JAVA - json parser - keys() to parse unknown json format?

Question

I try to parse a simple json dictionary, so I read many tutorials and threads on how to achieve this

but there is no "keys()" nor "keySet()" defined for JSONObject nor JSONArray

I downloaded the library here :

http://www.java2s.com/Code/Jar/j/Downloadjsonsimple111jar.htm

I am starting to wonder if I use the right library

here is my code :

import org.json.simple.parser.ParseException;
import org.json.simple.parser.JSONParser;
import org.json.simple.JSONArray;
import org.json.simple.JSONObject;

JSONParser parser = new JSONParser();
JSONObject obj = (JSONObject)parser.parse(json.trim());
Iterator keys = obj.keys(); <<<<<<<<<<<<<<<<<<<<<<<<<<<< keys() undefined
while(keys.hasNext()) {
    String key = keys.next();
}

json example :

{a:132,b:"1321",test:"something"}

any help appreciated

thanks

I try to use org.json.JSONObject but I can't find it anywhere — phil123456, Nov 27 '18 at 09:31
honnestly, if anyone could help me parse json in java, I dont care which library, so far it's a complete mess — phil123456, Nov 27 '18 at 09:32
I think I found it http://www.java2s.com/Code/Jar/o/Downloadorgjsonjar.htm — phil123456, Nov 27 '18 at 09:44
Possible duplicate of [How to iterate over a JSONObject?](https://stackoverflow.com/questions/9151619/how-to-iterate-over-a-jsonobject) — NickAth, Nov 27 '18 at 09:46
Please don't post answers in your question: post it as an answer instead. — Mark Rotteveel, Nov 27 '18 at 19:36

score 0 · Accepted Answer · answered Nov 27 '18 at 09:29

0

You can try this:

JSONObject jsonArray = ...//get json object

Iterator<?> keys = jsonArray.keys();

while( keys.hasNext() ) {
    String key = (String) keys.next();
    System.out.println("Value: " + jsonArray.get(key));
    System.out.println("Key: " + key);
}

answered Nov 27 '18 at 09:29

Sai prateek

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as mentioned in my question there is no .keys() method – phil123456 Nov 27 '18 at 09:41
In json-simple,https://github.com/fangyidong/json-simple/blob/master/src/main/java/org/json/simple/JSONObject.java JSONObject extends HashMap, so you should use keySet()... or change to use the json.org library instead – Sai prateek Nov 27 '18 at 09:49
YES !!! it works using this library http://www.java2s.com/Code/Jar/o/Downloadorgjsonjar.htm – phil123456 Nov 27 '18 at 09:51
I had keySet undefined with simpleJSON – phil123456 Nov 27 '18 at 09:51

score 0 · Answer 2 · answered Nov 27 '18 at 09:51

I think keySet().iterator() is, what you need:

    JSONParser parser = new JSONParser();
    JSONObject obj = (JSONObject)parser.parse(json.trim());
    Iterator keys = obj.keySet().iterator();
    while(keys.hasNext()) {
        String key = (String)keys.next();
    }

score 0 · Answer 3 · answered Nov 27 '18 at 10:07

Check the following. You have a few problems I have outlined afterwards.

import org.json.simple.parser.ParseException;
import org.json.simple.parser.JSONParser;
import org.json.simple.JSONArray;
import org.json.simple.JSONObject;
import java.util.*;

public class JavaJson{
    public static void main(String ... args){
        try{
            String json = "{\"name\":\"TEST\"}"; //Or whatever
            JSONParser parser = new JSONParser();
            JSONObject obj = (JSONObject)parser.parse(json.trim());
            Iterator itr = obj.keySet().iterator();
            while(itr.hasNext()){
                System.out.println((String)itr.next());
            }
        }
        catch(ParseException ex){
            ex.printStackTrace();
        }
    }
}

Problems being,

It is Iterator itr = obj.keySet().iterator(); not Iterator keys = obj.keys();. JSONObject does not have a definition for keys().
Missing import import java.util.*. Iterator is available in there.
Should either catch or throw ParseException.

JAVA - json parser - keys() to parse unknown json format?

3 Answers3

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