How to convert JsonArray to Hashmap

Question

I've been able to get a jsonarray from a json string, but don't know how to put it in a Hashmap with a String that shows the type of cargo and an Integer showing the amount.

The string:

"cargo":[   
    {"type":"Coals","amount":75309},        
    {"type":"Chemicals","amount":54454},        
    {"type":"Food","amount":31659},     
    {"type":"Oil","amount":18378}
]

possible this link can help http://stackoverflow.com/questions/4307118/jsonarray-to-hashmap — Shriram, Nov 08 '15 at 16:05
no sorry, already tried that one, some methods don't seem to work with that example — Zoef, Nov 08 '15 at 16:17
I tried the code from the link you gave me. But "JSONObject" and "optJSONObject" couldn't be resolved, maybe because I use javax.json libraries and that guy uses another library? — Zoef, Nov 10 '15 at 09:53

score 8 · Answer 1 · edited Jul 30 '17 at 22:54

8

This fixed it for me:

JsonArray jsoncargo = jsonObject.getJsonArray("cargo");

Map<String, Integer> cargo = new HashMap<>();
for (int i = 0; i < jsoncargo.size(); i++) {            
    String type = jsoncargo.getJsonObject(i).getString("type");
    Integer amount = jsoncargo.getJsonObject(i).getInt("amount");
    cargo.put(type, amount);
}

edited Jul 30 '17 at 22:54

Alex Karshin

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answered Nov 10 '15 at 10:12

Zoef

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Error @getJsonObject method – Ajay Takur Apr 17 '19 at 10:09
should be length() instead of size()? – DrAchernar Feb 24 '22 at 07:38

score 0 · Answer 2 · edited Mar 24 '22 at 10:02

I've been able to solve this using the Google GSON

    Map<String, Integer> cargoMap = new HashMap<>();

    JsonObject jsonObject = new Gson().fromJson(yourJsonString, JsonObject.class);
    JsonArray cargo = jsonObject.getAsJsonArray("cargo");
    cargo.forEach(item ->
    {
        String type = item.getAsJsonObject().get("type").getAsString();
        int amount = item.getAsJsonObject().get("amount").getAsInt();
        if (StringUtils.isNotBlank(type) || amount != 0) {
            cargoMap.put(type, amount);
        }
    });

Where "yourJsonString" is the whole json that contains the cargo json array.

score -1 · Answer 3 · edited Mar 12 '20 at 15:16

-1

Try creating a new HashMap, and loop through the JSONArray, adding each element to the hashmap.

JSONArray allCargo = jsonObject.getJsonArray("cargo");

HashMap<String, String> hm = new HashMap();

for(Object cargo : allCargo) {
    LinkedHashMap lhm = (LinkedHashMap) cargo;
    hm.put((String)lhm.get("type"), (String)lhm.get("amount"));
}

edited Mar 12 '20 at 15:16

Ṃųỻịgǻňạcểơửṩ

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answered Mar 12 '20 at 10:08

Satya

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1

While this code may solve the question, [including an explanation](https://meta.stackexchange.com/q/114762) of how and why this solves the problem would really help to improve the quality of your post, and probably result in more up-votes. Remember that you are answering the question for readers in the future, not just the person asking now. Please edit your answer to add explanations and give an indication of what limitations and assumptions apply. – David Buck Mar 12 '20 at 10:46

How to convert JsonArray to Hashmap

3 Answers3