How do I remove empty json nodes in Java with Jackson?

Question

I\'m a beginning java programmer, so I\'m sorry if my question is kind of dumb.

I have a JSON object that looks like this:

{
\"element1\" : {
    \"g         


        

Answer 1

Check this

How to not send an empty collection in jackson

For empty node in Json you can use

http://jackson.codehaus.org/1.1.2/javadoc/org/codehaus/jackson/node/ObjectNode.html#remove(java.lang.String)

Removing JSON elements with jackson

These can solve your problem.

Answer 2

I haven't tested it, but you probably want something like this:

public static void stripEmpty(JsonNode node) {
    Iterator<JsonNode> it = node.iterator();
    while (it.hasNext()) {
        JsonNode child = it.next();
        if (child.isObject() && child.isEmpty(null))
            it.remove();
        else
            stripEmpty(child);
    }
}

Answer 3

I want only to show direction how to do that with Json:

JSONObject jsonObj = new JSONObject(_message);

    Map<String, JSONObject> map = jsonObj.getMap();

    Iterator<String> it = map.keySet().iterator();

    while(it.hasNext()){
          String key =   it.next();

          JSONObject o = map.get(key);

          if(o.length() == 0){
              it.remove();
          }
    }

When JSONObject loads {} its length is 0, therefore you can drop it.

As A side note, you can use this method in recursion like:

JSONObject jsonObj = new JSONObject(_message);

invoke(jsonObj);

...

private static void invoke(JSONObject jsonObj) {
    Map<String, JSONObject> map = jsonObj.getMap();

    Iterator<String> it = map.keySet().iterator();

    while(it.hasNext()){
        String key =   it.next();

        JSONObject o = map.get(key);

        if(o.length() == 0){
            it.remove();
        }
        else{
            invoke(o);
        }
    }
}

I didn't add any validation but for sure , you need to verify instance of jsonObj.getMap() ...