Getting " when trying to replace a character in string

Question

I want to replace " from a string with ^.

String str = "hello \"there";
System.out.println(str);
String str1 = str.replaceAll("\"", "^");
System.out.println(str1);
String str2= str1.replaceAll("^", "\"");
System.out.println(str2);

and the output is :

hello "there
hello ^there
"hello ^there

why I am getting extra " in start of string and ^ in between string

I am expecting:

hello "there

hoan · Accepted Answer · 2018-03-27T15:17:56.467

9

the replaceAll() method consume a regex for the 1st argument.

the ^ in String str2= str1.replaceAll("^", "\""); will match the starting position within the string. So if you want the ^ char, write \^

Hope this code can help:

String str2= str1.replaceAll("\\^", "\"");

edited Mar 27 '18 at 15:17

answered Mar 27 '18 at 13:13

hoan

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Then how can i print the output i want – Kumar Harsh Mar 27 '18 at 13:14
Yes: use replace instead of replaceAll – Maurice Perry Mar 27 '18 at 13:14
@MauricePerry `String str2= str1.replaceAll("\\^", "\"");` should works you will "escape" ^ but `\` need to be also escaped :D – xxxvodnikxxx Mar 27 '18 at 13:16
@xxxvodnikxxx so would `String str2 = str1.replace("^", "\"");` and it's simpler – Maurice Perry Mar 27 '18 at 13:17
For this case will work also replace instead replace all, but ofc if you will want really to replace all in string, I mean if there will be more occurrence, then you can use it.. As obviously method name says. – xxxvodnikxxx Mar 27 '18 at 13:18
@KumarHarsh updated my answer. hope that can help your question. – hoan Mar 27 '18 at 13:54

Reimeus · Answer 2 · 2018-03-27T14:01:00.440

5

Try using replace which doesnt use regex

String str2 = str1.replace("^", "\"");

edited Mar 27 '18 at 14:01

answered Mar 27 '18 at 13:15

Reimeus

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or, similar char based `replace('^','"')` Both have better performance than regex versions – Jacek Cz Mar 27 '18 at 13:21

score 3 · Answer 3 · answered Mar 27 '18 at 13:15

3

^ means start of a line in regex, you can add two \ before it:

 String str2= str1.replaceAll("\\^", "\"");

The first is used to escape for compiling, the second is used to escape for regex.

answered Mar 27 '18 at 13:15

xingbin

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score 2 · Answer 4 · edited Mar 27 '18 at 15:36

2

Since String::replaceAll consumes regular expression you need to convert your search and replacement strings into regular expressions first:

str.replaceAll(Pattern.quote("\""), Matcher.quoteReplacement("^"));

edited Mar 27 '18 at 15:36

Hulk

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answered Mar 27 '18 at 13:37

jukzi

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score 0 · Answer 5 · answered Mar 27 '18 at 13:32

0

Why do you want to use replaceAll. Is there any specific reason ? If you can use replace function then try below String str2= str1.replace("^", "\"");

answered Mar 27 '18 at 13:32

Rmahajan

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Getting " when trying to replace a character in string

5 Answers5