正则表达式没有给出预期的输出

Question

Code:

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

public class Regex {
public static void main(String[] args) {
    String data = ". Shyam and you. Lakshmi and you. Ram and you. Raju and you. ";
    Pattern pattern = Pattern.compile("\\.\\s(.*?and.*?)\\.\\s");
    Matcher matcher = pattern.matcher(data);
    while (matcher.find()) {
        System.out.println(matcher.group(1));
    }

}
}

Expected output:

Shyam and you
Lakshmi and you
Ram and you
Raju and you

But the output i got was:

Shyam and you
Ram and you

Please correct me.

Answer 1

You are not getting adjacent matches, because you are matching the ".\\\\s" of the next pattern in the previous pattern. So, they won't be matched again.

You should use look-arounds:

Pattern.compile("(?<=\\.\\s)(.*?and.*?)(?=\\.\\s)");

Look-arounds are 0-length assertion. They won't consume the characters, but just check whether a pattern is there or not, either forward, or backward.

---

References:

• Regular Expression info - Look Around

Answer 2

我不是regexpert，但看起来你的模式与两个匹配。当每个句子之间只有一个。