How to format a number with regular expression [duplicate]

问题

This question already has answers here:

How do I format a number in Java? (9 answers)

Closed 3 years ago.

I'm having a problem involving formatting a number. Here in Brazil we got a type of document called "CPF", which is a type of personal ID every citizen have.

So here is an example of a correctly formatted CPF number: 096.156.487-09

I'm trying to use a regular expression to format a string containing a CPF number, but I'm having a hard time at it. My current code is returning the unformatted numbers.

For instance: It should output 123.456.789-0 but instead I'm getting 1234567890.

This is my current code:

    String cpf ="09551130401";
    cpf = cpf.replaceAll("(\\d{2})(\\d{3})(\\d{3})(\\d{4})(\\d{2})", "$1.$2.$3-$4");
    System.out.println(cpf);

回答1:

I'm not sure I get your right .. But maybe you're looking for this pattern:

"(\\d{3})(\\d{3})(\\d{3})(\\d{2})"

And replace with $1.$2.$3-$4.

Online Demo

---

Full Code:

String cpf ="09551130401";
cpf = cpf.replaceAll("(\\d{3})(\\d{3})(\\d{3})(\\d{2})", "$1.$2.$3-$4");
System.out.println(cpf);
//=> 095.511.304-01

来源：https://stackoverflow.com/questions/37681277/how-to-format-a-number-with-regular-expression