Java如何使用所有格量词正则表达式？
所有格量词总是吃掉整个输入字符串，尝试一次（也只有一次）进行匹配。与贪婪的量词不同，所有格量词从不退缩，即使这样做会使整体匹配成功。
package org.nhooo.example.regex;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class PossessiveQuantifierDemo {
public static void main(String[] args) {
String[] regexs = {
"x?+",
"x*+",
"x++",
"x{2}+",
"x{2,}+",
"x{2,5}+"
};
String input = "xxxxxxx";
for (String r : regexs) {
Pattern pattern = Pattern.compile(r);
Matcher matcher = pattern.matcher(input);
//查找每个匹配并打印
System.out.format("Regex: %s%n", r);
while (matcher.find()) {
System.out.format("Text \"%s\" found at %d to %d.%n",
matcher.group(), matcher.start(),
matcher.end());
}
System.out.println("------------------------------");
}
}
}上面的代码片段的输出是：
Regex: x?+
Text "x" found at 0 to 1.
Text "x" found at 1 to 2.
Text "x" found at 2 to 3.
Text "x" found at 3 to 4.
Text "x" found at 4 to 5.
Text "x" found at 5 to 6.
Text "x" found at 6 to 7.
Text "" found at 7 to 7.
------------------------------
Regex: x*+
Text "xxxxxxx" found at 0 to 7.
Text "" found at 7 to 7.
------------------------------
Regex: x++
Text "xxxxxxx" found at 0 to 7.
------------------------------
Regex: x{2}+
Text "xx" found at 0 to 2.
Text "xx" found at 2 to 4.
Text "xx" found at 4 to 6.
------------------------------
Regex: x{2,}+
Text "xxxxxxx" found at 0 to 7.
------------------------------
Regex: x{2,5}+
Text "xxxxx" found at 0 to 5.
Text "xx" found at 5 to 7.
------------------------------