("log_tag", "Error parsing data"+e.toString());
}
}
private String getQuery(List<NameValuePair> params) throws UnsupportedEncodingException
{
StringBuilder result = new StringBuilder();
boolean first = true;
for (NameValuePair pair : params)
{
if (first)
first = false;
else
result.append("&");
result.append(URLEncoder.encode(pair.getName(), "UTF-8"));
result.append("=");
result.append(URLEncoder.encode(pair.getValue(), "UTF-8"));
}
return result.toString();
}
And here is my php script:
<?php
$searchuser = $_GET["username"];
$databasehost = databasehost;
$databasename = database;
$databaseusername = username;
$databasepassword = password;
$con = mysql_connect($databasehost, $databaseusername, $databasepassword) or die(mysql_error());
mysql_select_db($databasename) or die(mysql_error());
$query = "SELECT * FROM testusers";
$sth = mysql_query($query);
if (mysql_errno()) {
header("HTTP/1.1 500 Internal Server Error");
echo $query."\n";
echo mysql_error();
}
else
{
$rows = array();
while ($r = mysql_fetch_assoc($sth)){
$rows[] = $r;
}
print json_encode($rows);
}
?>

Since you set the header Content-Length to be 0, the server doesn't even read your content... So anything you send isn't received. You should set Content-Length to finalResult.length().

remove this,
c.setRequestProperty("Content-length", "0");