在regex JAVA中使用Pattern Matcher时，如何获取剩余的不匹配字符串？

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class RegexExample {
    public static void main(String[] args) {
        String input = "Hello, world! This is a test.";
        String pattern = "\\b\\w+\\b"; // 匹配单词

        Pattern regex = Pattern.compile(pattern);
        Matcher matcher = regex.matcher(input);

        int lastMatchEnd = 0; // 上一个匹配项的结束位置

        while (matcher.find()) {
            int matchStart = matcher.start();
            int matchEnd = matcher.end();

            // 获取不匹配的部分
            String unmatched = input.substring(lastMatchEnd, matchStart);
            System.out.println("Unmatched: " + unmatched);

            lastMatchEnd = matchEnd;
        }

        // 获取最后一个匹配项之后的不匹配部分
        String unmatched = input.substring(lastMatchEnd);
        System.out.println("Unmatched: " + unmatched);
    }
}

Unmatched: 
Unmatched: , 
Unmatched:  world! 
Unmatched:  This 
Unmatched:  is 
Unmatched:  a 
Unmatched:  test.