Find total of a value from List<Obj> using Java8 streams

user_4217324 0
Viewed 46

Below is my json request. My requirement is to find total of the "cols"."value" field if "cols"."name"="tran_amt".

{
  "request" : {
    "reqID" : "6839796504132",
    "processID" : 97904250,
    "tables" : [ {
      "tableName" : "TABLE_NAME",
      "records" : [ {
        "recordID" : "record_id1",
        "cols" : [ {
          "name" : "tran_amt",
          "type" : "VARCHAR2",
          "value" : "562356"
        }, {
          "name" : "tran_id",
          "type" : "VARCHAR2",
          "value" : "123456"
        } ]
      }, {
        "recordID" : "record_id2",
        "cols" : [ {
          "name" : "tran_amt",
          "type" : "VARCHAR2",
          "value" : "987098"
        }, {
          "name" : "tran_id",
          "type" : "VARCHAR2",
          "value" : "123456"
        } ]
      } ]
    } ]
  }
}

Here is the solution I had tried,

cols = request.getTables().get(0).getRecords().get(0).getCols();
total = cols.stream().filter(o -> "tran_amt".equalsIgnoreCase(o.getName())).mapToInt(o -> Integer.valueOf(o.getValue())).sum();

My solution retrieves the "value" from the first obj of "cols" only (in this case 562356). It doesnt sum all "values" matching the criteria.

Any inputs on where I am wrong?

Thanks in advance.

java-stream java-8 collections stream java
2 Answers

If you want to sum up all values of value field in Col from all Records for first table at 0 index

total = getTables().get(0)
             .getRecords()
             .stream()
             .map(Col::getCols)
             .flatMap(List::stream)
             .filter(o -> "tran_amt".equalsIgnoreCase(o.getName()))
             .mapToInt(o -> Integer.valueOf(o.getValue())).sum();
user_99591520

Try this:

total = request.getTables()
               .stream()
               .flatMap(t -> t.getRecords().stream())
               .flatMap(r -> r.getCols().stream())
               .filter(c -> "tran_amt".equalsIgnoreCase(c.getName()))
               .mapToInt(c -> Integer.valueOf(c.getValue()))
               .sum();
user_105846050
Related