Regular expressions based on JAVA

Add ^$ The entire string meets the requirements

You can pass without adding part of the string to meet the requirements

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: Escape character

d: Any number                                                 (digit: number)

w : Any word character (number, letter, underline) (word: word)

s: Any blank character (t r n f x0B) (space: empty)

D: Any non-numeric character

W: Any non-numeric character Word character

S: any non-blank character

. Any character

\. Represents ordinary.

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"+": appears more than 1 time in a row------ --"^d+$"

"*": Indicates that the content appears 0-several times----"^d*$"

"?": ​​Indicates that the content appears 0-1 times------- "^d?$"

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[]

---------[ab]a and b can pass

---------[ a-z] means the range a, b, c...z can be used (the latter is larger than the front)

---------[a-bd-e] Multiple ranges

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{}

{n} appears n times---------------"^[a]{n}$"--------- -(n a can pass)

{n,} at least n times---------------"^[a]{n,}$"------- --(At least n a can pass)

{n,m} can appear n-m times----"^[a]{n,m}$"-------(n-m a can Pass)

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()--------The brackets are considered as a whole

|---------(123|321)---- ----123 or 321

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String emailRegEx = "^\d+$";

String email = "123";

System.out.println(email.matches(emailRegEx ));//true