Pablo Fernández Pablo Fernández - 4 months ago 57
JSON Question

Retrieving nested arrays values with JSON Java

I'm struggling to retrieve some values from a JSON file formatted like this one:

{
"search": {
"entry": [
{
"found": "identity=9454532,l=big,ton=grand,k=molvi",
"attribute": [
{
"name": "firstname",
"value": [
"Lucas"
]
},
{
"name": "lastname",
"value": [
"Brandon"
]
}
]
}
],
"return": {
"code": 0,
"message": "Success",
"count": 1
}
}
}


I have tried different approaches (json, gson, jayway-JsonPath) but I don't manage to get the values from the "attribute" array, only those from the first array. I don't know how to specify that "attribute" is an JSONArray and not a JSONObject or how to set the proper path to it.
This is the last code I was playing with which stops when it founds an array:

public void String nameObtain (String email) throws IOException{

String link = "http://jsonfile/" + email;

JSONObject json = readJsonFromUrl(link);
JSONObject rootObject = json.getJSONObject("search");
JSONArray firstArray = rootObject.getJSONArray("entry");

for (int i = 0, size = firstArray.length(); i < size; i++) {
JSONObject objectInArray = firstArray.getJSONObject(i);

String[] elementNames = JSONObject.getNames(objectInArray);
System.out.printf("%d ELEMENTS IN CURRENT OBJECT:\n", elementNames.length);
for (String elementName : elementNames) {
String value = objectInArray.getString(elementName);
System.out.printf("name=%s, value=%s\n", elementName, value);
}

}

}


What I would like to do is to get the values Lucas or Brandon. Any help will be much appreciated!

Answer

Libraries used:

import org.json.simple.JSONArray;
import org.json.simple.JSONObject;

Check the below code and step wise parsing

    JSONObject search = (JSONObject) jsonObject.get("search");//1
    JSONArray entry = (JSONArray) search.get("entry");//2
    for (int i = 0; i < entry.size(); i++) {
        JSONObject jsonObject1 = (JSONObject) entry.get(i);//3
        JSONArray jsonarray1 = (JSONArray) jsonObject1.get("attribute");//4
        for (int j = 0; j < jsonarray1.size(); j++) {
            System.out.println(((JSONObject) jsonarray1.get(j)).get(
                    "value").toString());//5

        }

    }

It will give the values mentioned step wise:

1) {"entry":[{"found":"identity=9454532,l=big,ton=grand,k=molvi","attribute":[{"name":"firstname","value":["Lucas"]},{"name":"lastname","value":["Brandon"]}]}],"return":{"code":0,"count":1,"message":"Success"}}

2) [{"found":"identity=9454532,l=big,ton=grand,k=molvi","attribute":[{"name":"firstname","value":["Lucas"]},{"name":"lastname","value":["Brandon"]}]}]

3) {"found":"identity=9454532,l=big,ton=grand,k=molvi","attribute":[{"name":"firstname","value":["Lucas"]},{"name":"lastname","value":["Brandon"]}]}

4) [{"name":"firstname","value":["Lucas"]},{"name":"lastname","value":["Brandon"]}]

5) ["Lucas"] and ["Brandon"]

So basically you have to take care of JSONObject and JSONArray respectively and do the parsing accordingly.

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