Understanding regex in Java: split(“\t”) vs split(“\\t”) – when do they both work, and when should they be used

When using "\t", the escape sequence \t is replaced by Java with the character U+0009. When using "\\t", the escape sequence \\ in \\t is replaced by Java with \, resulting in \t that is then interpreted by the regular expression parser as the character U+0009.

So both notations will be interpreted correctly. It’s just the question when it is replaced with the corresponding character.