将嵌套循环转换为流 Java 8

Question

I am trying to convert the below nested loop in to streams Java 8.

Each element in newself2 is a list of string - ["1 2","3 4"] needs to change to ["1","2","3","4"].

for (List<String> list : newself2) {
    // cartesian = [["1 2","3 4"],["4 5","6 8"]...] list = ["1 2","3 4"]...
    List<String> clearner = new ArrayList<String>();
    for (String string : list) { //string = "1 3 4 5"
        for (String stringElement : string.split(" ")) {
            clearner.add(stringElement);
        }
    }
    newself.add(clearner);
    //[["1","2","3","4"],["4","5","6","8"]...]
}

What I have tried till now -

newself2.streams().forEach(list -> list.foreach(y -> y.split(" ")))  

Now I am now sure how to add the split array in the inner for loop to a new list for x ?

Any help is greatly appreciated.

Answer 1

Here's how I'd do it:

List<List<String>> result = newself2.stream()
    .map(list -> list.stream()
            .flatMap(string -> Arrays.stream(string.split(" ")))
            .collect(Collectors.toList()))
    .collect(Collectors.toList());

Answer 2

This is other solution.

Function<List<String>,List<String>> function = list->Arrays.asList(list.stream()
            .reduce("",(s, s2) -> s.concat(s2.replace(" ",",")+",")).split(","));

and use this function

 List<List<String>> finalResult = lists
                                 .stream()
                                 .map(function::apply)
                                 .collect(Collectors.toList());

---

with for loop is similar to this:

  List<List<String>> finalResult = new ArrayList<>();
    for (List<String> list : lists) {
        String acc = "";
        for (String s : list) {
            acc = acc.concat(s.replace(" ", ",") + ",");
        }
        finalResult.add(Arrays.asList(acc.split(",")));
    }