Java检查字符串只允许逗号作为特殊字符

Question

如何检查以确保字符串可以包含的唯一特殊字符是逗号？

testString = "123,34565,222"  //OK

testString =  "123,123.123." //Fail

Answer 1

基于@Simeon 正则表达式的完整工作示例。这会重用单个 Matcher 对象，如果需要频繁进行检查，建议使用该对象。

import  java.util.regex.Pattern;
import  java.util.regex.Matcher;
public class OnlyLettersDigitsCommas  {

   //"": Dummy search string, to reuse matcher
   private static final Matcher lettersCommasMtchr = Pattern.
      compile("^[a-zA-Z0-9,]+$").matcher("");

   public static final boolean isOnlyLettersDigitsCommas(String to_test)  {
      return  lettersCommasMtchr.reset(to_test).matches();
   }

   public static final void main(String[] ignored)  {
      System.out.println(isOnlyLettersDigitsCommas("123,34565,222"));
      System.out.println(isOnlyLettersDigitsCommas("123,123.123."));
   }
}

输出:

[C:\java_code\]java OnlyLettersDigitsCommas
true
false