replace \n and \r\n with <br /> in java

Question

This has been asked several times for several languages but I can't get it to work. I have a string like this

String str = "This is a string.\nThis is a long string.";

And I'm trying to replace the \n with <br /> using

str = str.replaceAll("(\r\n|\n)", "<br />");

but the \n is not getting replaced. I tried to use this RegEx Tool to verify and I see the same result. The input string does not have a match for "(\r\n|\n)". What am i doing wrong ?

Answer 1

That should work, but don't kill yourself trying to figure it out. Just use 2 passes.

str  = str.replaceAll("(\r\n)", "<br />");
str  = str.replaceAll("(\n)", "<br />");

Disclaimer: this is not very efficient.

Answer 2

This should work. You need to put in two slashes

str = str.replaceAll("(\\r\\n|\\n)", "<br />");

In this Reference, there is an example which shows

private final String REGEX = "\\d"; // a single digit

I have used two slashes in many of my projects and it seems to work fine!

Answer 3

It works for me.

public class Program
{
    public static void main(String[] args) {
        String str = "This is a string.\nThis is a long string.";
        str = str.replaceAll("(\r\n|\n)", "<br />");
        System.out.println(str);
    }
}

Result:

This is a string.<br />This is a long string.

Your problem is somewhere else.

Answer 4

A little more robust version of what you're attempting:

str = str.replaceAll("(\r\n|\n\r|\r|\n)", "<br />");

Answer 5

It works for me. The Java code works exactly as you wrote it. In the tester, the input string should be:

This is a string.
This is a long string.

...with a real linefeed. You can't use:

This is a string.\nThis is a long string.

...because it treats \n as the literal sequence backslash 'n'.