Remove few elements from a Map of String to List for a specific key

RoyalTiger :

I have a Map. The input is coming from another class, so I can't change the format. The value is a List in my case. I want to remove a few elements for a particular key. For example, below is the input map:

Map<String, Object> map = new HashMap<>();
    map.put("1", Arrays.asList("A","V","C","M"));
    map.put("Roll", 123); 

This "map" has been given to me and I want to remove two entries for Key = "1", i.e., Arrays.asList("V","M")

I tried the below code and it worked. I want to know is there any better approach than this. Note: I am trying to do it using Java 8.

List<String> list = Arrays.asList("V","M") 
List<String> lst =  map.entrySet().stream()
            .map(Map.Entry::getValue)
            .filter(c -> c instanceof Collection)
            .map(c -> (Collection<String>)c)
            .flatMap(Collection::stream)
            .collect(Collectors.toList());

        lst.removeIf(c -> list.contains(c));

/** * After that, I can add this final list to the map again.. */

final output: <"1", {"A", "C"}>
                 <"Roll", 123>

Deadpool :

There is no need of stream for doing this, i prefer using computeIfPresent if key present in Map alter the value else ignore. Don't use Arrays.asList unless you need immutable list because it will not support remove operation

List<String> list = new ArrayList<String>();
    list.add("A");
    list.add("V");
    list.add("C");
    list.add("M");

    Map<String, Object> map = new HashMap<>();
    map.put("1", list);
    map.put("Roll", 123); 

    List<String> remove = Arrays.asList("V","M");

    map.computeIfPresent("1", (k,v)->{
              if(Objects.nonNull(v) && v instanceof List) {
                  @SuppressWarnings("unchecked")
                  List<String> result = (List<String>) v;
                  result.removeIf(i->remove.contains(i));
                  return  result;
              }
            return v;
    });

    System.out.println(map);    //{1=[A, C], Roll=123}