Question 374363 in Json Question posted in
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How to reach an upper element in JSON with Java streams

How can I reach a value of element "itemid" which has login "peter" and status "SLEEP" using streams in Java? Already I have a Jackson library and POJO classes in my project.

[
  {
    "itemid": "bf47",
    "name": "test",
    "workers": [
      {
        "user": {
          "id": "7074",
          "login": "john",
                },
        "status": [
          {
            "name": "WORK"
          }
        ]
      },
      
      {
        "user": {
          "id": "1237",
          "login": "peter",
                  },
        "status": [
          {
            "name": "WORK"
          },
          {
            "name": "SLEEP"
          }
        ]
      }
    ],
 
  },
  {
    "itemid": "ea277",
    "name": "test",
    "workers": [
      {
        "user": {
          "id": "2ce0",
          "login": "robert"
                 },
        "status": [
          {
            "name": "WORK"
          }
        ]
      }
    ],
  
  }
  
]

I tried in the following manner, but it didn’t work:

String id =  Arrays.stream(allItemId).flatMap(x->x.getworkers().stream())
                .filter(x->x.getUser().getLogin().equals(peter))
                .flatMap(x->x.getStatus().stream())
                .filter(x->x.getName().equals("SLEEP")).map(x->x.getItemId).findFirst().get();
Tags:

2

Answers


  1. 0 
    String id = allItemId.stream()
    .filter(item -> item.getWorkers().stream()
            .anyMatch(worker ->
                    "peter".equals(worker.getUser().getLogin()) &&
                    worker.getStatus().stream().anyMatch(status -> "SLEEP".equals(status.getName()))
            )
    )
    .findAny()
    .map(Item::getItemid)
    .orElse(null);
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  2. 0

    Flattening the stream will replace each Item with their Worker instances. Like so, you won’t be able anymore to retrieve the itemid you need.

    In your case, you might want to consult the nested structures with the intermediate operation filter and keep only the Item instances whose User‘s login matches peter and whose statuses contains SLEEP.

    Item res = Arrays.stream(allItemId).
                filter(item -> item.getWorkers().stream().anyMatch(worker -> worker.getUser().getLogin().equals("peter")
                        && worker.getStatus().stream().anyMatch(status -> status.getName().equals("SLEEP"))))
                .findAny().orElse(null);

    Here is also a live demo at OneCompiler printing the Item with id bf47

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