如何使用Java RegEx匹配输入的开头？

您可以使用元字符“\\A”来匹配输入的开头。

示例

import java.util.Scanner; import java.util.regex.Matcher; import java.util.regex.Pattern; public class Example { public static void main(String args[]) { //Reading String from user System.out.println("Enter a String"); Scanner sc = new Scanner(System.in); String input = sc.nextLine(); String regex = "\\A[0-9]"; //Compiling the regular expression Pattern pattern = Pattern.compile(regex); //Retrieving the matcher object Matcher matcher = pattern.matcher(input); int count = 0; if(matcher.find()) { System.out.println("Match found "); } else { System.out.println("Match not found "); } } }

输出1

Enter a String 12 sample text Match found

输出2

Enter a String sample text Match not found