I'm trying to replace all special characters with a "%", like:
"123.456/789" -> "123%465%798" my regular expression is:
[^a-zA-Z0-9]+ In online tools* it works perfecly, but in java
s.replaceAll("[^a-zA-Z0-9]+", "%"); strings remain untouched.
*I tried: http://www.regexplanet.com/ http://regex101.com/ and others
Strings are immutable. You forgot to reassign new String to the s variable :)
s = s.replaceAll("[^a-zA-Z0-9]+", "%"); // ^ this creates a new String 
dude are you all talking about ? :)replaceAll() like all methods in String class, DO NOT modify String on which you invoke a method. This is why we say that String is immutable object. If you want to 'modify' it, you need to do
s = s.replaceAll("[^a-zA-Z0-9]+", "%"); In fact you don't modify String s. What happens here is that new String object is returned from a function. Then you assign its reference to s.
You can't change a String, instead replaceAll returns a new value. so you should use it like this
String newStr = s.replace(...) Working code as per your expectations :)
import java.util.regex.Pattern; public class Regex { public static void main(String[] args) { String s = "123.456/789"; Pattern p = Pattern.compile("[^a-zA-Z0-9]+"); String newStr = s.replaceAll("[^a-zA-Z0-9]+", "%"); System.out.println(s + " -> " + newStr); } } Output : 123.456/789 -> 123%456%789
s = s.replaceAll("[^a-zA-Z0-9]+", "%");Strings are immutable.