How to modify an existing jsonobject in Java

Question

I have an existing jsonobject from the javax.json.JsonObject class.

I can't for the life of me figure out how I can modify the existing values in it. Ideally I'd like to do something like this:

if(object.getString("ObjectUUID").length()==0){
    object.put("ObjectUUID", UUID.randomUUID().toString());
}

According to the API you aren't allowed to modify that map.

http://docs.oracle.com/javaee/7/api/javax/json/JsonObject.html

This map object provides read-only access to the JSON object data, and attempts to modify the map, whether direct or via its collection views, result in an UnsupportedOperationException.

Currently I'm getting around the problem with a quick hack but there must be a better solution than this:

if(object.getString("ObjectUUID").length()==0){
    JsonObjectBuilder job = Json.createObjectBuilder();
    job.add("ObjectUUID", UUID.randomUUID().toString());
    for(String key : object.keySet()){
        if(!key.equals("ObjectUUID")){
            job.add(key, object.get(key));
        }
    }
    object = job.build();
}

So the question how do you modify an existing jsonobject?

Did you find any solution for this?

Jin Kwon
– Jin Kwon

2016-08-04 08:57:57 +00:00
Commented Aug 4, 2016 at 8:57 — Jin Kwon
– Jin Kwon, Commented Aug 4, 2016 at 8:57

Ryan J. McDonough · Accepted Answer · 2020-01-07 15:44:31Z

4

Without knowing the structure of the JSON object, it's a bit difficult to provide an answer that addresses your specific problem. The JsonObject instance is immutable, so you can't update it like Jackson's ObjectNode. As you've probably found, the JsonObject.add() method is basically useless, and depending on the implementation, may yield an UnsupportedOperationException. It's puzzling why it exists in the first place.

The way to modify the object is to create a JsonObjectBuilder instance that wraps the original JsonObject. If the object instance was your original JsonObject you'd probably want to do something like this:

if(object.getString("ObjectUUID").length()==0){
    object job = Json.createObjectBuilder(object)
                     .add("ObjectUUID", UUID.randomUUID().toString())
                     .build();
}

This took me a while to understand myself, and it gets a but more verbose if you have nested objects, etc.. If you're updating or replacing an object or array, you don't need to explicitly remove it before adding. There's pros and cons of the approach, but it beats the monthly ceremony of updating Jackson on a monthly basis :)

answered Jan 7, 2020 at 15:44

Ryan J. McDonough

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1 Comment

leonidos79 Over a year ago

This should be the accepted answer. And yes, whoever decided to make JsonObject and JsonArray immutable (and rely on Builder pattern) in Jakarta EE JSON spec clearly did not think about such use cases... which is a pity.

Amit Portnoy · Accepted Answer · 2014-08-20 11:04:44Z

1

I think there is no other way to modify a javax.json.JsonObject.

You should consider using jackson-databind.

answered Aug 20, 2014 at 11:04

Amit Portnoy

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Comments

hurricane · Accepted Answer · 2014-08-20 10:55:57Z

0

GSON Guide;

obj.addProperty("Id", "001");

System.out.println("Before: " + obj.get("Id")); // 001

obj.addProperty("Id", "002");

System.out.println("After: " + obj.get("Id")); // 002

edited Aug 20, 2014 at 10:55

answered Aug 20, 2014 at 10:32

hurricane

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4 Comments

Azrael Spare Over a year ago

JsonObject doesn't have an addProperty method and you can't interact with the map directly using put, you will get an UnsupportedOperationException.

Azrael Spare Over a year ago

Thanks for the suggestion, doesn't directly answer the question but gson is a nice alternative. I'll try it out.

hurricane Over a year ago

If you say i can explain with more. Good Luck.

Ryan J. McDonough Over a year ago

This solution is for GSON, not JSON-P, which is where the javax.json.JsonObject class comes from. I'm surprised this was the accepted answer.

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