JSONObject.accumulate() with Map produces invalid JSON in toString()

[vrubal]

Bug: JSONObject.accumulate() with Map produces invalid JSON in toString()

Version

• Broken: 20250517, 20251224
• Works correctly: 20240303

Description

When using JSONObject.accumulate(String key, Map value) followed by toString(), the nested Map is serialized using Java's Map.toString() format ({key=value, key=value}) instead of valid JSON ({"key":"value","key":"value"}).

This is a regression from version 20240303 where accumulate() would properly wrap the Map into a JSONObject internally before storing it.

Steps for Reproduction

import org.json.JSONObject;
import java.util.HashMap;
import java.util.Map;

public class OrgJsonAccumulateBug {
    public static void main(String[] args) {
        Map<String, String> responseMap = new HashMap<>();
        responseMap.put("responseCode", "00");

        Map<String, String> data= new HashMap<>();
        data.put("firstName", "John");
        data.put("lastName", "Doe");

        JSONObject jsonOut = new JSONObject(responseMap);
        jsonOut.accumulate("data", data);

        System.out.println(jsonOut.toString());
    }
}

Expected Output (valid JSON)

{"responseCode":"00","data":{"firstName":"John","lastName":"Doe"}}

Actual Output (invalid — Java Map.toString())

{"responseCode":"00","data":"{firstName=John, lastName=Doe}"}

Impact

Any code that uses accumulate() to add a Map to a JSONObject and then uses toString() to produce JSON for downstream parsing (e.g., Jackson ObjectMapper deserialization) will fail because the output is not valid JSON.

Jackson throws:

com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot construct instance of `MyClass`:
no String-argument constructor/factory method to deserialize from String value ('{key=value, ...}')

Workaround

Use put() with explicit new JSONObject(map) wrapping:

jsonOut.put("data", new JSONObject(tokenData));

Suggested Fix

accumulate() should wrap Map values in new JSONObject(map) (and List values in new JSONArray(list)) before storing, as it did in 20240303.

[stleary]

@vrubal Thanks for raising an issue. When I attempt this code with releases 20240303, 20250517, 20251224, and 20260522, I get the same result:

    @Test
    public void foo() {
        Map<String, String> responseMap = new HashMap<>();
        responseMap.put("responseCode", "00");

        Map<String, String> data= new HashMap<>();
        data.put("firstName", "John");
        data.put("lastName", "Doe");

        JSONObject jsonOut = new JSONObject(responseMap);
        jsonOut.accumulate("data", data);

        System.out.println(jsonOut.toString());
    }

Output: {"data":{"firstName":"John","lastName":"Doe"},"responseCode":"00"}

Please check your recreate steps. The code seems to be working correctly.

[vrubal]

@stleary Thanks for the response, I did try with 20250517, 20251224 version where its broken. Seems to be working with 20260522.