parse recursively unknown json input structure in java

Question

I'm trying to parse recursively unknown json input structure in java like the format below and trying to rewrite the same structure in another json.

Meanwhile I need to validate each & every json key/values while parsing.

{"Verbs":[{
    "aaaa":"30d", "type":"ed", "rel":1.0, "id":"80", "spoken":"en", "ct":"on", "sps":null
},{
    "aaaa":"31", "type":"cc", "rel":3.0, "id":"10", "spoken":"en", "ct":"off", "sps":null
},{
    "aaaa":"81", "type":"nn", "rel":3.0, "id":"60", "spoken":"en", "ct":"on", "sps":null
}]}

Please advice which json parser I can use for reading and writing unknown json content.

How to parse each json element and reassemble it as same as input — erdarun
– erdarun, Commented Mar 1, 2014 at 8:09
I want to validate each & every json token key/value for special chars. Then I will replace the values and reframe json again back to old structure — erdarun
– erdarun, Commented Mar 1, 2014 at 9:08
(Don't use Jackson, or any other "we'll build your POJOs for you" tool, unless the structure is fairly regular and repeatable. Unless you really understand them they cause more confusion than they're worth.) — Hot Licks
– Hot Licks, Commented Mar 1, 2014 at 19:26

Leos Literak · Accepted Answer · 2014-03-01 09:13:21Z

4

This way you can recursively parse JSON object:

import com.eclipsesource.json.JsonArray;
import com.eclipsesource.json.JsonObject;
import com.eclipsesource.json.JsonValue;

public class JsonQuestion {

    public static void main(String[] args) {
        String input =  "{\"Verbs\":[{\n" +
                "    \"aaaa\":\"30d\", \"type\":\"ed\", \"rel\":1.0, \"id\":\"80\", \"spoken\":\"en\", \"ct\":\"on\", \"sps\":null\n" +
                "},{\n" +
                "    \"aaaa\":\"31\", \"type\":\"cc\", \"rel\":3.0, \"id\":\"10\", \"spoken\":\"en\", \"ct\":\"off\", \"sps\":null\n" +
                "},{\n" +
                "    \"aaaa\":\"81\", \"type\":\"nn\", \"rel\":3.0, \"id\":\"60\", \"spoken\":\"en\", \"ct\":\"on\", \"sps\":null\n" +
                "}]}";

        JsonObject jsonObject = JsonObject.readFrom(input);
        handleObject(jsonObject);
    }

    private static void handleValue(JsonObject.Member member, JsonValue value) {
        if (value.isArray()) {
            if (member != null) {
                System.out.print("name = " + member.getName());
            }
            System.out.println("array value ");
            recurseArray(value.asArray());
        } else if (value.isBoolean()) {
            if (member != null) {
                System.out.print("name = " + member.getName());
            }
            System.out.println(", boolean value = " + value.asBoolean());
        } else if (value.isNull()) {
            if (member != null) {
                System.out.print("name = " + member.getName());
            }
            System.out.println(", null value");
        } else if (value.isNumber()) {
            if (member != null) {
                System.out.print("name = " + member.getName());
            }
            System.out.println(", number value = " + value.asDouble());
        } else if (value.isObject()) {
            if (member != null) {
                System.out.print("name = " + member.getName());
            }
            System.out.println(", object value ");
            handleObject(value.asObject());
        } else if (value.isString()) {
            if (member != null) {
                System.out.print("name = " + member.getName());
            }
            System.out.println(", string value = " + value.asString());
        }
    }

    private static void handleObject(JsonObject object) {
        for (JsonObject.Member next : object) {
            JsonValue value = next.getValue();
            handleValue(next, value);
        }
    }

    private static void recurseArray(JsonArray array) {
        for (JsonValue value : array) {
            handleValue(null, value);
        }
    }
}

answered Mar 1, 2014 at 9:13

Leos Literak

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7 Comments

erdarun Over a year ago

Thanks for your reply, Parallely can we frame json response while parsing each & every values.

Leos Literak Over a year ago

Sorry I do not understand your comment, is it question?

erdarun Over a year ago

yes can we achieve the same parsing logic in gson/jackson library? Because we are using gson/jackson libs only in my project,

Leos Literak Over a year ago

I think so. But I use this one.

Leos Literak Over a year ago

It would be better if you specify COMPLETE requirements in advance before somebody spent some time trying to help you.

|

helvete · Accepted Answer · 2020-01-17 12:02:45Z

Using gson library https://sites.google.com/site/gson/gson-user-guide

public void parseJson() {
     String jsonStr = "";//input json String.
     JsonParser parser = new JsonParser();
     JsonElement jsonElement = parser.parse(jsonStr);
     processJsonElement(jsonElement);
}


private void processJsonElement(JsonElement e) {
    if (e.isJsonArray()) {
        processJsonArray(e.getAsJsonArray());
    } else if (e.isJsonNull()) {
        processJsonNull(e.getAsJsonNull());
    } else if (e.isJsonObject()) {
        processJsonObject(e.getAsJsonObject());
    } else if (e.isJsonPrimitive()) {
        processJsonPrimitive(e.getAsJsonPrimitive());
    }
}

private void processJsonArray(JsonArray a) {
    for (JsonElement e : a) {
        processJsonElement(e);
    }
}

private void processJsonNull(JsonNull n) {
    System.out.println("null || : " + n);
}

private void processJsonObject(JsonObject o) {
    Set<Map.Entry<String, JsonElement>> members= o.entrySet();
    for (Map.Entry<String, JsonElement> e : members) {
        System.out.println("Processing object member: " + e.getKey());
        processJsonElement(e.getValue());
    }
}

private void processJsonPrimitive(JsonPrimitive p) {
    System.out.println("Primitive || :" + p);
}

Or Jackson

public void processJson() {
    ObjectMapper objectMapper = new ObjectMapper();
    try {
        JsonNode node = objectMapper.readTree(jsonStr);
        System.out.println(node);
        processNode(node);
    } catch (IOException e) {
        throw new RuntimeException(e);
    }

}

private void processNode(JsonNode n) {
    if (n.isContainerNode()) {
        processJsonContainer(n.iterator());
    } else if (n.isNull()) {
        System.out.println("Null || :" + n);
    } else if (n.isNumber()) {
        System.out.println("Number || :" + n.asDouble());
    } else if (n.isBoolean()) {
        System.out.println("Boolean || :" + n.asBoolean());
    } else if (n.isTextual()) {
        System.out.println("Text || :" + n.asText());
    }
}

private void processJsonContainer(Iterator<JsonNode> iterator) {
   while (iterator.hasNext()) {
       processNode(iterator.next());
   }
}

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