How to replace "?" in a string

[weishan zhang]

String s="aasddd??dsfas?df";
s.replaceAll("?","");
I always got the error "java.util.regex.PatternSyntaxException: Dangling meta character '?' near index 0".
And "\?" will not work of course.
I do not want to transform to StringBuffer or char array.
Thanks,

[Nayanjyoti Talukdar]

Hi,
There is no any method called "replaceAll" in String class of Java API. Try this code

String s="aasddd??dsfas?df";
s.replace('?','\0');

Hope this helps!!
Nayan.

[weishan zhang]

Hi,
Thank you for you reply but the error remains the same.
"replaceAll()" start since jdk1.4.

[Nayanjyoti Talukdar]

Hey, I'm using jdk1.3, and I tried the code just before I sent u. It worked perfectly fine. I've not used jdk1.4. So, check out all the available methods in jdk1.4 API for replacing character from a String.
-----------
Nayan.

[Jon Strayer]

Use a double backslash:

 String s="aasddd??dsfas?df";
s.replaceAll("\\?",""); 

[Jim Yingst]

Jon is right of course. See the 1.4 API for String and follow the links to "regular expression" for more details. Basically, it turns out ? is a special character in regular expressions, and needs a preceeding \ as an escape sequence. As it happens, \ is also a special character in Java string literals, and to create a normal \ you need another preceeding \ as an escape sequence. So combining these rules you need "\\?" to represent a single ? char in a pattern. Very I know - but that's the way it is.
[ January 09, 2003: Message edited by: Jim Yingst ]

[Jasper Vader]

i found this interesting and so tried it at home on my very own computer and although it compiled, when i tried to print the output the question marks were still there...here is the bit of code -

class Print2Screen
{
public static void main (String[] args)
{
String s = "what??";
s.replaceAll("\\?","");
System.out.print(s);
}
}
is it because the reference of 's' refers to the initial value that was assigned to the String variable?

[Jim Yingst]

Strings are immutable. This means that methods that look like they should change the string are really creating new strings, which has no direct effect on the original string. So yes, s still refers to the original value "what??". To forget the old value of s and use hte replaced value instead:

  s = s.replaceAll("\\?","");

[Jasper Vader]

cool, thanks Jim