Question 265028 in Json Question posted in
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How to use Jackson JSON library to print everything in a json file, including nested array objects with no key and with objects in the array?

I need to print everything in a JSON file using Jackson in Java. I am 90% of the way there. Here is my Json File:

{
    "my-data": {
        "phone-number": "5555555555",
        "userId": "1234",
        "version": "2",
        "more-data": {
            "transaction-data": [
                {
                    "Merchant": "Walmart",
                    "authorized": "true",
                    "amount": "7.50",
                    "is_card_expired": false,
                    "credit_limit": "2000"
                }
            ]
        }
    }
}

I am able to print everything that has a key, but need help cleanly dealing with the array inside transaction-data. Notice that is an array with no key. Therefore, it is tricky to get inside, and my iterator (Iterator<Map.Entry<String, JsonNode>> Iterator = node.fields()) turns up empty. I cannot use node.elements(), because I need to get the key for everything, even if it is not something to print out. To print everything, my result should look something like

"phone-number": "5555555555"
"userId": "1234"
"version": "2"
"Merchant": "Walmart",
"authorized": "true",
"amount": "7.50",
"is_card_expired": false,
"credit_limit": "2000"

The best I have been able to come up with is after declaring my interator, I check if it hasNext(), and if not, then I create another iterator of elements (Iterator<JsonNode> iterator2 = node.elements();). While that has next I recursively call my method on each of the nodes inside that. This works, but I am not sure this is the best solution. How would you cleanly iterate through/traverse my JSON file to hit each and every node, regardless of if it is an object, an array, or a value node, and regardless of whether or not a key exists (if a key does not exist then I need not print it out, I just need to enter that container and print out the items inside of it

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2

Answers


  1. 0

    This can be solved using standard recursive approach.
    Where given entry is either a Object or Array of Objects.

    Following link has exact same problem statement as yours:

    java using JSONObject to loop recursive through any jsondata

    Hope this helps. Thanks.

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  2. 0

    You can quite easily do this with a JSON parser:

    JsonParser parser = new JsonFactory().createParser(json);
JsonToken token = parser.nextToken();
while (token != null) {
    switch (token) {
        case VALUE_FALSE:
        case VALUE_TRUE:
            System.out.printf(""%s": %b%n", parser.currentName(), parser.getBooleanValue());
            break;
        case VALUE_NULL:
            System.out.printf(""%s": null%n", parser.currentName());
            break;
        case VALUE_NUMBER_FLOAT:
        case VALUE_NUMBER_INT:
            System.out.printf(""%s": %d%n", parser.currentName(), parser.getNumberValue());
            break;
        case VALUE_STRING:
            System.out.printf(""%s": "%s"%n", parser.currentName(), parser.getText());
            break;
        default:
            // ignore
            break;
    }
    token = parser.nextToken();
}

    The parser has a method called currentValue() but that doesn’t work in the above example, it always returns null.

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