How to parse simple JSON i JAVA

Question

I have the following valid JSON (I tested on jsonlint.com):

{
"Structure": {
    "paper": "Paper",
    "solid_reviewer": "Solid Reviewer",
    "second_reviewer": "2. Reviewer",
    "third_reviewer": "3. Reviewer"
},
"ReviewerGroup": {
    "3457": {
        "paper": "3457",
        "solid_reviewer": {
            "druidkey": "168",
            "match": "Interest match"
        },
        "second_reviewer": {
            "druidkey": "192",
            "match": "Interest match"
        },
        "third_reviewer": {
            "druidkey": "155",
            "match": "Interest match"
        }
    },
    "3458": {
        "paper": "3458",
        "solid_reviewer": {
            "druidkey": "229",
            "match": "Interest match"
        },
        "second_reviewer": {
            "druidkey": "145",
            "match": "Interest match"
        },
        "third_reviewer": {
            "druidkey": "123",
            "match": "Interest match"
        }
    },
    "275": {
        "paper": "275",
        "solid_reviewer": {
            "druidkey": "999",
            "match": "Interest match"
        },
        "second_reviewer": {
            "druidkey": "412",
            "match": "Interest match"
        },
        "third_reviewer": {
            "druidkey": "713",
            "match": "Interest match"
        }
    }
},
"failedPapers": {}
 }

In PHP, to decode this i simply do:

$response = json_decode($response);

and i can iterate through the $response object:

foreach ($response->ReviewerGroup as $r){
  $paperRev1 = $paperReviewDAO->find(**$r->paper**, 1);
  $revConf = $revConfDAO->findRevConfFromReviewer($confId,              
     **$r->solid_reviewer->druidkey**);
.
.
}

But it seems to be a lot more complicated in Java.

I have seen a lot of examples on how to read one object or an array of objects.

But how do i get all 'ReviewerGroup' (RG) objects and iterate through them? I need to extract the information from each of them and insert the data into a database (i know how to do that...) as an entity for each RG object.

I don't care what JSON library to use. I've looked into GSON and Jackson.

Thanks for any advice and ideas...

/ Kim

Answer 1

In Java (with Gson) it's as simple as that:

Map<String, Object> result = new Gson().fromJson(response, Map.class);

You can provide your own class as the second argument and in such case it will be deserialized into the new instance of that class.