Question 109706 in Json Question posted in
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Is there a way to filter an array and collect multiple JSON nodes into a Java list?

I have this JSON API response list:

[
    {
        "id": "demoType",
        "label": "Demo Type",
        "option": [
            "MAJOR"
        ]
    },
    {
        "id": "test",
        "label": "test",
        "option": [
            {
                "name": "testOne",
                "id": "1111",
                "demolId": "demoid-1"
            },
            {
                "name": "testTwo",
                "id": "2222",
                "demoId": "demoid-3"
            },
            {
                "name": "testThree",
                "id": "3333",
                "demolId": "demo-2"
            }
        ]
    },
    {
        "id": "sampleType",
        "label": "sample",
        "option": [
            {
                "name": "sampleA",
                "id": "4444"
            }
        ]
    },
    {
        "id": "runType",
        "label": "run one",
        "option": [
            {
                "name": "runA",
                "id": "eaf7d6a5-2038-45a0-9f06-6410694e5354",
                "demoId": "demolid-1"
            }
        ]
    },
    {
        "id": "city",
        "label": "City",
        "option": [
            "york",
            "tampa"
        ]
    }

]

I have a corresponding responseDTO:

@Data
@AllArgsConstructor
@NoArgsConstructor
public class DemoResponse {
  public String id;
  public String label;
  public ArrayList<Object> option;
}

The API response has got a property called option, which appears multiple times in a nested list. What I want to achieve is to collect the values of all the options properties to a list.

I tried like this:

DemoResponse[] response = (BaseClient.getResponse().as(DemoResponse[].class));
List<String> optionlList  =
            response.stream().map(newList -> newdList.toString()).collect(Collectors.toList());

stream could not be compiled. I am convinced that what I am doing is obviously wrong, but I am not sure how to achieve what I want which is to get all the values of the option fields in the API response and collect them into a list.

Tags:

2

Answers


  1. 0

    There is no .stream() over Array, you need to use Arrays.stream

    DemoResponse[] response = (BaseClient.getResponse().as(DemoResponse[].class));
List<String> optionlList  =
            Arrays.stream(response).map(res -> res.option.toString()).collect(Collectors.toList());
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  2. 0

    You can do like below, stream through the response array and flatMap the option and collect to a single list

            DemoResponse[] response = (BaseClient.getResponse().as(DemoResponse[].class));

        List<String> optionList = Arrays.stream(response)
                .flatMap(demoResponse -> demoResponse.getOption().stream())
                .map(Object::toString)
                .collect(Collectors.toList());

    Your optionList would be

    [MAJOR, {name=testOne, id=1111, demolId=demoid-1}, {name=testTwo, id=2222, demoId=demoid-3}, {name=testThree, id=3333, demolId=demo-2}, {name=sampleA, id=4444}, {name=runA, id=eaf7d6a5-2038-45a0-9f06-6410694e5354, demoId=demolid-1}, york, tampa]
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