44

How can I do a string replace of a back slash.

Input Source String:

sSource = "http://www.example.com\/value";

In the above String I want to replace "\/" with a "/";

Expected ouput after replace:

sSource = "http://www.example.com/value";

I get the Source String from a third party, therefore I have control over the format of the String.

This is what I have tried

Trial 1:

sSource.replaceAll("\\", "/");

Exception Unexpected internal error near index 1 \

Trial 2:

 sSource.replaceAll("\\/", "/");

No Exception, but does not do the required replace. Does not do anything.

Trial 3:

 sVideoURL.replace("\\", "/");

No Exception, but does not do the required replace. Does not do anything.

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3
  • btw, you source cannot be \/ if you declare it as a string literal. But I will assume it is coming from somewhere else. Commented Apr 8, 2011 at 14:27
  • In your example, you replace \ with nothing, not with /; there is already a forward slash. Commented Apr 8, 2011 at 14:28
  • possible duplicate of Backslash problem with String.replaceAll Commented May 26, 2011 at 8:38

8 Answers 8

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56 
sSource = sSource.replace("\\/", "/");
  • String is immutable - each method you invoke on it does not change its state. It returns a new instance holding the new state instead. So you have to assign the new value to a variable (it can be the same variable)
  • replaceAll(..) uses regex. You don't need that.
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Comments

39

Try replaceAll("\\\\", "") or replaceAll("\\\\/", "/").

The problem here is that a backslash is (1) an escape chararacter in Java string literals, and (2) an escape character in regular expressions – each of this uses need doubling the character, in effect needing 4 \ in row.

Of course, as Bozho said, you need to do something with the result (assign it to some variable) and not throw it away. And in this case the non-regex variant is better.

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14

Try

 sSource = sSource.replaceAll("\\\\", "");

Edit : Ok even in stackoverflow there is backslash escape... You need to have four backslashes in your replaceAll first String argument...

The reason of this is because backslash is considered as an escape character for special characters (like \n for instance).
Moreover replaceAll first arg is a regular expression that also use backslash as escape sequence.
So for the regular expression you need to pass 2 backslash. To pass those two backslashes by a java String to the replaceAll, you also need to escape both backslashes.
That drives you to have four backslashes for your expression! That's the beauty of regex in java ;)

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3 Comments

Won't work. use replace() instead of replaceAll() or use four backslashes
For stackoverflow syntax, use `` or four spaces in front to disable parsing (and format it as code).
Yep I didn't see that my backslashes were not escaped :) I edited my answer
7 
s.replaceAll ("\\\\", "");

You need to mask a backslash in your source, and for regex, you need to mask it again, so for every backslash you need two, which ends in 4.

But 

s = "http://www.example.com\\/value";

needs two backslashes in source as well.

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Comments

5

This will replace backslashes with forward slashes in the string:

source = source.replace('\\','/');
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1 Comment

Plain and simple :D and no regexp ;)
2

you have to do

sSource.replaceAll("\\\\/", "/");

because the backshlash should be escaped twice one for string in source one in regular expression

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1

To Replace backslash at particular location:

if ((stringValue.contains("\\"))&&(stringValue.indexOf("\\", location-1)==(location-1))) { stringValue=stringValue.substring(0,location-1); }
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0 
 sSource = StringUtils.replace(sSource, "\\/", "/")
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1 Comment

Could you explain what was wrong with OP's code and why this one is better to use?

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