java - Using string stream as split result in lambda

Question

I need to split line based on comma and add it to a Map simultaneously in one go. I know that I can collect the splitted stream to list and then iterate over list for same effect. But I need to know if that can be done.

Input : List<String> - (A, B) (A,C)

Output : Map<String, List<String>> - (A, (B,C))

Example Code : (Contains Error)

public void edgeListRepresentation(ArrayList<String> edges){
        Map<String, List<String>> edgeList = new HashMap<>();
        edges.forEach(connection -> {

            Stream.of(connection.split(","))
                    .map((arr) -> {
                        edgeList.computeIfAbsent(arr[0], val -> new ArrayList<String>()).add(arr[1]);
                    });
        });

    }

     public static void main(String[] args) throws IOException {
        EdgeList edgeList = new EdgeList();
        edgeList.edgeListRepresentation(new ArrayList<String>(){
            {
                add("A, B");
                add("A, C");
                add("A, E");
                add("B, C");
                add("C, E");
                add("C, D");
                add("D, E");
            }
        });
    }

标签： javalambdajava-8java-stream

Answer 1

如果您想以自己的方式使其简单，则无需使用流

edges.forEach(connection -> {
  String[] arr = connection.split(",");
  edgeList.computeIfAbsent(arr[0], val -> new ArrayList<String>()).add(arr[1].trim());
});