正则表达式模式，不允许在两者之间使用逗号分隔

Question

任何人都可以在这里帮忙！ 我需要一个正则表达式，在其中我只能在几个Enum值中使用逗号。 例如：

 Savings Account,Current Account,Credit card --> valid
 Savings Account --> valid
Savings Account,Credit Card --> valid
Credit Card,Savings Account --> valid
(Space or any special character)Savings Account --> Invalid
Savings Account(space or any special character) --> Invalid
Savings AccountCurrent Account --> Invalid (it should be separated by comma)

我已经尝试过以下表达式，但它甚至也接受Savings AccountCurrent Account。

((Savings Account|Current Account|Credit Card)[,]?)+\b

Answer 1

您在这里：

^(Savings Account|Current Account|Credit Card)(([,](Savings Account|Current Account|Credit Card))*)$

解释：

^(Savings Account|Current Account|Credit Card)  # Starts with one of the Enums defined
(([,](Savings Account|Current Account|Credit Card))*)$  # Optionally contains any numbers of defined enums prefixed by `,` and ends

如果不想让相同的字符串出现两次：

^(Savings Account|Current Account|Credit Card)(,(?!\1)(Savings Account|Current Account|Credit Card))?(,(?!\3)(?!\1)(Savings Account|Current Account|Credit Card))?$

解释：

^(Savings Account|Current Account|Credit Card)  # Capture group 1, matches one of the defined enums
(,  # start of capture group 2, checks for comma
    (?!\1)  # Negative Lookahead, makes sure it doesn't matches the result of group 1
    (Savings Account|Current Account|Credit Card)  # Capture group 3, matches one of the defined enums
)?  # end of capture group 2, make stuff inside it optional
(,  # start of capture group 4, checks for comma
    (?!\3)  # Negative Lookahead, makes sure it doesn't matches the result of group 3
    (?!\1)  # Negative Lookahead, makes sure it doesn't matches the result of group 1
    (Savings Account|Current Account|Credit Card)  # Capture group 5, matches one of the defined enums
 )?$  # end of capture group 4, make stuff inside it optional