How to replace special characters in a string?

I have a string with lots of special characters. I want to remove all those, but keep alphabetical characters.

How can I do this?

Solution 1:

That depends on what you mean. If you just want to get rid of them, do this:
(Update: Apparently you want to keep digits as well, use the second lines in that case)

String alphaOnly = input.replaceAll("[^a-zA-Z]+","");
String alphaAndDigits = input.replaceAll("[^a-zA-Z0-9]+","");

or the equivalent:

String alphaOnly = input.replaceAll("[^\\p{Alpha}]+","");
String alphaAndDigits = input.replaceAll("[^\\p{Alpha}\\p{Digit}]+","");

(All of these can be significantly improved by precompiling the regex pattern and storing it in a constant)

Or, with Guava:

private static final CharMatcher ALNUM =
  CharMatcher.inRange('a', 'z').or(CharMatcher.inRange('A', 'Z'))
  .or(CharMatcher.inRange('0', '9')).precomputed();
// ...
String alphaAndDigits = ALNUM.retainFrom(input);

But if you want to turn accented characters into something sensible that's still ascii, look at these questions:

• Converting Java String to ASCII
• Java change áéőűú to aeouu
• ń ǹ ň ñ ṅ ņ ṇ ṋ ṉ ̈ ɲ ƞ ᶇ ɳ ȵ --> n or Remove diacritical marks from unicode chars

Solution 2:

I am using this.

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

It replace all special characters from string.

Here

\w : A word character, short for [a-zA-Z_0-9]

\W : A non-word character

Solution 3:

You can use the following method to keep alphanumeric characters.

replaceAll("[^a-zA-Z0-9]", "");

And if you want to keep only alphabetical characters use this

replaceAll("[^a-zA-Z]", "");

Solution 4:

Replace any special characters by

replaceAll("\\your special character","new character");

ex:to replace all the occurrence of * with white space

replaceAll("\\*","");

*this statement can only replace one type of special character at a time