可能量词[X?+]匹配一次存在的X或根本不存在的X。
package com.tutorialspoint; import java.util.regex.Matcher; import java.util.regex.Pattern; public class PossesiveQuantifierDemo { private static final String REGEX = "T?+"; private static final String INPUT = "abcdTatW"; public static void main(String[] args) { // create a pattern Pattern pattern = Pattern.compile(REGEX); // get a matcher object Matcher matcher = pattern.matcher(INPUT); while(matcher.find()) { //Prints the start index of the match. System.out.println("Match String start(): "+matcher.start()); } } }
输出结果
Match String start(): 0 Match String start(): 1 Match String start(): 2 Match String start(): 3 Match String start(): 4 Match String start(): 5 Match String start(): 6 Match String start(): 7 Match String start(): 8