java replaceAll not working for \n characters

Question

I have a string like this: John \n Barber now I want to replace \n with actual new line character so it will become

John

Barber

this is my code for this

replaceAll("\\n", "\n");

but it is not working and giving me same string John \n Barber

Astrophotography

i think use replaceAll("\\\\n","\\n"); – Fortify

Answer 1

You need to do:

replaceAll("\\\\n", "\n");

The replaceAll method expects a regex in its first argument. When passing 2 \ in java string you actually pass one. The problem is that \ is an escape char also in regex so the regex for \n is actualy \\n so you need to put an extra \ twice.

Pahari

Answer 2

Since \n (or even the raw new line character U+000A) in regex is interpreted as new line character, you need \\n (escape the \) to specify slash \ followed by n.

That is from the regex engine's perspective.

From the compiler's perspective, in Java literal string, you need to escape \, so we add another layer of escaping:

String output = inputString.replaceAll("\\\\n", "\n");
//                                      \\n      U+000A

Gerstner

when i tried this way its working,String x="x\ny"; String y=x.replaceAll("\\n", "\n"); System.out.println(y); – Pollerd

@javaBeginner: Your original string contains the new line already. – Gerstner

isnt this same way that of OP? – Pollerd

@javaBeginner: No. OP's raw string contains a \ followed by n, which means in Java literal, it would be "something\\nsomething" – Gerstner

I am confused,still +1 for this answer – Pollerd

@javaBeginner: OP's string contains \ followed by an n. That is the difference here. If you want to make it clear, try to write a program that take input from command prompt, and use the replaceAll on it. – Gerstner

Answer 3

You need to escape \ character. So try

replaceAll("\\\\n", "\n");

Chrisman

Answer 4

replaceAll is using Regular Expressions, you can use replace which will also replace all '\n':

replace("\\\\n", "\n");

Shutz