I am attempting to apply the map() function to a stream of strings right now such that the new stream contains a sorted version of each string. That is, instead of "cat" it will have "act". I am attempting to run the method as so:

Stream<String> sortedStream = validWordStream.map(s -> Arrays.sort(s.toString().toCharArray()));

However, it complains that the stream returned is a stream of Objects, not Strings:

Question

What intuitive changes do I have to make to the map() function such that I get a stream of sorted strings?

CodePudding user response：

since Array.sort's return type is void, you can not use its value as map result. Also, you won't have correct result if there are surrogate pairs.

So:

Stream<String> validWord = foo();
Stream<String> validSortedWord = validWord
    .map(s -> s.codePoints().sorted().toArray())
    .map(sortedCodepoints -> new String(sortedCodePoints, 0, sortedCodePoints.length))

(Edit: changed 3rd arguments of String constructor, see Sree Kumar's comment)

CodePudding user response：

Sort each char array and then generate a new String:

Stream<String> sortedStream = validWordStream
      .map(s -> { char[] c = s.toCharArray(); 
                  Arrays.sort(c);
                  return new String(c);});