Java String conversion to JSON can not be done

Question

I have JSON which I get from server:

 "[{\"id\":\"1\",\"name\":\"Milos\",\"city\":\"Smederevo\",\"email\":\"milos\",\"password\":\"\"},
 {\"id\":\"3\",\"name\":\"Boban\",\"city\":\"Beograd\",\"email\":\"bole\",\"password\":\"\"},
 {\"id\":\"4\",\"name\":\"Pele\",\"city\":\"Brazil\",\"email\":\"pele@pele.com\",\"password\":\"\"},
 {\"id\":\"5\",\"name\":\"admin\",\"city\":\"Smederevo\",\"email\":\"admin\",\"password\":\"\"}]"

I am using that json and sending to my thread (android thread):

  try {
            // Method from which I am getting Json described above
            String s = dm.getAllUsers();

            /*JSONParser jp = new JSONParser();             
            JsonElement jelement = new JsonParser().parse(s);   
                JsonArray array1 = jelement.getAsJsonArray();*/

            JSONArray array = new JSONArray(s);
            for (int i = 0; i < array.length(); i++) {

                 JSONObject menuObject = array.getJSONObject(i);

                 // doing something with the object
            }
        } catch (JSONException e) {
            e.printStackTrace();
        }

I can not process that Json at all. I am getting the error "java.lang.String cannot be converted to JSONArray". A know that problem is caused by "\", and I just do not know how to get rid of "\".

I tried:

1) s.replace("\\", "");
2) s.replace("\"", "'");
3) s.replaceAll("\\", "");
4) s.replaceAll("\"", "'");

In order to erase "\" but replace do not react at all. I also tried to solve problem with "google-gson-2.2.2" library (code under the comment above, under the method).

Any advice, please?

i think you need to fix your server rather than doing extra work at client side — waqaslam, Mar 18 '13 at 10:26
I would do `s = s.replaceAll("\\\"", "\"");` (replace \" by ", while leaving potential other \ untouched) — njzk2, Mar 18 '13 at 10:29
My server side is simple: return jSearializer.Serialize(userList); It just return serialized json object from the "userList". — Milos, Mar 18 '13 at 11:08
.net restful WS, runs on IIS. userList is list of user object. — Milos, Mar 18 '13 at 12:36

Pramod J George · Answer 1 · 2013-03-18T10:57:13.413

5

Try this solution.

s.replaceAll("\\\\", "");

This will definitely work.

edited Mar 18 '13 at 10:57

answered Mar 18 '13 at 10:26

Pramod J George

1,723
12
24

score 4 · Accepted Answer · answered Mar 18 '13 at 12:17

Problem has been solved with:

 1) s = s.trim();
 2) s = s.substring(1, s.length()-1);
 3) s = s.replace("\\", "");

My json has been retrieved with "double quotes" on the beginning and on the end. I do not know how string variable can not figure out that "double quotes" is for "beginning" and for "ending" of string.

Thank you everybody for helping.

score 4 · Answer 3 · edited Apr 22 '15 at 09:31

It is working for me...

In your json the value of "Your Json" is inclused inside "" so it's considered a string not an array..

So the solution is one of two things:

If you can modify the server response, remove the "" from arround the json array. or parse it first as string and then create a json array from that string like..

String notes = jobj.getString("GetNotesResult");
jarray = new JSONArray(notes);

score 2 · Answer 4 · answered Mar 18 '13 at 11:07

I have no idea why its not working for you. Dot net web services do respond with \ but Java capable of parsing it. I did as below and it worked.

I've coded like this.

JSONArray users = null;
String jsStr =  "[{\"id\":\"1\",\"name\":\"Milos\",\"city\":\"Smederevo\",\"email\":\"milos\",\"password\":\"\"},{\"id\":\"3\",\"name\":\"Boban\",\"city\":\"Beograd\",\"email\":\"bole\",\"password\":\"\"},{\"id\":\"4\",\"name\":\"Pele\",\"city\":\"Brazil\",\"email\":\"pele@pele.com\",\"password\":\"\"}, {\"id\":\"5\",\"name\":\"admin\",\"city\":\"Smederevo\",\"email\":\"admin\",\"password\":\"\"}]";
try {
    users = new JSONArray(jsStr);
} catch (JSONException e) {
    e.printStackTrace();
}

Log.v("JSONStr", String.valueOf(users.length()));
for(int i = 0; i<users.length(); i++){
    try {
        Log.v("Name", users.getJSONObject(i).getString("name"));
    } catch (JSONException e) {
        e.printStackTrace();
    }
}

See the LogCat

03-18 16:34:46.459: V/JSONStr(307): 4
03-18 16:34:46.479: V/Name(307): Milos
03-18 16:34:46.479: V/Name(307): Boban
03-18 16:34:46.479: V/Name(307): Pele
03-18 16:34:46.479: V/Name(307): admin

It is very interesting. Your example working for me in the same method. But my json from the server can not be parsed, even he is looking the same as your string above (jsStr). maybe my json (my string) has some covered character which I can not see. — Milos, Mar 18 '13 at 11:36
Hmm very peculiar I've used many dot net services with the same logic. did you try and `trim` the string before parsing it? — Jay Mayu, Mar 18 '13 at 12:03

score 2 · Answer 5 · answered Mar 18 '13 at 11:44

Your json will be valid only if you remove the back slashes () in between. You could use something like: strJson = strJson.replaceAll("\\\\", ""); OR strJson = strJson.replace("\\", ""); to remove the slashes () in between your json String. Please note that replaceAll() method treats the first argument as a regex, so you must double escape the backslash but, the replace() method treats it as a literal string, so you only have to escape it once. Please have a look at the below example for better understanding: I have kept your json text in a file named json.txt in my hard-drive for demonstration. The contents in the file looks like this:

[{\"id\":\"1\",\"name\":\"Milos\",\"city\":\"Smederevo\",\"email\":\"milos\",\"password\":\"\"},
 {\"id\":\"3\",\"name\":\"Boban\",\"city\":\"Beograd\",\"email\":\"bole\",\"password\":\"\"},
 {\"id\":\"4\",\"name\":\"Pele\",\"city\":\"Brazil\",\"email\":\"pele@pele.com\",\"password\":\"\"},
 {\"id\":\"5\",\"name\":\"admin\",\"city\":\"Smederevo\",\"email\":\"admin\",\"password\":\"\"}]

Now the code for getting the json array:

package com.stackoverflow.com;

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;


public class JsonTest {

    public static void main(String[] args) {    

        try {
            FileReader fileReader = new FileReader("C:/Users/sarath_sivan/Desktop/json.txt");
            BufferedReader br = new BufferedReader(fileReader); 
            StringBuilder strJsonBuilder = new StringBuilder();
            String strLine; 

            while((strLine = br.readLine()) != null) { 
                strJsonBuilder.append(strLine);
            }

            String strJson = strJsonBuilder.toString();
            strJson = strJson.replaceAll("\\\\", ""); /*OR you can use strJson = strJson.replace("\\", "");*/
            JSONArray jsonArray = new JSONArray(strJson);

            for (int i = 0; i < jsonArray.length(); i++) {
                JSONObject menuObject = jsonArray.getJSONObject(i);
                System.out.println("id: " + menuObject.getInt("id"));
                System.out.println("name: " + menuObject.getString("name"));
                System.out.println("city: " + menuObject.getString("city"));
                System.out.println("email: " + menuObject.getString("email"));
                System.out.println("password: " + menuObject.getString("password"));
                System.out.println();
                // do something with your JSON
            }

            fileReader.close();

        } catch (JSONException e) {
            e.printStackTrace();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

    }

}

score 1 · Answer 6 · answered Mar 18 '13 at 10:27

1

s = s.replace("\\", "");
System.out.println(s);

You need to assign your modified String back to s. This gives a proper parsable JSON.

answered Mar 18 '13 at 10:27

Rahul

44,383
11
84
103

Yes, it is work, but even with that , my json can not be parsed to array. I did not know that I need to retrieve back my string back to "s", usual it works without retrieving. – Milos Mar 18 '13 at 11:39

score 0 · Answer 7 · edited May 23 '17 at 12:01

I don't really like the various String.replaceAll(rexex, "") solutions. What if some of the strings in your JSON contain a \ as part of the information rather than the formatting? I see a 'password' field in your JSON. I don't know whether this is going to be clear text or a hash, but in the case of the former, your program might break if a user uses a backslash in their password.

What you want to do here is unescape a string. This is a problem that as far as I can tell, can't be solved with a simple regex, but it is a problem that has been solved thousands of times before. No need to reinvent the wheel.

How to unescape a string literal in java

Java String conversion to JSON can not be done

7 Answers7

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