replaceAll () function Scanner in Java

Question

I want to replace the \n character with a space. The below code in not working. Any suggestions?

System.out.println("Enter a string:");
    Scanner sc=new Scanner(System.in);
    String str=sc.nextLine().toString();
    //String str="one\ntwo";
    if(str.contains("\\n")){
        System.out.println("yes");
        str=str.replaceAll("\\n", " " );
    }
    System.out.println("str : "+str);

The input string is one\ntwo

possible duplicate of [replace \n and \r\n with
in java](http://stackoverflow.com/questions/3056834/replace-n-and-r-n-with-br-in-java) — Kick Buttowski, Oct 05 '14 at 18:14

score 3 · Answer 1 · edited May 23 '17 at 12:12

replaceAll("\\n", " " ) uses regex as first argument and "\\n" is treated by Java regex engine as \n which represents line separator, not \ and n characters. If you want to replace \n literal (two characters) you either need to

escape \ in regex itself by replaceAll("\\\\n", " " );
use replace instead of replaceAll which will do escaping for you

Preferred way is using

str = str.replace("\\n", " " );

BTW sc.nextLine() already returns String, so there is no need for

sc.nextLine().toString();
//           ^^^^^^^^^^^ this part is unnecessary

Rustam · Accepted Answer · 2014-10-05T18:17:18.990

1

try this :

str=str.replaceAll("\\\\n", " " );

OR

 str=str.replace("\\n", " " );

edited Oct 05 '14 at 18:17

answered Oct 05 '14 at 18:11

Rustam

6,307
1
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score 0 · Answer 3 · edited May 23 '17 at 11:56

0

Your condition is not good

if(str.contains("\\n")) -> if(str.contains("\n"))

all it describe here : https://stackoverflow.com/a/5518515/4017037

edited May 23 '17 at 11:56

Community

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answered Oct 05 '14 at 18:19

stacky

715
5
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It seems that OP doesn't have `\n` (line separator) in String, but `"\\n"` ``\`` character followed by `n`. – Pshemo Oct 05 '14 at 18:20

replaceAll () function Scanner in Java

3 Answers3