regex - 正規表現または複数回出現しない文字

Question

文字が文字列に複数回出現するのを避けようとしています。この場合、一連の数字の中で 1 回だけ出現するカンマが必要です。

正しい一致:

,111111
11111,1111
11111,

不適切な一致:

1111,,11111
11,111,111

Answer 1

これを試して

(?im)^[0-9]*,[0-9]*$

または、より正確には

(?im)^([0-9]*,[0-9]+|[0-9]+,[0-9]*)$

説明

<!--
(?im)^([0-9]*,[0-9]+|[0-9]+,[0-9]*)$

Match the remainder of the regex with the options: case insensitive (i); ^ and $ match at line breaks (m) «(?im)»
Assert position at the beginning of a line (at beginning of the string or after a line break character) «^»
Match the regular expression below and capture its match into backreference number 1 «([0-9]*,[0-9]+|[0-9]+,[0-9]*)»
   Match either the regular expression below (attempting the next alternative only if this one fails) «[0-9]*,[0-9]+»
      Match a single character in the range between “0” and “9” «[0-9]*»
         Between zero and unlimited times, as many times as possible, giving back as needed (greedy) «*»
      Match the character “,” literally «,»
      Match a single character in the range between “0” and “9” «[0-9]+»
         Between one and unlimited times, as many times as possible, giving back as needed (greedy) «+»
   Or match regular expression number 2 below (the entire group fails if this one fails to match) «[0-9]+,[0-9]*»
      Match a single character in the range between “0” and “9” «[0-9]+»
         Between one and unlimited times, as many times as possible, giving back as needed (greedy) «+»
      Match the character “,” literally «,»
      Match a single character in the range between “0” and “9” «[0-9]*»
         Between zero and unlimited times, as many times as possible, giving back as needed (greedy) «*»
Assert position at the end of a line (at the end of the string or before a line break character) «$»
-->

Answer 2

1111を正しいものとして含めたい場合は、次のようにします。

^[0-9]*,?[0-9]*$  

そうでない場合...使用：

^[0-9]*,[0-9]*$  

説明：

^ = start of string  
[0-9]* = zero numbers or multiple numbers  
,? = a comma zero or 1 time  
,(without the ? following) = a comma must be here 
$ = the end of string

式を確認するのに最適なサイト
http://regexpal.com/
（上部の「^ $一致」を確認し、各行の最後でEnterキーを押してください）

Answer 3

Java では、1 文字のみをチェックする必要があるため、次の方法を使用して (正規表現を使用せずに) 実行できます。

private static boolean checkValidity(String str, char charToCheck) {
    int count = 0;
    char[] chars = str.toCharArray();
    for (char ch : chars) {
        if (ch == ',' && ++count > 1) {
            return false;
        }
    }

    return true;
}

次のように使用します。

public static void main(String args[]) {
    System.out.println(checkValidity("111,111,111", ','));
    System.out.println(checkValidity("111,,111", ','));
    System.out.println(checkValidity("111,111", ','));
}

出力は次のようになります。

false
false
true

必要に応じて。