Java Streams：如何根据键值过滤 object

Question

I have a class as below which is mapped to the response of one of the api request. The response json is nothing but RootResponse[]

public class RootResponse {

    String header;
    String tailer;
    List<Map<Object, subRecords>> transactions;
    DcfSummary summary;


}

The json response which I received is mapped to the class as map<string, Object>

below is the sample json response, In the transactions which is ( List<Map<Object, subRecords>> transactions;) there is a key for example "789983333" which is dynamic. so what I want to achieve if I give the key then I want to get that object which is

"789983333": {
                "r_01": "record1",
                "r_02": "record2",
                "r_03": "record3",
                "r_04": "record4"
            }
        }

[{
        "header": "header1",
        "transactions": [{
            "789983333": {
                "r_01": "record1",
                "r_02": "record2",
                "r_03": "record3",
                "r_04": "record4"
            }
        }],
        "tailer": "tailer1",
        "summary": {
            "item1": "370840",
            "item2": "0",
            "item3": "0",
            "item4": "0",
            "item5": "0",
            "item6": "0",
            "totaltransactions": "00000000"
        }
    },
    {
        "header": "header1",
        "transactions": [{
            "789983333": {
                "r_01": "record1",
                "r_02": "record2",
                "r_03": "record3",
                "r_04": "record4"
            }
        }],
        "tailer": "tailer1",
        "summary": {
            "item1": "370840",
            "item2": "0",
            "item3": "0",
            "item4": "0",
            "item5": "0",
            "item6": "0",
            "totaltransactions": "00000000"
        }
    }
]

I was trying to use streams in java but no luck. The idea is once I get the object based on the reference key then I can get records and validate the response. tried various options not able to get it. Any help would be appreciated.

Answer 1

Found the solution

            for (Map.Entry<String, Object> entry : RootResponse.entrySet()){

                RootResponse[] ls = (RootResponse[]) entry.getValue();
                for(RootResponse a : ls){
                     List<Map<Object, SubRecords>> dcfrecord = (List<Map<Object, SubRecords>>) a.getTransactions();
                   Optional<SubRecords> subRecords = Optional.of((SubRecords) dcfrecord.stream().flatMap(key -> key.entrySet().stream().filter(k1 -> k1.getKey().equals(rrn))).map(value -> value.getValue()).findFirst().get());
                   SubRecords subrecord = SubRecords.get();
                    System.out.println(gen4record.getR_6220());
                    if(gen4record != null){
                        break;
                    }
                }
            }