How to split a string with a space and leave anything inside a quotation alone?

Question

Given a string entered by a user, I'm trying to split the string by removing any whitespace and getting each token.

But I'm having difficulties for when I have a token in quotation marks. Here are some examples to better clarify:

User input: that is cool

Expected Output:

that
is
cool

User input: The book "Harry Potter" is cool

Expected Output:

The
book
"Harry Potter"
is
cool

User input: Here " is one final " example

Expected Output:

Here
"     is   one   final   "
example

This is what I have so far:

public static void main(String[] args) {
    String input;
    Scanner in = new Scanner(System.in);
    System.out.print("User input: ");
    input = in.nextLine();
    input = input.trim();
    input = input.replaceAll("\\s+", " ");
    String[] a = input.split(" ");

    for (String c: a) {
        System.out.println(c);
    }
}

It only works for the first example but for the examples with quotations, it splits the spaces inside the quoted tokens swell. Example 3 output:

Here
"
is
one
final
"
example

Answer 1

Don't focus on things you want to split on. It is easier to focus on things you want to find as result:

private static final Pattern p = Pattern.compile("\"[^\"]+\"|\\S+");
//                                     quotes---  ^^^^^^^^^^ 
//                                     non+whitespace        ^^^^ 
public static List<String> splitTokensAndQuotes(String text) {
    List<String> result = new ArrayList<>();
    Matcher m = p.matcher(text);
    while (m.find()) {
        result.add(m.group());
    }
    return result;
} 

Demo:

public static void main(String[] args) {

    splitTokensAndQuotes("that         is      cool")
            .forEach(System.out::println);
    System.out.println("------");

    splitTokensAndQuotes("the       book   \"Harry Potter\"   is   cool")
            .forEach(System.out::println);
    System.out.println("------");

    splitTokensAndQuotes("Here  \"     is   one   final   \"    example")
            .forEach(System.out::println);
    System.out.println("------");

}

Result:

that
is
cool
------
the
book
"Harry Potter"
is
cool
------
Here
"     is   one   final   "
example
------