Develop Reference

Easiest way to parse a triple nested JSON?

I am given a JSON that will come in this format:
"template":{
"mod1":[
{
"param1":"55",
"param2":"5",
"param3":"somedata"
}
],
"mod2":[
{
"param1":"somedata",
"param2":"somedata"
}
],
"mod3":[
{
"param1":"somedata",
"param2":"somedata",
"param3":"somedata"
}
],
"mod4":[
{
"param1":"somedata",
"param2":"somedata"
}
],
"mod5":[
{
"param1":"somedata"
}
]
}
}
What is the easiest way to parse it? What I'd like is to get the params inside the mod and their associated values together, to store into a database. The way I am doing it is as so:
JSONObject obj = new JSONObject(json);
System.out.println(obj);
Iterator<String> keys = obj.keys();
while(keys.hasNext()) {
String key = keys.next();
JSONObject currTemplate = (JSONObject) obj.get(key);
if(currTemplate instanceof JSONObject) {
System.out.println("LIST OF ALL MODULES : " + currTemplate);
Iterator<String> currObjKeys = ((JSONObject) currTemplate).keys();
while(currObjKeys.hasNext()) {
String currObjKey = currObjKeys.next();
System.out.println("MODULE: " + currObjKey);
JSONArray array = currTemplate.getJSONArray(currObjKey);
System.out.println("ARRAY: " + array);
for(int i = 0; i < array.length(); i++){
JSONObject object = array.getJSONObject(i);
String[] names = JSONObject.getNames(object);
for(String name: names) {
System.out.println("PARAMS");
System.out.println(name);
System.out.println(object.get(name));
}
}
}
}
And it currently prints what I need correctly. What I am asking is if there is a more efficient way to do it - the way I currently have it is O(N^4), and I was wondering if anyone had any idea to parse the JSON in a more efficient way. Note: the params will not always be in form param1, param2, the names will always be different. Just changed it for confidentiality sake.
Thank you in advance.

count key value in JSON and extract values

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.

Loop through JSON to get certain values

I need to loop through a JSON and get the following information:
The original title, overview, release date, poster_path.
I have the following code..
#Override
protected void onPostExecute(String s) {
try {
JSONObject jsonObject = new JSONObject(result);
JSONArray jArray = jsonObject.getJSONArray("results");
JSONObject json_data = null;
for (int i = 0; i < jArray.length(); i++) {
JSONObject finalObject = jArray.getJSONObject(i);
String movie_title = finalObject.getString("title");
String releaseDate = finalObject.getString("release_date");
mMovie_title.setText(movie_title);
mReleaseDate.setText(releaseDate);
}
super.onPostExecute(s);
} catch (JSONException e) {
e.printStackTrace();
}
}
The problem with this code is that it only gets me the final movie in the array.
It does not print any other movie titles out.
What I need to do is fetch the movie titles from the JSON along with the overview, release dates & poster path.
Here is the JSON.. https://api.themoviedb.org/3/movie/top_rated?api_key=f1d314280284e94ff7d1feeed7d44fdf&language=en-US&page=1
Any help is much appreciated.

mMovie_title.setText(movie_title);
mReleaseDate.setText(releaseDate);
It looks like you are re-assigning the same variable everytime. That's why you only get the last element.
You should probably have a StringBuilder
StringBuilder titles = new StringBuilder();
for ... {
...
titles.append(movie_title);
}
mMovie_title.setText(titles.toString());

It's not a good decision to loop the JSON.
Try to use GSON
The performance is better than that and also it's a very good practice
Gson is a Java library that can be used to convert Java Objects into their JSON representation. It can also be used to convert a JSON string to an equivalent Java object.
Nice coding!

If you want to store multiple movie titles then you need a few things.
First, you need a movie object to hold the values of the movie titles and the movie dates. Something like:
public class Movie {
private String movieTitle;
private String releaseDate;
public Movie(String movieTitle, String releaseDate) {
super();
this.movieTitle = movieTitle;
this.releaseDate = releaseDate;
}
}
Then you need to have a list of movies.
super.onPostExecute(s);
List<Movie> movies = new ArrayList<Movie>();
Movie movie = null;
try {
JSONObject jsonObject = new JSONObject(result);
JSONArray jArray = jsonObject.getJSONArray("results");
JSONObject json_data = null;
for (int i = 0; i < jArray.length(); i++)
JSONObject finalObject = jArray.getJSONObject(i);
String movie_title = finalObject.getString("title");
String releaseDate = finalObject.getString("release_date");
movies.add(new Movie(movie_title, releaseDate));
}
} catch (JSONException e) {
e.printStackTrace();
}
// Do something with movies
// example ::
for (Movie movie : movies) {
textView.setText(movie.getMovieTitle); // etc...
}

get value by key jsonarray

JSONArray arr =
[
{"key1":"value1"},
{"key2":"value2"},
{"key3":"value3"},
{"key4":"value4"}
]
arr.get("key1") throws error. How can I get the value by key in JSONArray?
arr.getString("key1") also throws error. Should I loop through the array? Is it the only way to do it?
What is the error?
In Eclipse Debug perspective, these expressions returns as; error(s)_during_the_evaluation

You can parse your jsonResponse like below code :
private void parseJsonData(String jsonResponse){
try
{
JSONArray jsonArray = new JSONArray(jsonResponse);
for(int i=0;i<jsonArray.length();i++)
{
JSONObject jsonObject1 = jsonArray.getJSONObject(i);
String value1 = jsonObject1.optString("key1");
String value2 = jsonObject1.optString("key2");
String value3 = jsonObject1.optString("key3");
String value4 = jsonObject1.optString("key4");
}
}
catch (JSONException e)
{
e.printStackTrace();
}
}

Sounds like you want to find a specific key from an array of JSONObjects. Problem is, it's an array, so you have to iterate over each element. One solution, assuming no repeat keys is...
private Object getKey(JSONArray array, String key)
{
Object value = null;
for (int i = 0; i < array.length(); i++)
{
JSONObject item = array.getJSONObject(i);
if (item.keySet().contains(key))
{
value = item.get(key);
break;
}
}
return value;
}
Now, let's say you want to find the value of "key1" in the array. You can get the value using the line: String value = (String) getKey(array, "key1"). We cast to a string because we know "key1" refers to a string object.

for (int i = 0; i < arr.length(); ++i) {
JSONObject jsn = arr.getJSONObject(i);
String keyVal = jsn.getString("key1");
}
You need to iterate through the array to get each JSONObject. Once you have the object of json you can get values by using keys

You can easy get a JSON array element by key like this:
var value = ArrName['key_1']; //<- ArrName is the name of your array
console.log(value);
Alternatively you can do this too:
var value = ArrName.key_1;
That's it!

How to convert JSON formatted string of data rows of a table in to java array in android

I have a JSON string like this of data for a table in an android app. one of {} is a row of data for the table. I want to separate these {}s into an array and then each element inside this array into other sub-arrays separating other elements inside {}. Please suggest an appropriate way of accomplishing this criteria using JSON. Thank you.
[
{
"nodeName":"prime_mtsc22#smpp3",
"nodeId":"MTSC3",
"tidPrefix":"4",
"optStatus":"offline",
"daStart":"1",
"daEnd":"3",
"description":"Description"
},
{
"nodeName":"prime_mtsc22#smpp2",
"nodeId":"MTSC58",
"tidPrefix":"1",
"optStatus":"blocked",
"daStart":"5",
"daEnd":"10",
"description":"new description"
},
{
"nodeName":"prime_mtsc22#smpp1",
"nodeId":"MTSC1",
"tidPrefix":"15",
"optStatus":"online",
"daStart":"12",
"daEnd":"20",
"description":"Description"
},
{
"nodeName":"prime_mtsc22#smpp0",
"nodeId":"MTSC15",
"tidPrefix":"15",
"optStatus":"offline",
"daStart":"25",
"daEnd":"30",
"description":"Description"
}
]

ok so in that case the code to use is this
String jsonString = <your jsonString>;
// THIS IS NOT NEEDED ANYMORE
//JSONObject json = new JSONObject(jsonString);
JSONArray topArray = null;
try {
// Getting your top array
// THIS IS NOT NEEDED ANYMORE
//topArray = json.getJSONArray(jsonString);
//use this instead
topArray = new JSONArray(jsonString);
// looping through All elements
for(int i = 0; i < topArray.length(); i++){
JSONObject c = topArray.getJSONObject(i);
//list holding row data
List<NodePOJO> nodeList = new ArrayList<NodePOJO>();
// Storing each json item in variable
String nodeName = c.getString("nodeName");
String nodeID = c.getString("nodeID");
NodePOJO pojo = new NodePOJO();
pojo.setNodeName(nodeName);
//add rest of the json data to NodePOJO class
//the object to list
nodeList.add(pojo);
}
} catch (JSONException e) {
e.printStackTrace();
}
ok?

Use JSONObject for this http://developer.android.com/reference/org/json/JSONObject.html
Example
String jsonString = <your jsonString>;
JSONObject json = new JSONObject(jsonString);
JSONObject topArray = ;
try {
// Getting your top array
topArray = json.getJSONArray(TAG_ARRAY_TOP);
// looping through All elements
for(int i = 0; i < topArray.length(); i++){
JSONObject c = topArray.getJSONObject(i);
//list holding row data
List<NodePOJO> nodeList = new ArrayList<NodePOJO>();
// Storing each json item in variable
String nodeName = c.getString("nodeName");
String nodeID = c.getString("nodeID");
NodePOJO pojo = new NodePOJO();
pojo.setNodeName(nodeName);
//add rest of the json data to NodePOJO class
//the object to list
nodeList.add(pojo);
}
} catch (JSONException e) {
e.printStackTrace();
}
Use the NodePOJO class to hold each row values.
public class NodePOJO {
private String nodeName;
// do for rest of the json row data
public void setNodeName(String nodeName) {
this.nodeName = nodeName;
}
public String getNodeName() {
return this.nodeName;
}
}