I'm going to parse a json array from web server to android app.The array looks like this
{"Level":
[
{"route":[{"lat":38.889762,"lgn":-77.081764},
{"lat":38.89096,"lgn":-77.081916}]},
{"route":[{"lat":38.889762,"lgn":-77.081764},
{"lat":38.89096,"lgn":-77.081916}]},
{"route":[{"lat":38.889762,"lgn":-77.081764},
{"lat":38.89096,"lgn":-77.081916}]}
]
}
my java code is
JSONObject json = new JSONObject(result);
JSONArray jArray = json.getJSONArray("Level");
rlevel = new ArrayList<LatLng>();
System.out.println("*****JARRAY*****"+jArray.length());
for(int i=0;i<jArray.length();i++){
JSONObject json_data = jArray.getJSONObject(i);
jlat = json_data.getDouble("lat");
jlgn = json_data.getDouble("lgn");}
but not works! any idea?after this i want to save each route into an array (etc $plan[1]=first route from json, $plan[2]=second route from json)
Try something like this:
//code is a String where you saved the json
JSonObject json= new JsonParser().parse(code).getAsJsonObject();
JsonArray jArray= json.getAsJsonArray("Level");
rLevel=new ArrayList<LatLng>();
//notice the use of the size() method. There is not length() method defined for ArrayList
System.out.println("*****JARRAY*****"+jArray.size());
for(int i=0;i<jArray.size();i++){
//notice that inside the Level Array you have route-arrays
JSonObject level_item = jArray.get(i).getAsJsonObject();
JSonArray route= level_item.getAsJSonArray("route");
//now I don't know exactly what data you want to extract, since there are 2
//pairs of LatLng, for the first one:
jlat = route.get(0).get("lat").getAsDouble();
jlgn= route.get(0).get("lgn").getASDouble();
The exact names for methods and JsonObjects tend to differ from a library to another, but the principle is the same.
This parse task can be done very easily using droidQuery:
try {
JSONObject json = $.parseJSON(result);
if (json.has("Level")) {
Object[] datas = $.makeArray(json.getJSONArray("Level"));
for (Object data : datas) {
JSONObject obj = (JSONObject) data;
Object[] coordinates = $.makeArray(obj.getJSONArray("route"));
for (Object coord : coordinates) {
Map<String, ?> map = $.map((JSONObject) coord);
double latitude = (Double) map.get("lat");
double longitude = (Double) map.get("lgn");
//TODO: do something with these values
}
}
}
else {
Log.d("JSON", "Result does not contain 'Levels' variable");
}
}
catch (Throwable t) {
t.printStackTrace();
}
Related
#Override
protected void onPostExecute(String response) {
String firstName = null;
String lastName = null;
try {
JSONObject jsonResponse = new JSONObject(response);
JSONArray jsonArray = jsonResponse.getJSONArray("");
JSONObject userInfo = jsonArray.getJSONObject(0);
firstName = userInfo.getString("id");
lastName = userInfo.getString("id");
}
catch (JSONException e){
e.printStackTrace();
}
I have this JSON file https://api.myjson.com/bins/1a5t7w
How i can acces to thats values, i used this code but it doesn`t work?
It returns #null#
You are getting a JSON array in the response.
To parse this array you need to pass the response to JSONArray object like below
try {
JSONArray rspArr = new JSONArray(response);
for(int i= 0; i< rspArr.length(); i++){
JSONObject jsonObject = (JSONObject) rspArr.get(i);
//Your logic
}
}catch (Exception e ){
//log exception
}
// since you know is an array, create a JSONArray based on your response String
JSONArray array = JSONArray(response)
// obtain the first element of your array as a JSONObject
JSONObject jsonObject = array.getJSONObject(0)
// once you get the jsonObject you can start getting the values you need
String id = jsonObject.getString("id")
Hope it helps!
Answer by Arunangshu seems correct, you need to extract the JSONArray first because the API is returning JSONArray(array of JSON objects) and not one big JSON object.
One can use http://jsonviewer.stack.hu/ for viewing JSON. It gives better understanding of the JSON structure.
For Java, one can use http://www.jsonschema2pojo.org/ for converting JSON object(not array) to Java Pojo class (select the options carefully).
Following is the first object from json array -
{"id":48191,"title":"Apple Crumble Recipe","image":"https://spoonacular.com/recipeImages/48191-312x231.jpg","imageType":"jpg","usedIngredientCount":1,"missedIngredientCount":2,"missedIngredients":[{"id":4073,"amount":35.0,"unit":"g","unitLong":"grams","unitShort":"g","aisle":"Milk, Eggs, Other Dairy","name":"margarine","original":"35 g margarine or butter","originalString":"35 g margarine or butter","originalName":"margarine or butter","metaInformation":[],"meta":[],"image":"https://spoonacular.com/cdn/ingredients_100x100/butter-sliced.jpg"},{"id":8120,"amount":35.0,"unit":"g","unitLong":"grams","unitShort":"g","aisle":"Cereal","name":"rolled oats","original":"35 g rolled oats","originalString":"35 g rolled oats","originalName":"rolled oats","metaInformation":[],"meta":[],"image":"https://spoonacular.com/cdn/ingredients_100x100/rolled-oats.jpg"}],"usedIngredients":[{"id":9003,"amount":400.0,"unit":"g","unitLong":"grams","unitShort":"g","aisle":"Produce","name":"apples","original":"400 g cooking apples peeled cored and quartered","originalString":"400 g cooking apples peeled cored and quartered","originalName":"cooking apples peeled cored and quartered","metaInformation":["cored","peeled","quartered"],"meta":["cored","peeled","quartered"],"image":"https://spoonacular.com/cdn/ingredients_100x100/apple.jpg"}],"unusedIngredients":[],"likes":965}
Very new to JSON, this is probably very simple but I'm not sure how to access the "coordinates" in this JSON I know how to go from resourceSets to resources but get stuck at "point":
{
"resourceSets":[
{
"estimatedTotal":1,
"resources":[
{
"__type":"Location:http:\/\/schemas.microsoft.com\/search\/local\/ws\/rest\/v1",
"bbox":[
51.3223903,
-0.2634519,
51.3246386,
-0.2598541
],
"name":"name",
"point":{
"type":"Point",
"coordinates":[
51.3235145,
-0.261653
]
}
}
]
}
]
}
My code so far:
JSONParser parser = new JSONParser();
JSONObject jObj = (JSONObject)parser.parse(result);
JSONArray jsonArray = (JSONArray)jObj.get("resourceSets");
for (int i = 0; i < jsonArray.size(); i ++) {
JSONObject jObjResourceSets = (JSONObject)jsonArray.get(i);
JSONArray jsonArray2 = (JSONArray)jObjResourceSets.get("resources");
System.out.println("Coords" + jObjResourceSets.get("point"));
}
Lets analyse what you're doing (and need to be doing), step by step, in order to get the "coordinates".
First of all, JSON is a great language to transfer static data. It works like a dictionary, where you have a key and the respective value. The key should always be a String, but the value can be a String, an int/double or even an array of other JSON objects. That's what you have.
For instance, "estimatedTotal" is an element (JSONObject) from the "resourceSet" array (JSONArray).
JSONArray jsonArray = (JSONArray)jObj.get("resourceSets");
What you're saying here is straight forward: from your overall JSONObject - jObj - you want to extract the array with key "resourceSets".
Now you have direct access to "resourceSets" array elements: "estimatedTotal", "resources", etc. So, by applying the same logic, in order to access "coordinates" we need to access the "resources" array. And by that I mean to create a JSONArray object like we did before.
JSONArray jsonResourcesArray = (JSONArray)jObjResourceSets.get("resources");
I hope it's clear what's the content of jsonResourcesArray here. It's the JSON array of "__type", "bbox", "name", "point", (...). The Coordinates howevere are inside "point" JSON object. How do we access it?
JSONObject jsonPointObject = (JSONObject) jsonResourcesArray.get("point");
And you know by know that "jsonPointObject" has as its values the following JSON objects: "type" and "coordinates". Coordinates is an array of values, so do we have to use JSONArray or JSONObject?
JSONArray jsonCoordinatesArray = (JSONArray) jsonPointObject.get("coordinates");
From which we mean: from the jsonPointObject we want to extract the array that has key "coordinates". Now your array is a JSONArray with values of jsonCoordinatesArray.get(0) and jsonCoordinatesArray.get(0).
Now you have, not only the code to get those values, but the understanding of how JSON works and how Java interacts with it so you can solve any Json problem from now on.
Normally this code works for the given JSON object. However I'll put the tested formatted JSON value below the java code so you can test it as well.
Note that this code will get you all the coordinates of all the elements in your object.
public static void main(String[] args) throws Exception {
String result = getJsonString();
// Getting root object
JSONParser parser = new JSONParser();
JSONObject jObj = (JSONObject)parser.parse(result);
// Getting resourceSets Array
JSONArray jsonArray = (JSONArray)jObj.get("resourceSets");
for (int i = 0; i < jsonArray.size(); i++) {
// Getting the i object of resourceSet
JSONObject jObjResourceSets = (JSONObject) jsonArray.get(i);
// Getting resources list of the current element
JSONArray jsonArray2 = (JSONArray) jObjResourceSets.get("resources");
for (int j = 0; j < jsonArray2.size(); j++) {
// Getting the j resource of the resources array
JSONObject resource = (JSONObject) jsonArray2.get(j);
// Getting the point object of the current resource
JSONObject point = (JSONObject) resource.get("point");
// Getting the coordinates list of the point
JSONArray coordinates = (JSONArray) point.get("coordinates");
for (int k = 0; k < coordinates.size(); k++) {
System.out.println("Coordinates[" + k + "]: " + coordinates.get(k));
}
// Printing an empty line between each object's coordinates
System.out.println();
}
}
}
The tested JSON Object:
{
"resourceSets":[
{
"estimatedTotal":1,
"resources":[
{
"__type":"Location:http:\/\/schemas.microsoft.com\/search\/local\/ws\/rest\/v1",
"bbox":[
51.3223903,
-0.2634519,
51.3246386,
-0.2598541
],
"name":"name",
"point":{
"type":"Point",
"coordinates":[
51.3235145,
-0.261653
]
}
}
]
}
]
}
If it worked please mark it as the answer.
Good luck ^^
B.
You need the following piece of code to get the data.
JSONArray jsonArray2 = (JSONArray)jObjResourceSets.get("resources");
/**
* here we should note that the "resources" is only having one JSON object hence we can take it as below
* from 0th index using ((JSONObject)jsonArray2.get(0)) these piece of code and the next part is to take the point JSONObject
* from the object.
*/
JSONObject temp = (JSONObject)((JSONObject)jsonArray2.get(0)).get("point");
System.out.println("Coords"+temp.get("coordinates")); //this will give you the coordinates array
//now if you want to do further processing, traverse in the jsonArray like below
JSONArray arr= (JSONArray)temp.get("coordinates");
System.out.println("X coordinate:"+arr.get(0));
System.out.println("Y coordinate:"+arr.get(1));
For more information and further details on JSONObject and JSONArray you can go through this linkparsing-jsonarray-and-jsonobject-in-java-using-json-simple-jar
json-simple-example-read-and-write-json
I have following JSONObject (not array, which I don't mind to convert). I am trying to do two things:
get the count of genre entry as "poetry" (count = 2).
get the key value of author name and genre:
authorName = malcolm
genreName = newsarticle
authorName = keats
genreName = poetry
{ "AddressBook" :{
"Details" :{
"authorname" :{
"Author-malcolm":{
"genre" :"poetry"
}
"Author-keats":{
"genre" :"poetry"
}
}
}
}
}
Code which I tried:
public static void main(String[] args) throws Exception, IOException, ParseException {
JSONParser parser = new JSONParser();
Object obj = parser.parse(new FileReader("My path to JSON"));
JSONObject jsonObject = (JSONObject) obj;
JSONArray arrayhere = new JSONArray();
arrayhere.add(obj);
System.out.println(arrayhere);
int count = 0;
for(int i = 0; i < arrayhere.size(); i++) {
JSONObject element = arrayhere.getJSONObject(i);//The method getJSONObject(int) is undefined for the type JSONArray
String branchName = element.getString("genre");//The method getString(String) is undefined for the type JSONObject
if(branchName.equals("poetry")) {
count ++;
}
}
System.out.println("Count f0r poetry genre=" + count);
}
}
I have looked at solutions all over. There is no question similar to this at stackoverflow. I am not sure if the procedure is correct.
A few problems here.
First, I'm not sure where you got that example JSON but you can't work with that. That's not even valid JSON Formatting.
Looks like you want something like this:
{
AddressBook:
[
{
authorname: "author-malcom",
genre:"poetry"
},
{
authorname: "author-keats",
genre: "poetry"
}
]
}
That's the structure you're trying to create in JSON.
So, you're parsing this in from a file into a JSONObject that has a key called AddressBook inside of it. That key points to an array of JSONObjects representing authors. Each of those objects will have a key called genre. You're trying to access the genre key and count on a condition.
What you did above was create attempt to create a JSONObject from an invalid string, and then add the entire JSONObject itself into the JSONArray. JSONArray.add() doesn't convert an object to an array, it literally adds it onto the array.
jsonObj => {"Name":"name1","Id":1000}
jsonArray.add(jsonObj)
jsonArray => [{"Name":"name1","Id":1000}]
That's what you did in your code above. You didn't create an array from a JSONObject, you added an object to the array.
Proper use is going to look like:
Object obj = parser.parse(new FileReader("path_to_file"));
JSONObject jobj = (JSONObject) obj;
//access key AddressBook
JSONArray author_array = jobj.getJSONArray("AddressBook");
int poetry = 0;
for(int i = 0; i < author_array.length(); i++) {
JSONObject author = (JSONObject) author_array.get(i);
if(author.getString("genre").equals("poetry")) {
poetry++;
}
}
To summarize, you're problems come from a lack of understanding about JSON Formatting and how to access elements within a JSON Object.
Paste in the sample JSONObject I gave you above here. That site will let you visualize what you're working with.
So I have some code that is able to send this out:
{"id":1,
"method":"addWaypoint",
"jsonrpc":"2.0",
"params":[
{
"lon":2,
"name":"name",
"lat":1,
"ele":3
}
]
}
The server receives this JSON object as a string named "clientstring":
JSONObject obj = new JSONObject(clientstring); //Make string a JSONObject
String method = obj.getString("method"); //Pulls out the corresponding method
Now, I want to be able to get the "params" value of {"lon":2,"name":"name","lat":1,"ele":3} just like how I got the "method".
however both of these have given me exceptions:
String params = obj.getString("params");
and
JSONObject params = obj.getJSONObject("params");
I'm really at a loss how I can store and use {"lon":2,"name":"name","lat":1,"ele":3} without getting an exception, it's legal JSON yet it can't be stored as an JSONObject? I dont understand.
Any help is VERY appreciated, thanks!
params in your case is not a JSONObject, but it is a JSONArray.
So all you need to do is first fetch the JSONArray and then fetch the first element of that array as the JSONObject.
JSONObject obj = new JSONObject(clientstring);
JSONArray params = obj.getJsonArray("params");
JSONObject param1 = params.getJsonObject(0);
How try like that
JSONObject obj = new JSONObject(clientstring);
JSONArray paramsArr = obj.getJSONArray("params");
JSONObject param1 = paramsArr.getJSONObject(0);
//now get required values by key
System.out.println(param1.getInt("lon"));
System.out.println(param1.getString("name"));
System.out.println(param1.getInt("lat"));
System.out.println(param1.getInt("ele"));
Here "params" is not an object but an array. So you have to parse using:
JSONArray jsondata = obj.getJSONArray("params");
for (int j = 0; j < jsondata.length(); j++) {
JSONObject obj1 = jsondata.getJSONObject(j);
String longitude = obj1.getString("lon");
String name = obj1.getString("name");
String latitude = obj1.getString("lat");
String element = obj1.getString("ele");
}
Trying to parse multi-level JSON in Java.
Having JSON input in format like this:
{"object1":["0","1", ..., "n"],
"objects2":{
"x1":{"name":"y1","type":"z1","values":[19,20,21,22,23,24]}
"x2":{"name":"y2","type":"z2","values":[19,20,21,22,23,24]}
"x3":{"name":"y3","type":"z1","values":[19,20,21,22,23,24]}
"x4":{"name":"y4","type":"z2","values":[19,20,21,22,23,24]}
}
and need to get all objects from 2 by one of the attributes, e.g. get all objects with type = z1.
Using org.json*.
Tried to do something like this:
JSONObject GeneralSettings = new JSONObject(sb.toString()); //receiving and converting JSON;
JSONObject GeneralObjects = GeneralSettings.getJSONObject("objects2");
JSONObject p2;
JSONArray ObjectsAll = new JSONArray();
ObjectsAll = GeneralObjects.toJSONArray(GeneralObjects.names());
for (int i=0; i < GeneralObjects.length(); i++){
p2 = ObjectsAll.getJSONObject(i);
switch (p2.getString("type")) {
case "z1": NewJSONArray1.put(p2); //JSON array that should contain values with type z1.
break;
case "z2": NewJSONArray2.put(p2); //JSON array that should contain values with type z2.
default: System.out.println("error");
break;
}
}
}
But getting null pointer exception and overall method seems not to be so well.
Please advise, is there any way to make it easier or, what am I doing wrong?
If you're getting a NullPointerException it's most likely that you haven't initialized NewJSONArray1 and NewJSONArray2.
You didn't include their declaration, but you probably just need to do
NewJSONArray1=new JSONArray();
NewJSONArray2=new JSONArray();
before your loop.
Aside: by convention java variables should start with a lower case letter, e.g. newJSONArray1
public static void main(String[] args) {
String s =
"{\"object1\":[\"0\",\"1\",\"n\"]," +
"\"objects2\":{" +
"\"x1\":{\"name\":\"y1\",\"type\":\"z1\",\"values\":[19,20,21,22,23,24]}," +
"\"x2\":{\"name\":\"y2\",\"type\":\"z2\",\"values\":[19,20,21,22,23,24]}," +
"\"x3\":{\"name\":\"y3\",\"type\":\"z1\",\"values\":[19,20,21,22,23,24]}," +
"\"x4\":{\"name\":\"y4\",\"type\":\"z2\",\"values\":[19,20,21,22,23,24]}" +
"}}";
System.out.println(s);
JSONObject json = new JSONObject(s);
JSONObject object2 = json.optJSONObject("objects2");
if (object2 == null) {
return;
}
JSONArray result = new JSONArray();
for (Object key : object2.keySet()) {
JSONObject object = object2.getJSONObject(key.toString());
String type = object.optString("type");
if ("z1".equals(type)) {
System.out.println(object.toString());
result.put(object);
}
}
System.out.println(result);
}
You can always convert it to string and use json-path:
https://code.google.com/p/json-path/