How do you split a string of words and retain whitespaces?
Here is the code:
String words[] = s.split(" "); String s contains: hello world
After the code runs, words[] contains: "hello" "" world
Ideally, it should not be an empty string in the middle, but contain both whitespaces: words[] should be: "hello" " " " " world
How do I get it to have this result?
You could use lookahead/lookbehind assertions:
String[] words = "hello world".split("((?<=\\s+)|(?=\\s+))"); where (?<=\\s+) and (?=\\s+) are zero-width groups.
If you can tolerate both white spaces together in one string, you can do
String[] words = s.split("\\b"); Then words contains ("hello", " ", "world").
s.split("((?<= )|(?= ))"); is one way.
Technically, the regular expression is using lookahead and lookbehind. The single space after each = is the delimiter.
You could do something like this:
List<String> result = new LinkedList<>(); int rangeStart = 0; for (int i = 0; i < s.length(); ++i) { if (Character.isWhitespace(s.charAt(i))) { if (rangeStart < i) { result.add(s.substring(rangeStart, i)); } result.add(Character.toString(s.charAt(i))); rangeStart = i + 1; } } if (rangeStart < s.length()) { result.add(s.substring(rangeStart)); } Yeah, no regexes, sue me. This way you can see how it works more easily.
String.splitremoves the delimiter you provide to it (the space in this case). If you want a different behavior, you'd have to implement a variant ofsplityourself.