I'm trying to replace the beginning of a string with backslashes to something else.
For some weird reason the replaceAll function doesn't like backslashes.
String jarPath = "\\\\xyz\\abc\\wtf\\lame\\";
jarPath = jarPath.replaceAll("\\\\xyz\\abc", "z:");
What should I do to solve this issue.
Thank you.
You need to double each backslash (again) as the Pattern class that is used by replaceAll() treats it as a special character:
String jarPath = "\\\\xyz\\abc\\wtf\\lame\\";
jarPath = jarPath.replaceAll("\\\\\\\\xyz\\\\abc", "z:");
A Java string treats backslash as an escape character so what replaceAll sees is: \\\\xyz\\abc. But replaceAll also treats backslash as an escape character so the regular expression becomes the characters: \ \ x y z \ a b c
Its doesn't like it because \ is the escape character in C like languages (even as an escape on this forum) Which makes it a poor choice for a file seperator but its a change they introduced in MS-DOS...
The problem you have is that you have escape the \ twice so \\host\path becomes \\\\host\\path in the string but for the regex has to be escaped again :P \\\\\\\\host\\\\path
If you can use a forward slash this is much simpler
String jarPath = "//xyz/abc/wtf/lame/";
jarPath = jarPath.replaceAll("//xyz/abc", "z:");
replaceAll() uses regexps which uses the backslash as an escape character. Moreover, Java String syntax also uses the backslash as an escape character. This means that you need to double all your backslashes to get what you want:
String jarPath = "\\\\xyz\\abc\\wtf\\lame\\";
jarPath = jarPath.replaceAll("\\\\\\\\xyz\\\\abc", "z:");
replaceAll expects a regular expression as its input string, which is then matched and replaced in every instance. A backslash is a special escape character in regular expressions, and in order to match it you need another backslash to escape it. So, to match a string with "\", you need a regular expression with '"\"`.
To match the string "\\\\xyz\\abc" you need the regular expression "\\\\\\\\xyz\\\\abc" (note an extra \ for each source \):
String jarPath = "\\\\xyz\\abc\\wtf\\lame\\";
jarPath = jarPath.replaceAll("\\\\\\\\xyz\\\\abc", "z:");
The replaceAll method uses regular expressions, which means that you have to escape slashes. In your case it might make sense to use String.replace instead:
String jarPath = "\\\\xyz\\abc\\wtf\\lame\\";
jarPath = jarPath.replace("\\\\xyz\\abc", "z:");
jarPath = jarPath.replaceAll("\\\\\\\\xyz\\\\abc", "z:");
For each '\' in your string you should put '\\' in the replaceAll method.
You can just use the replace method instead replaceAll in your use-case. If i'm not mistaken it's does not use regex.
You can use replace() method also which will remove \\\\xyz\\abc from the String
String jarPath = "\\\\xyz\\abc\\wtf\\lame\\";
jarPath = jarPath.replace("\\\\xyz\\abc", "z:");
Just got into a similar problem.
If you use backslash() in the second section of the replaceAll function, the backslashes will dissapear, to avoid that, you can use Matcher class.
String assetPath="\Media Database\otherfolder\anotherdeepfolder\finalfolder";
String assetRemovedPath=assetPath.replaceAll("\\\\Media Database(.*)", Matcher.quoteReplacement("\\Media Database\\_ExpiredAssets")+"$1");
system.out.println("ModifiedPath:"+assetRemovedPath);
Prints:
\Media Database\_ExpiredAssets\otherfolder\anotherdeepfolder\finalfolder
hope it helps!
Related
I have a String representing a directory, where \ is used to separate folders. I want to split based on "\\":
String address = "C:\\saeed\\test";
String[] splited = address.split("\\");
However, this is giving me a java.util.regex.PatternSyntaxException.
As others have suggested, you could use:
String[] separated = address.split("\\\\");
or you could use:
String[] separated = address.split(Pattern.quote("\\"));
Also, for reference:
String address = "C:\saeed\test";
will not compile, since \s is not a valid escape sequence. Here \t is interpreted as the tab character, what you actually want is:
String address = "C:\\saeed\\test";
So, now we see that in order to get a \ in a String, we need "\\". The regular expression \\ matches a single backslash since \ is a special character in regex, and hence must be escaped. Once we put this in quotes, aka turn it into a String, we need to escape each of the backslashes, yielding "\\\\".
String#split() method takes a regex. In regex, you need to escape the backslashes. And then for string literals in Java, you need to escape the backslash. In all, you need to use 4 backslashes:
String[] splited = address.split("\\\\");
\ has meaning as a part of the regex, so it too must be quoted. Try \\\\.
The Java will have at \\\\, and produce \\ which is what the regex processor needs to obtain \.
You need to use \\\\ instead of \\.
The backslash(\) is an escape character in Java Strings.If you want to use backslash as a literal you have to type \\\\ ,as \ is also a escape character in regular expressions.
For more details click here
Use separators:
String address = "C:\saeed\test";
String[] splited = address.split(System.getProperty("file.separator"));
The line
System.out.println("\\");
prints a single back-slash (\). And
System.out.println("\\\\");
prints double back-slashes (\\). Understood!
But why in the following code:
class ReplaceTest
{
public static void main(String[] args)
{
String s = "hello.world";
s = s.replaceAll("\\.", "\\\\");
System.out.println(s);
}
}
is the output:
hello\world
instead of
hello\\world
After all, the replaceAll() method is replacing a dot (\\.) with (\\\\).
Can someone please explain this?
When replacing characters using regular expressions, you're allowed to use backreferences, such as \1 to replace a using a grouping within the match.
This, however, means that the backslash is a special character, so if you actually want to use a backslash it needs to be escaped.
Which means it needs to actually be escaped twice when using it in a Java string. (First for the string parser, then for the regex parser.)
The javadoc of replaceAll says:
Note that backslashes ( \ ) and dollar signs ($) in the replacement
string may cause the results to be different than if it were being
treated as a literal replacement string; see Matcher.replaceAll. Use
Matcher.quoteReplacement(java.lang.String) to suppress the special
meaning of these characters, if desired.
This is a formatted addendum to my comment
s = s.replaceAll("\\.", Matcher.quoteReplacement("\\"));
IS MORE READABLE AND MEANINGFUL THAN
s = s.replaceAll("\\.", "\\\\\\");
If you don't need regex for replacing and just need to replace exact strings, escape regex control characters before replace
String trickyString = "$Ha!I'm tricky|.|";
String safeToUseInReplaceAllString = Pattern.quote(trickyString);
The backslash is an escape character in Java Strings. e.g. backslash has a predefined meaning in Java. You have to use "\ \" to define a single backslash. If you want to define " \ w" then you must be using "\ \ w" in your regex. If you want to use backslash you as a literal you have to type \ \ \ \ as \ is also a escape character in regular expressions.
I believe in this particular case it would be easier to use replace instead of replace all.
Reverend Gonzo Has the correct answer when he talks about escaping the character.
Using replaceAll:
s = s.replaceAll("\\.", "\\\\\\\\");
Using replace:
s = s.replaceAll(".", "\\");
replace just takes a string to match to, not a regular expression.
I don't like this implementation of regex. We should be able to escape characters with a single '\' , not '\'. But anyway if you want to get THIS.Out_Of_That you can do:
String prefix = role.replaceFirst("(\\.).*", "");
So you get prefix = THIS;
I have a URL string
http:\/\/a0.twimg.com\/profile_images\/2170585961\/ETimes_normal.png
I want replace "\" by "" but I use:
String.replaceAll("\","");
And it display error. How do i must?
(Retreived from this url key profile_image_url)
Escape the backslash with another backslash:
String.replaceAll("\\\\","");
As the first argument is a regular expression, there should be two backslashes (\ is a special character in regex). But it's also a string, so each backslash should be escaped. So there are four \s.
Use String.replace(CharSequence, CharSequence) instead, it repleaces all occurrences!
str = str.replace("\\", "");
From your example:
String u = "http:\\/\\/a0.twimg.com\\/profile_images\\/2170585961\\/ETimes_normal.png";
System.out.println(u.replace("\\",""));
Outputs:
http://a0.twimg.com/profile_images/2170585961/ETimes_normal.png
Note that String.replaceAll method takes a regular expression and in this case you don't need it..
I have to make below statement as string.i am trying,but it's giving invalid character sequence.I know it is basic,But not able to do this.any help on this appreciated.
String str="_1";
'\str%' ESCAPE '\'
Output should be: '\_1%' ESCAPE '\'.
Thanks,
Chaitu
String result = "'\\" + str + "%' ESCAPE '\\'";
Inside a string, a backslash character will "escape" the character after it - which causes that character to be treated differently.
Since \ has this special meaning, if you actually want the \ character itself in the string, you need to put \\. The first backslash escapes the second, causing it to be treated as a literal \ inside the string.
Knowing this, you should be able to construct the resulting string you need. Hope this helps.
String str="_1";
String source = "'\\str%' ESCAPE '\\'";
String result = source.replaceAll("str", str);
Another way to implement string interpolation. The replaceAll function finds all occurrences of str in the source string and replaces them by the passed argument.
To encode the backslash \ in a Java string, you have to duplicate it, because a single backslash works as an escape character.
Beware that the first argument if replaceAll is actually a regular expression, so some characters have a special meaning, but for simple words it will work as expected.
String str="_1";
String output = String.format("'\\%s%%' ESCAPE '\\'",str);
System.out.println(output);//prints '\_1%' ESCAPE '\'
My eventual goal is to have a string like
def newline = 'C:\\www\web-app\StudyReports\\test.bat'
but my old line only has one '\'.
I tried different ways of using the following:
def newline = oldline.replaceAll(/\\/,'//')
but that did not compile.
If I were you, I would replace the backslashes with forward slashes:
def newline=oldline.replaceAll(/\\+/, '/')
Both Java and Windows will accept the forward slash as a file separator, and it's lot easier to work with.
In Java, you'd use the String.replace(CharSequence target, CharSequence replacement), which is NOT regex-based.
You'd write something like:
String after = before.replace("\\", "\\\\");
This doubles up every \ in before.
String path = "1\\2\\\\3\\4";
System.out.println(path);
path = path.replace("\\", "\\\\");
System.out.println(path);
The output of the above is (as seen on ideone.com)
1\2\\3\4
1\\2\\\\3\\4
To match a single backslash in Java or Groovy, you have to enter it 4 times, because both the compiler and the regex engine use the backslash as the escape character. So if you enter "\\\\" as a String in Java, the compiler generates the string containing the two characters \\, which the regex engine interprets as a match for exactly one backslash \.
The replacement string must be escaped twice too, so you have to enter 8 backslashes as the replacement string.