Java unable to parse nested json object

Question

Below is some sample code:

import org.json.JSONObject;

String k = "{\"root1\":\"{\\\"key1\\\":\\\"val1\\\",\\\"key2\\\":1,\\\"key3\\\":null}\",\"root2\":\"OTHERS\",\"root3\":1}";
JSONObject obj = new JSONObject(str);
System.out.println(obj);

/* 
here I want to do something like:
JSONObject innerObj = (JSONObject) obj.get("root1");
String k1 = innerObj.get("key1");

Also, should work with nested inner objects, so for example, should be able to do:
String k4 = innerObj.get("key1.innerKey1");
*/

{"root1":"{\"key1\":\"val1\",\"key2\":1,\"key3\":null}","root2":"OTHERS","root3":1}

On doing JSONObject innerObj = (JSONObject) obj.get("root1"); - it gives:

Exception in thread "main" java.lang.ClassCastException: java.lang.String cannot be cast to org.json.JSONObject

I tried Gson, JSONParser - but still unable to do it ...

Note: Parsing of string 'k' works fine, as the obj is populated correctly and is printed out. It fails when I try to access objects within this obj: JSONObject innerObj = (JSONObject) obj.get("root1");

The root1 key maps to a string. That's what the \" quotes are doing inside your JSON. It looks like your JSON was put together wrong. — khelwood
– khelwood, Commented Nov 2, 2020 at 19:35
Your root1 property is not a JSON object; it is a string whose value is JSON, whose root value is a JSON object. Correct the assembly if at all possible; if not, you'll need to extract the string and run it through parsing a second time. — chrylis -cautiouslyoptimistic-
– chrylis -cautiouslyoptimistic-, Commented Nov 2, 2020 at 19:48
@chrylis -cautiouslyoptimistic- - hw to do that ? i am using import org.json.JSONObject; — pirate_shady
– pirate_shady, Commented Nov 2, 2020 at 21:54

SKumar · Accepted Answer · 2020-11-02 23:43:46Z

1

There is utility StringEscapeUtils class in apache commons text library for such translations. Applying it will remove those extra double quotes around root1 value.

Add this commons-text jar dependency to your project.

Usage -

String k = "{\"root1\":\"{\\\"key1\\\":\\\"val1\\\",\\\"key2\\\":1,\\\"key3\\\":null}\",\"root2\":\"OTHERS\",\"root3\":1}";

// add this line
String unescapedJsonString = StringEscapeUtils.unescapeJson(k);

 // pass new json string to Json library
JSONObject obj = new JSONObject(unescapedJsonString);

edited Nov 2, 2020 at 23:43

answered Nov 2, 2020 at 23:38

SKumar

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Comments

Shubham Pathak · Accepted Answer · 2020-11-02 20:04:16Z

0

Please check this-

public static void main(String[] args) {

    String k ="{\"root1\":{\"key1\":\"val1\",\"key2\":1,\"key3\":null},\"root2\":\"OTHERS\",\"root3\":1}";
    JSONObject obj = new JSONObject(k);
    System.out.println(obj);
     
    //here I want to do something like:
    JSONObject innerObj = (JSONObject) obj.get("root1");
    Object k1 =  innerObj.get("key1");
    System.out.println(k1);
    Object k2 =  innerObj.get("key2");
    System.out.println(k2);
    Object k3 =  innerObj.get("key3");
    System.out.println(k3);
    
    System.out.println(obj.get("root2"));
    System.out.println(obj.get("root3"));
}

Output -

{"root1":{"key1":"val1","key2":1,"key3":null},"root2":"OTHERS","root3":1}
val1
1
null
OTHERS
1

answered Nov 2, 2020 at 20:04

Shubham Pathak

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2 Comments

pirate_shady Over a year ago

not sure who down voted it ... i did similar thing in my actual code, but when i access inner element and then print it, it gives something like: ``` JSONObject innerObj = (JSONObject) obj.get("root1"); logger.debug("inner obj: " + innerObj.toString()); ``` inner obj: {"bytes":[123,34,101],"empty":false}

pirate_shady Over a year ago

and my problem is as stated by @chrylis -cautiouslyoptimistic- above : 'Your root1 property is not a JSON object; it is a string whose value is JSON, whose root value is a JSON object. Correct the assembly if at all possible; if not, you'll need to extract the string and run it through parsing a second time.' yes, so value of my root1 is a string with JSONObj - not a JSONObj

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