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

问题

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 ?

回答1:

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.

回答2:

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

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

回答3:

For me, this worked:

rawText.replaceAll("(\\\\r\\\\n|\\\\n)", "\\\n");

Tip: use regex tester for quick testing without compiling in your environment

回答4:

Since my account is new I can't up-vote Nino van Hooff's answer. If your strings are coming from a Windows based source such as an aspx based server, this solution does work:

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

Seems to be a weird character set issue as the double back-slashes are being interpreted as single slash escape characters. Hence the need for the quadruple slashes above.

Again, under most circumstances "(\\r\\n|\\n)" should work, but if your strings are coming from a Windows based source try the above.

Just an FYI tried everything to correct the issue I was having replacing those line endings. Thought at first was failed conversion from Windows-1252 to UTF-8. But that didn't working either. This solution is what finally did the trick. :)

回答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'.

回答6:

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.

回答7:

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!

来源：https://stackoverflow.com/questions/3056834/replace-n-and-r-n-with-br-in-java