在数组 Object 的情况下如何读取特定的 Map 键值

Question

I have the following Map structure

{empId=1234, empName=Mike, CDetails=[{"collegeName":"Peters Stanford","collegeLoc":"UK","collegeLoc":"UK"}]}

I need to read the value collegeLoc from the above Map

I tried this way, its working, but is there any better way

    myMap.entrySet().stream().filter(map -> map.getKey().equals("CDetails")).forEach(e -> {

            List<Object> objsList = (List<Object>) e.getValue();

            for(int i=0;i<objsList.size();i++)
            {
                HashMap<String,String> ltr = (HashMap<String, String>) objsList.get(i);

                System.out.println(ltr.get("collegeLoc"));
            }



        });

Answer 1

CDetails is a List , not a Map .

Try this:

empMap.entrySet().stream()
  .map(map -> map.get("CDetails"))
  .filter(Objects::nonNull)
  .flatMap(List::stream)
  .map(element -> ((Map)element).get("collegeLoc"))
  .filter(Objects::nonNull)
  .forEach(System.out::println);