split this String using function split. Here is my code:
String data= "data^data";
String[] spli = data.split("^");
When I try to do that in spli contain only one string. It seems like java dont see "^" in splitting. Do anyone know how can I split this string by letter "^"?
EDIT
SOLVED :P
This is because String.split takes a regular expression, not a literal string. You have to escape the ^ as it has a different meaning in regex (anchor at the start of a string). So the split would actually be done before the first character, giving you the complete string back unaltered.
You escape a regular expression metacharacter with \, which has to be \\ in Java strings, so
data.split("\\^")
should work.
You need to escape it because it takes reg-ex
\\^
Special characters like ^ need to be escaped with \
This does not work because .split() expects its argument to be a regex. "^" has a special meaing in regex and so does not work as you expect. To get it to work, you need to escape it. Use \\^.
The reason is that split's parameter is a regular expression, so "^" means the beginning of a line. So you need to escape to ASCII-^: use the parameter "\\^".
Related
I am trying break a String in various pieces using delimiter(":").
String sepIds[]=ids.split(":");
It is working fine. But when I replace ":" with " * " and use " * " as delimiter, it doesn't work.
String sepIds[]=ids.split("*"); //doesn't work
It just hangs up there, and doesn't execute further.
What mistake I am making here?
String#split takes a regular expression as parameter. In regex some chars have special meanings so they need to be escaped, for example:
"foo*bar".split("\\*")
the result will be as you expect:
[foo, bar]
You could also use the method Pattern#quote to simplify the task.
"foo*bar".split(Pattern.quote("*"))
String.split expects a regular expression argument. * has got a meaning in regex. So if you want to use them then you need to escape them like this:
String sepIds[]=ids.split("\\*");
The argument of .split() is a regular expression, not a string literal. Therefore you need to escape * since it is a special regex character. Write:
ids.split("\\*");
This is how you would split agaisnt one or more spaces:
ids.split("\\s+");
Note that Guava has Splitter which is very, very fast and can split against literals:
Splitter.on('*').split(ids);
'*' and '.' are special characters you have to blackshlash it.
String sepIds[]=ids.split("\\*");
To read more about java patterns please visit that page.
That is expected behaviour. The documentation for the String split function says that the input string is treated as a regular expression (with a link explaining how that works). As Germann points out, '*' is a special character in regular expressions.
Java's String.split() uses regular expressions to split up the string (unlike similar functions in C# or python). * is a special character in regular expressions and you need to escape it with a \ (backslash). So you should use instead:
String sepIds[]=ids.split("\\*");
You can find more information on regular expressions anywhere on the internet a quite complete list of special characters supported by java should be here: http://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html
I want to convert all the occurences of \" in a text file into empty string.
So basically I want to convert to .
I used the following method but it doesnt seem to work:
sb.toString().replaceAll("\\"", "");
Can anyone help me with this?
sb.toString().replaceAll(Pattern.quote("\\""), "");
How about instead of replaceAll which uses regex, use simple replace which will automatically escape all regex metacharacters (like in your case "\\") in pattern you want to replace.
String replaced = sb.toString().replace("\\"", "");
Your problem is that in a regular expression, the \ character has a special meaning. You need to escape it with a second \. Then both \ characters need to be escaped from the Java compiler. You actually need to write
sb.toString().replaceAll("\\\\"", "");
I am trying to execute the following operation on a String.
if (combatLog.contains("//*name//*")) {
combatLog.replaceAll("//*name//*",glad.target.name);
}
The slashes are my attempt to escape the *, as it doesn't work without them. I have also tried one slash, and slashes on contains or replaceAll individually. Thanks
replaceAll() (counter-intuitively) takes a regex, not a string.
To escape a character for a regex, you need a double-backslash (doubled to escape the backslash from the string literal).
However, you don't want a regex. You should simply call replace() instead, which won't need any escaping.
You're using forward slashes. The backslash is the escape character. Furthermore, unless the string is being used for regex or something similar, you need not escape the *, or the / if thats what you're trying to escape.
If combatLog is a String, its contains method checks for a sequence of characters only. If you're looking for *name* in the string, you only need call combatLog.contains("*name*").
You are using forward slashes use the backslash: \ to escape characters
[edit]
also as slaks said you need to use replace() which accepts a string as input rather than a regex.
Don't forget about immutability of strings, and reassign the newly created string. Also, if your if block doesn't contain any more code, you don't need the if check at all.
You have 3 options:
if (combatLog.contains("*name*")) { // don't escape in contains()
combatLog = combatLog.replaceAll("\\*name\\*", replacement);// correct escape
}
// another regex based solution
if (combatLog.contains("*name*")) {
combatLog = combatLog.replaceAll("[*]name[*]", replacement);// character class
}
or without a regex
if (combatLog.contains("*name*")) {
combatLog = combatLog.replace("*name*", replacement);// literal string
}
I want to split function in java.But it s not working good.
String mystring = "ersin#$gulbahar#$ev";
String [] scripts= mystring.split("#$"); //it does not split.
how can i fix this?
String mystring = "ersin#$gulbahar#$ev";
String[] scripts = mystring.split("#\\$");
System.out.println(Arrays.toString(scripts));
OUTPUT:
[ersin, gulbahar, ev]
try this:
mystring.split("#\\$")
the split method uses a Regex to split the text, a $ character has other mean in a regex
split takes a regular expression as a parameter, and $ is a special character in a regular expression meaning "match the end of the string".
Since you want to match a literal $, not the end of the string, you need to escape it with a backslash: mystring.split("#\\$"); should work.
Escape $ in your expression: split() takes a regular expression as parameter! Common issue...
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;