Invalid escape sequence (valid ones are \ B \ t \ n \ f \ r \"\'\\)

This error occurs when I write a regular expression today: Invalid escape sequence (valid ones are \ B \ t \ n \ f \ r \"\'\\)

Solution: Change \ To \, and then OK.

This is a regular expression error. I searched the JDK help document and found the following paragraph:

According to the requirements of Java language specification, the backslash in the string of Java source code

It is interpreted as Unicode escape or other character escape. Therefore, two backlash lines must be used in the string literal value,

This indicates that the regular expression is protected and is not interpreted by the Java bytecode compiler. For example, when interpreted as a regular expression

The first parameter (obviously string. replaceall ("", "") is interpreted as a regular expression.

The nominal value "\ B" matches a single unsigned character, while "\ B"
Match the word boundary.