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JSONException on trying to get a value from Json to String

I'm trying to get 2 values from Wikipedia with the next API link:
https://en.wikipedia.org/w/api.php?action=query&generator=random&grnnamespace=0&prop=pageimages&format=json&pithumbsize=500&utf8
because its generated by random, sometimes it doesn't return one of the values I need, but I will solve this later, currently I'm having a problem with accessing the two values I need in the Json, "title" and "source"
The returned Json is like this:
{"batchcomplete":"","continue":{"grncontinue":"0.360395277951|0.360395626487|10429617|0","continue":"grncontinue||"},"query":{"pages":{"38690716":{"pageid":38690716,"ns":0,"title":"Alaine Chartrand","thumbnail":{"source":"https://upload.wikimedia.org/wikipedia/commons/d/d4/Alaine_Chartrand.jpg","width":267,"height":400},"pageimage":"Alaine_Chartrand.jpg"}}}}
this is the code, can anybody figure out why does it go to JSONException?
String API = "https://en.wikipedia.org/w/api.php?action=query&generator=random&grnnamespace=0&prop=pageimages&format=json&pithumbsize=500&utf8";
//open connection with wikipedia.
HttpURLConnection httpcon = (HttpURLConnection) new URL(API).openConnection();
//read all the input from wikipedia.
BufferedReader in = new BufferedReader(new InputStreamReader(httpcon.getInputStream()));
String responseSB = in.lines().collect(Collectors.joining());
in.close();
JSONObject incomingJSON = new JSONObject(responseSB);
//crashes here
String mTitle = incomingJSON.getString("title");
String mUrl = incomingJSON.getString("source");

If you notice the JSON it is randomly generated but with specific format
Case 1
{
"batchcomplete": "",
"continue": {
"grncontinue": "0.720220803439|0.720221273467|12887566|0",
"continue": "grncontinue||"
},
"query": {
"pages": {
"4897672": {
"pageid": 4897672,
"ns": 0,
"title": "New Hope, Sunnyvale, Texas"
}
}
}
}
query and pages were always existed, and in pages the key is always randomly generate, so it is Map<String, JSONObject> map of String key and JSONObject as value, Then you need to get the title value from map values
String API = "https://en.wikipedia.org/w/api.php?action=query&generator=random&grnnamespace=0&prop=pageimages&format=json&pithumbsize=500&utf8";
//open connection with wikipedia.
HttpURLConnection httpcon = (HttpURLConnection) new URL(API).openConnection();
//read all the input from wikipedia.
BufferedReader in = new BufferedReader(new InputStreamReader(httpcon.getInputStream()));
String responseSB = in.lines().collect(Collectors.joining());
in.close();
JSONObject incomingJSON = new JSONObject(responseSB);
Map<String,JSONObject> map = (Map<String, JSONObject>) incomingJSON.getJSONObject("query").getJSONObject("pages");
map.forEach((k,v)->System.out.println(" The key is : "+k+" the title is : "+v.getString("title")));
Case 2 With source
{
"batchcomplete": "",
"continue": {
"grncontinue": "0.165621850014|0.165622038679|37982311|0",
"continue": "grncontinue||"
},
"query": {
"pages": {
"57529788": {
"pageid": 57529788,
"ns": 0,
"title": "Model Store",
"thumbnail": {
"source": "https://upload.wikimedia.org/wikipedia/commons/thumb/2/23/Australia_New_South_Wales_relief_location_map.png/500px-Australia_New_South_Wales_relief_location_map.png",
"width": 500,
"height": 443
},
"pageimage": "Australia_New_South_Wales_relief_location_map.png"
}
}
}
}
So source may not present in every response, handle with try catch
String API = "https://en.wikipedia.org/w/api.php?action=query&generator=random&grnnamespace=0&prop=pageimages&format=json&pithumbsize=500&utf8";
//open connection with wikipedia.
HttpURLConnection httpcon = (HttpURLConnection) new URL(API).openConnection();
//read all the input from wikipedia.
BufferedReader in = new BufferedReader(new InputStreamReader(httpcon.getInputStream()));
String responseSB = in.lines().collect(Collectors.joining());
in.close();
JSONObject incomingJSON = new JSONObject(responseSB);
Map<String,JSONObject> map = (Map<String, JSONObject>) incomingJSON.getJSONObject("query").getJSONObject("pages");
map.forEach((k,v)->{
System.out.println(" The key is : "+k+" the title is : "+v.getString("title"));
//use try catch to get source because you will not get the same response every time
String source = v.getJSONObject("thumbnail").getString("source");
});
}

You can't get title and source directly from JSON response because it has to contain multiple inner objects. Below is the code snap for reading title and source.
// new code
JSONObject incomingJSON = new JSONObject(responseSB);
JSONObject innerObject = incomingJSON.getJsonObject("query").getJsonObject("pages").getJsonObject("38690716");
String mTitle= innerObject.getString("title");
String mUrl= innerObject.getJsonObject("thumbnail").getString("source");
//crashes here
String mTitle = incomingJSON.getString("title");
String mUrl = incomingJSON.getString("source");

try this...
JSONObject incomingJSON = new JSONObject(responseSB);
JSONObject TitleObjects = incomingJSON.getJSONObject("query");
JSONObject j_Objects_01 = TitleObjects.getJSONObject("pages");
JSONObject j_Objects_02 = j_Objects_01.getJSONObject("38690716");
String mTitle = j_Objects_02.getString("title");
JSONObject j_Objects_03 = j_Objects_02.getJSONObject("thumbnail");
String mUrl = j_Objects_03.getString("source");

You should be aware that the page id will change and the thumbnail is optional.
// new code
JSONObject incomingJSON = new JSONObject(responseSB);
JSONObject pages = incomingJSON.getJSONObject("query").getJSONObject("pages");
Iterator<String> it = pages.keys();
while(it.hasNext()) {
JSONObject page = pages.getJSONObject(it.next());
String mTitle= page.getString("title");
if(page.keySet().contains("thumbnail")) {
String mUrl= page.getJSONObject("thumbnail").getString("source");
}
}

So because the ID kept changing, I've decided to go from another approach.
I've used the following code:
Pattern p = Pattern.compile("\"source\":\"(.*?)\",\"width");
Matcher m = p.matcher(responseSB);
if (m.find()) {
url = m.group(1);
}
p = Pattern.compile("\"title\":(.*?)\",\"thumbnail");
m = p.matcher(responseSB);
if (m.find()) {
description = m.group(1);
}

How to get JSON data using GSON

This has probably been asked before, but I do not know the terminology for my question, therefore do not know what to look up.
I am using GSON and Java trying to get information from a parsed JSONElement.
Java code:
JsonParser parser = new JsonParser();
String url = "https://chapel-logs.herokuapp.com/attendance";
URL obj = new URL(url);
HttpURLConnection con = (HttpURLConnection) obj.openConnection();
// optional default is GET
con.setRequestMethod("GET");
//add request header
con.setRequestProperty("Accept", "application/json");
int responseCode = con.getResponseCode();
System.out.println("\nSending 'GET' request to URL : " + url);
System.out.println("Response Code : " + responseCode);
BufferedReader in = new BufferedReader(
new InputStreamReader(con.getInputStream()));
String inputLine;
StringBuffer response = new StringBuffer();
while ((inputLine = in.readLine()) != null) {
response.append(inputLine);
}
in.close();
//print result
JsonElement element = parser.parse(response.toString());
if (element.isJsonObject()) {
JsonObject albums = element.getAsJsonObject();
System.out.println(albums.get("students")); //prints out data in students
System.out.println(albums.get("students.LastChapelAttended")); //error
}
My JSON :
{"students":[{"LastChapelAttended":{"Loc":"","Chapel":"WhyChapel","Year":2018,"Month":9,"Day":6,"Hour":15,"Min":14,"Sec":28},"StudNum":"F02660934","Attendance":17},{"LastChapelAttended":{"Loc":"","Chapel":"WhyChapel","Year":2018,"Month":9,"Day":5,"Hour":19,"Min":49,"Sec":11},"StudNum":"002660934","Attendance":2},{"LastChapelAttended":{"Loc":"","Chapel":"WhyChapel","Year":2018,"Month":9,"Day":4,"Hour":20,"Min":35,"Sec":57},"StudNum":"002643472","Attendance":2},{"LastChapelAttended":{"Loc":"","Chapel":"WhyChapel","Year":2018,"Month":9,"Day":7,"Hour":5,"Min":34,"Sec":54},"StudNum":"002664906","Attendance":1}]}
The data I am trying to get is: LastChapelAttended, however LastChapelAttended is within students. In JavaScript the equivalent to what I am trying would be students.LastChapelAttended if that helps.
Thanks in advance!

JsonObject jObj=(JsonObject)albums.get("students").getAsJsonArray().get(0);
System.out.println(jObj.get("LastChapelAttended"));
Get it as a JsonArray and then loop through the array to get LastChapelAttended.

First, students is not an object but an array. Thus students.LastChapelAttended should not work in any language. If you want to retrieve LastChapelAttended of the first student in the array students[0].LastChapelAttended should work.
I am not familiar with gson, but I think what you want to do is something like this:
if (element.isJsonObject()) {
JsonObject albums = element.getAsJsonObject();
JsonArray students = albums.getAsJsonArray("students");
for (JsonElement student : students) {
System.out.println(albums.getAsJsonObject().get("LastChapelAttended"));
}
}

You can check this out for help Difference between JSONObject and JSONArray
Students is a JsonArray
LastChapelAttended is a JSONObject you can get it by calling
json = (json data)
JsonParser parser = new JsonParser();
JsonObject rootObj = parser.parse(json).getAsJsonObject();
JsonArray studentsArray = rootObj.getAsJsonArray("students");
for (JsonElement stu : studentsArray) {
JsonObject student = stu.getAsJsonObject();
JsonObject LastChapelAttended = student.getAsJsonObject("LastChapelAttended");
}

Just iterate over the student array
albums.getAsJsonArray("students")
.forEach(student -> System.out.println(student.getAsJsonObject()
.get("LastChapelAttended")));

Loop all data from json in java

I have a problem with Java when I try to display all of content from cmd's elements. So here is my code:
public static void main(String[] args) throws Exception {
// Json Stream Reader
String jsonS = "";
// Connect to web api
URL url = new URL("http://b50172e8.ngrok.io/api/plugin/521100d075c1284b944841394e157744");
// Make Connection
URLConnection conn = url.openConnection();
conn.setRequestProperty("Accept","*/*");
conn.connect();
// Stream reader
BufferedReader in = new BufferedReader(new InputStreamReader(conn.getInputStream()));
String inputLine;
while((inputLine = in.readLine()) != null) {
jsonS+=inputLine;
}
// Read json response
Gson gson = new Gson();
// Json Object
JsonObject jsonObject= gson.fromJson(jsonS, JsonObject.class);
JsonElement data = jsonObject.get("data");
System.out.println(data);
// Close connection
in.close();
}
Output:
[{"cmd":"cmd-1"},{"cmd":"cmd-2"},{"cmd":"cmd-3"}]
I want to use foreach of cmd to display the following:
cmd-1
cmd-2
cmd-3

Try this code. I hope it helps.
public static void main(String[] args) throws Exception {
// Json Stream Reader
String jsonS = "";
// Connect to web api
URL url = new URL("http://b50172e8.ngrok.io/api/plugin/521100d075c1284b944841394e157744");
// Make Connection
URLConnection conn = url.openConnection();
conn.setRequestProperty("Accept","*/*");
conn.connect();
// Stream reader
BufferedReader in = new BufferedReader(new InputStreamReader(conn.getInputStream()));
String inputLine;
while((inputLine = in.readLine()) != null) {
jsonS+=inputLine;
}
// Read json response
Gson gson = new Gson();
// Json Object
JsonObject jsonObject= gson.fromJson(jsonS, JsonObject.class);
JsonArray data = jsonObject.getAsJsonArray("data");
//here data is JsonArray and it contains everithing: [{"cmd":"cmd-1"},{"cmd":"cmd-1"},{"cmd":"cmd-1"}]
data.forEach(el -> {
//Get Json object which has key and value -> {"cmd":"cmd-1"}
JsonObject jo = el.getAsJsonObject();
//get the value as Json element -> "cmd-1"
JsonElement je = jo.get("cmd");
//Then make the json element string
String value = je.getAsString();
System.out.println(value);
});
//System.out.println(data);
// Close connection
in.close();
}

How do i get, modify and post a json object?

as mentioned in my older topic 3 days ago - Last Topic
i got a json response and changed it to a string. The Json Response represents an User-Object. Within the User-Object i wanted to search for a specific project and delete it. After that, i want to post it again via HttpPost.
private static String getContent(HttpResponse response) {
HttpEntity entity = response.getEntity();
if (entity == null) return null;
BufferedReader reader;
try {
reader = new BufferedReader(new InputStreamReader(entity.getContent()));
String line = reader.readLine();
reader.close();
return line;
} catch (IllegalStateException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
String StringResponse = getContent(JsonResponse);
JSONObject jsonObject = new JSONObject(StringResponse);
JSONArray ProjectsArray= jsonObject.getJSONArray("projects");
Searching for a specific project by saving the attributes in a JsonArray.
ArrayList<Integer> indexesToRemove = new ArrayList<Integer>();
for (int i = 0; i < projectsArray.length; i++) {
JSONObject current = projectsArray.get(i);
if (current.get("projectKey") == "**ProjectName**") {
indexesToRemove.add(i);
}
}
Deleting the project...
for (int i = indexesToRemove.size()-1; i>=0; i--)
{
projectsArray.remove(indexesToRemove.get(i));
}
That works perfect and my searched project is deleted. But the problem is, that i want to post the modified UserObject/String again via HttpPost. And my deleted project is just in my JsonArray "projectsArray" and not in my string from the beginning. I can't post "projectsArray"....
HttpPost UserChange = new HttpPost (TestUserURL+user); //TODO:
UserChange.setHeader("Accept", "application/json");
UserChange.setHeader("Content-type", "application/json");
params = new StringEntity("ModifiedJsonString", HTTP.UTF_8); // How do i get the complete Json string?
UserChange.setEntity(params);
HttpResponse UserChangeResponse = httpclient.execute(UserChange);
HttpEntity entity2 = UserChangeResponse.getEntity();
if (entity2 != null) {
entity2.consumeContent();
}
I need the "ModifiedJsonString", which includes the complete json file from the beginning.
params = new StringEntity(ModifiedJsonString, HTTP.UTF_8);
Best Regards

The following code removes one of the selected project.
String jsonString = "{ \"account\": \"Kpatrick\", \"firstname\": \"Patrick\", \"instances\": [ { \"id\": \"packerer-pool\", \"key\": \"packerer-pool123\", \"userAccount\": \"kpatrick\", \"firstname\": \"Patrick\", \"lastname\": \"Schmidt\" } ], \"projects\": [ { \"id\": \"packerer-projectPool\", \"projectKey\": \"projectPool-Pool\", \"cqprojectName\": \"xxxxx\" }, { \"id\": \"packerer-secondproject\", \"projectKey\": \"projectPool-Pool2\", \"cqprojectName\": \"xxxx\" }, { \"id\": \"packerer-thirdproject\", \"projectKey\": \"projectPool-Pool3\", \"cqprojectName\": \"xxxx\" } ], \"clients\": [], \"dbid\": 76864576, \"version\": 1, \"id\": \"dbpack21\"}";
JSONParser parser = new JSONParser();
JSONObject jsonObject = (JSONObject) parser.parse(jsonString);
ArrayList<String> listOfNodes = new ArrayList<String>();
JSONArray projectArray = (JSONArray) jsonObject.get("projects");
int len = projectArray.size();
if (projectArray != null) {
for (int i = 0; i < len; i++) {
String projectId = ((JSONObject) projectArray.get(i)).get("projectKey").toString();
if (!projectId.equals("projectPool-Pool2")) {
listOfNodes.add(projectArray.get(i).toString());
}
}
}
// Remove the element from arraylist
// Recreate JSON Array
JSONArray jsArray = new JSONArray();
jsArray.addAll(listOfNodes);
jsonObject.remove(projectArray);
jsonObject.put("projects", listOfNodes);
System.out.println(jsonObject.toString());
This for example , prints the following JSON string removing one of the projects.
Once you have this , you can then use this to create a StringEntity and then use it in HTTPPost calls. Hope it helps

How to read resulting JSON data into Java ?

I am trying to read results of a JSON request into java, yet
The partial output of my JSON request looks like this :
"route_summary": {
"total_distance": 740,
"total_time": 86,
"start_point": "Marienstraße",
"end_point": "Feldbergstraße"
}
I would like to use the standard json library to extract the values in total_distance.
However I only seem to be able to get the 'route_summary' by doing this :
JSONObject json = null;
json = readJsonFromUrl(request);
json.get("route_summary");
Where
public static JSONObject readJsonFromUrl(String url) throws IOException, JSONException {
InputStream is = new URL(url).openStream();
try {
BufferedReader rd = new BufferedReader(new InputStreamReader(is, Charset.forName("UTF-8")));
String jsonText = readAll(rd);
JSONObject json = new JSONObject(jsonText);
return json;
} finally {
is.close();
}
}
What I want is get 'into' route_summary, any clue / tip would be great !

You need to get route_summary, as you already did, and from that object you need to get the total_distance. This will give you back the route_summary.total_distance.
Code sample:
JSONObject object = new JSONObject(s);
int totalDistance = object.getJSONObject("route_summary").getInt("total_distance");

I would recommend you to use GSON library. You can create class which will represent the message and then automatically map JSON to object by invoking function: gson.fromJson(message, YourMessageClass.class).getRoute_summary().
Here is the example of such approach: https://sites.google.com/site/gson/gson-user-guide/#TOC-Object-Examples