Java RegEx - Remove All Special Characters from String

Java RegEx – Remove All Special Characters from String example shows how to remove all special characters from a string using regex pattern in Java.

How to remove special characters from a string using a regex pattern?

There are many cases where we do not want to have any special characters inside string content. For example, in user-generated content or in the string used for id.

If there is a fixed list of characters you do not want in the string, you can simply list all of them in a character class and remove all of them using the string replaceAll method. For example, if you do not want any of the “@!#$” characters, you can use below given regex pattern.

System.out.println( "abcd123".replaceAll("[@!#$]", "") );

System.out.println( "A@1".replaceAll("[@!#$]", "") );

System.out.println( "=abc@xyz12$$!#$adf".replaceAll("[@!#$]", "") );

Output

abcd123

=abcxyz12adf

As you can see from the output, the regex pattern removed all the characters we specified in the character class from the string data. However, the “=” was not removed from the last string since it was not on our list of characters.

Use the above-given approach if you have a limited number of blacklist characters that you do not want to keep in the string. If you want to remove all the special characters, you can simply use the below-given pattern.

1	[^a-zA-Z0-9]

The pattern means not any character between a to z, A-Z, and 0 to 9. That basically means it will remove everything except the characters we specified when we use it to replace the match with an empty string.

package com.javacodeexamples.regex;

public class RegExRemoveSpecialCharacters {

public static void main(String[] args) {

String[] strContent = {

"abcABC",

"123",

"AB@CD$",

"a~!@#$%^&*(){}+=\\|?/<>,.:;'",

};

String pattern = "[^a-zA-Z0-9]";

for(String str : strContent) {

System.out.println( str.replaceAll(pattern, "") );

}

Output

abcABC

123

ABCD

As you can see from the output, all the special characters were removed from the string this time.

Important Note:

The above-given pattern removes everything that is not a character or a digit. If you want to allow a few or some of the characters e.g. an underscore you can mention that in the character class. See the below-given pattern.