I am using the following library to parse an object:
{"name": "web", "services": []}
And the following code
import com.json.parsers.JSONParser;
JSONParser parser = new JSONParser();
Object obj = parser.parseJson(stringJson);
when the array services is empty, it displays the following error
#Key-Heirarchy::root/services[0]/ #Key:: Value is expected but found empty...#Position::29
if the array services has an element everything works fine
{"name": "web", "services": ["one"]}
How can I fix this?
Thanks
Try using org.json.simple.parser.JSONParser
Something like this:
JSONParser parser = new JSONParser();
JSONObject jsonObject = (JSONObject) parser.parse(stringJson);
Now to access the fields, you can do this:
JSONObject name = jsonObject.get("name"); //gives you 'web'
And services is a JSONArray, so fetch it in JSONArray. Like this:
JSONArray services = jsonObject.get("services");
Now, you can iterate through this services JSONArray as well.
Iterator<JSONObject> iterator = services.iterator();
// iterate through json array
while (iterator.hasNext()) {
// do something. Fetch fields in services array.
}
Hope this would solve your problem.
Why do you need parser?
try this:-
String stringJson = "{\"name\": \"web\", \"services\": []}";
JSONObject obj = JSONObject.fromObject(stringJson);
System.out.println(obj);
System.out.println(obj.get("name"));
System.out.println(obj.get("services"));
JSONArray arr = obj.getJSONArray("services");
System.out.println(arr.size());
I solve the problen with https://github.com/ralfstx/minimal-json
Reading JSON
Read a JSON object or array from a Reader or a String:
JsonObject jsonObject = JsonObject.readFrom( jsonString );
JsonArray jsonArray = JsonArray.readFrom( jsonReader );
Access the contents of a JSON object:
String name = jsonObject.get( "name" ).asString();
int age = jsonObject.get( "age" ).asInt(); // asLong(), asFloat(), asDouble(), ...
Access the contents of a JSON array:
String name = jsonArray.get( 0 ).asString();
int age = jsonArray.get( 1 ).asInt(); // asLong(), asFloat(), asDouble(), ...
Related
I want to get only a specific value out of all the nested objects. In the application I just need the msg 3 which is inside another object messages.
I have tried it using JSONObject but it is not working for nested object. However It is working with just a single object means root object .
INPUT - {"name":"lola","messages":{"msg 1":"msg 2","msg 3":"msg 4"},"age":22}
String s = sc.nextLine();
JSONParser parser = new JSONParser();
JSONObject json = (JSONObject) parser.parse(s);
System.out.println(json);
Object name = json.get("messages");
System.out.println(name);
JSONObject messageObject = (JSONObject) json.get("messages");
System.out.println(employeeObject);
//Get employee first name
String msg= (String) messageObject.get("msg3");
System.out.println(msg);
The Output:
{"msg 3":"msg 4","msg 1":"msg 2"}
{"msg 3":"msg 4","msg 1":"msg 2"}
null
The last nested object is not fetching in any way. Another thing is that the normal print of the string as a JSONObject gets changed. like the msg3 came before msg1.
In place of null - msg4 should be there.
Thanks in advance.
You are missing a space between "msg" and "3". By the way - you can do this easier, as such.
String s = sc.nextLine();
JSONParser parser = new JSONParser();
JSONObject json = (JSONObject) parser.parse(s);
System.out.println(json);
System.out.println(json.get("message").get("msg 3"));
I have created a .json file:
{
"numbers": [
{
"natural": "10",
"integer": "-1",
"real": "3.14159265",
"complex": {
"real": 10,
"imaginary": 2
},
"EOF": "yes"
}
]
}
and I want to parse it using Json Simple, in order to extract the content of the "natural" and the "imaginary".
This is what I have written so far:
JSONParser parser = new JSONParser();
Object obj = parser.parse(new FileReader("...")); //the location of the file
JSONObject jsonObject = (JSONObject) obj;
String natural = (String) jsonObject.get("natural");
System.out.println(natural);
The problem is that the value of natural is "null" and not "10". Same thing happens when I write jsonObject.get("imaginary").
I have looked at many websites (including StackOverflow), I have followed the same way most people have written, but I am unable to fix this problem.
You need to find the JSONObject in the array first. You are trying to find the field natural of the top-level JSONObject, which only contains the field numbers so it is returning null because it can't find natural.
To fix this you must first get the numbers array.
Try this instead:
JSONParser parser = new JSONParser();
Object obj = parser.parse(new FileReader("...")); //the location of the file
JSONObject jsonObject = (JSONObject) obj;
JSONArray numbers = (JSONArray) jsonObject.get("numbers");
for (Object number : numbers) {
JSONObject jsonNumber = (JSONObject) number;
String natural = (String) jsonNumber.get("natural");
System.out.println(natural);
}
The object in your file has exactly one property, named numbers.
There is no natural property.
You probably want to examine the objects inside that array.
Adding on to #Jermey Hanion's answer and comment, here is what I did to get "imaginary" and "natural"
JSONParser parser = new JSONParser();
Object obj = parser.parse(new FileReader("...")); //the location of the file
JSONObject jsonObject = (JSONObject) obj;
JSONArray numbers = (JSONArray) jsonObject.get("numbers");
for (Object number : numbers) {
JSONObject jsonNumber = (JSONObject) number;
String natural = (String) jsonNumber.get("natural");
JSONObject complex = (JSONObject) jsonNumber.get("complex");
String imaginary = (String) complex.get("imaginary");
System.out.println(natural);
}
Jeremey's answer for getting imaginary is not correct, or maybe it was correct. The above snippet is to my knowledge working on my project.
PS. Sorry for reviving the thread but I thought it would be a useful resource for people looking to learn JSON.simple
I am a newbie to json parsing, I have grabbed a json string from a request and now I need to parse it with java. I'm using simple-lib for this. But I'm really stuck as I'm not familiar with it. I need to extract following data
I used following java code for that but it's not giving me the result I need, please someone help me...
JSONParser parser = new JSONParser();
try {
Object obj = parser.parse(new FileReader("test.json"));
JSONObject jsonObject = (JSONObject) obj;
JSONArray msg = (JSONArray) jsonObject.get("content");
Iterator<String> iterator = msg.iterator();
while(iterator.hasNext()) {
System.out.println(iterator.next());
}
Sample JSON
{
"status": 200,
"message": "ok",
"timestamp": "2014-05-22T14:29:56.824+03:00",
"pagesCount": 1,
"version": "1.1",
"pages": [
{
"number": 100,
"subpages": [
{
"number": 1,
"timestamp": "2014-05-22T13:41:41.116+03:00",
"content": "text"
},
Something like this perhaps?
JSONParser parser = new JSONParser();
JSONObject jsonObject = (JSONObject) parser.parse(new FileReader("test.json"));
JSONArray pages = (JSONArray) jsonObject.get("pages");
if (pages != null) {
for (Object p : pages) {
JSONObject page = (JSONObject) p;
JSONArray subPages = (JSONArray) page.get("subpages");
if (subPages != null) {
for (Object sp : subPages) {
JSONObject subPage = (JSONObject) sp;
System.err.println(subPage.get("content"));
}
}
}
}
You are requesting for the value that corresponds to the key content from your outermost object, but no such key exists in your sample input. In addition, the only field named content has a string as its value and not a JSON array.
To get at the content field you would need to walk the object hierarchy until you reach the element that you need, using something along these lines:
JSONParser parser = new JSONParser();
JSONObject json = (JSONObject) parser.parse(new FileReader("test.json"));
JSONArray pages = (JSONArray) json.get("pages");
// Page 10
JSONObject page = (JSONObject) pages.get(10);
// Subpages of page 10
JSONArray subpages = (JSONArray) page.get("subpages");
// Subpage 7 of page 10
JSONObject subpage = (JSONObject) subpages.get(10);
// Content of subpage 7 of page 10
String content = (String) subpage.get("content");
Please note that I am assuming that e.g. index 10 corresponds to page 10. That may not be true in your case; pages may not be zero-indexed, there may be missing pages or they may not be in the correct order. In that case you will have to iterate over the page and subpage lists and test the value of the number field to find the object that you need.
In any case, if you are indeed using json-simple, as seems to be the case, then JSONObject is a subclass of HashMap and JSONArray a subclass of ArrayList. Therefore, their interfaces should be quite familiar to you.
Disclaimer: Untested code - exception and other error handling removed for brevity
First of all, The json is not valid (if you pasted it complete)
In JSON "{}" is an object, and "[]" is an array, others are just key value pairs.
Simply you can do like this without using parser ,
JSONObject objResponseJSON = new JSONObject(responseJSONString);
int status = (int) objResponseJSON.getInt("status");
//fetch other
JSONArray pages = objResponseJSON.getJSONArray("pages");
for(int count = 0; count < pages.length(); count++){
//fetch other
JSONObject objJSON = pages.getJSONObject(count);
JSONArray subpages = objJSON.getJSONArray("subpages");
for(int count1 = 0; count1 < subpages.length(); count1++){
JSONObject objSubpageJSON = subpages.getJSONObject(count1);
//fetch other
int number = (int) objSubpageJSON.getInt("number");
}
}
I need to create in a Java (Android) a JSONObject/JSONArray with the exact following structure:
{
"listId":
[
"c02bc683-fcd7-47a5-b157-853e26ed099e",
"f8e1c9d7-ae45-4433-a315-726c1d912d09"
]
}
Can somebody help me on this please?
EDIT:
What i have is this:
JSONArray obj = new JSONArray();
JSONObject jsonObject = new JSONObject();
jsonObject.put("listId", folderId);
obj.put(jsonObject);
JSONObject json = new JSONObject();
json.put("id", obj);
But this produces something like:
{
"listId":
[
{"id":"c02bc683-fcd7-47a5-b157-853e26ed099e"},
{"id":"f8e1c9d7-ae45-4433-a315-726c1d912d09"}
]
}
Thanks
You've got your array creation a bit mixed up. What you really want is an object holding an array of string, but what you're doing is creating an array of JSONObject.
Try this instead:
String[] arr = { "c02bc683-fcd7-47a5-b157-853e26ed099e", "f8e1c9d7-ae45-4433-a315-726c1d912d09" };
JSONArray jsonArray = new JSONArray(arr);
JSONObject json = new JSONObject();
json.put("listId", jsonArray);
System.out.println(json); // {"listId":["c02bc683-fcd7-47a5-b157-853e26ed099e","f8e1c9d7-ae45-4433-a315-726c1d912d09"]}
I am using import net.sf.json.JSONObject
My object is like this:
[{
"courseId": "AUTO_CAD",
"strDate": "02-04-2012"
}, {
"courseId": "CNC_PROG",
"strDate": "03-04-2012"
}]
Please help me how to access this in java service
//The code that i have tried.
List<JSONObject> jsonList = new ArrayList<JSONObject>();
jsonList = (List<JSONObject>) context.get("courseData"); // courseDate is my json object
JSONObject obj = jsonList.get(0);
Debug.log("courseStartDate ="+ obj.getJSONObject("courseId"));
//Using this gives me the following error. org.ofbiz.webapp.event.EventHandlerException: Service invocation error (java.lang.String cannot be cast to net.sf.json.JSONObject)
Have not tested yet the code, but worth a try:
JSONArray courses = new JSONArray(json);
JSONObject first = courses.getJSONObject(0); //Or access in a loop using courses.length()
Debug.log("CourseID: "+ first.getString("courseId"));
You can do this:
JSONObject json = (JSONObject) JSONSerializer.toJSON(jsonTxt);
System.out.println(pilot.getString("aKey"));
Here you have an ArrayList yourObject
for (int i = 0; i < yourObject.size(); i++) {
System.out.println(yourObject.get(i).getCourseId());
System.out.println(yourObject.get(i).getStrDate());
}