remove all special characters in java

Question

Possible Duplicate    Replacing all non-alphanumeric characters with empty strings       import java util Scanner  import java util regex    public class io  public static void main String args     Scanner scan   new Scanner System in   String c  if  c scan nextLine     null     Pattern pt   Pattern compile    a-zA-Z0-9     Matcher match  pt matcher c       while match find              c c replace Character toString c charAt match start                         System out println c                    Case 1  Input   hjdg h amp jk8 i0ssh6 Expect   hjdghjk8i0ssh6 Output   hjdgh amp jk8 issh6   Case 2  Input   hjdgh amp jk8i0ssh6 Expect   hjdghjk8i0ssh6 Output   hjdghjk8i0ssh6   Case 3  Input   hjdgh amp j amp k8i0ssh6 Expect   hjdghjk8i0ssh6 Output   hjdghjki0ssh6   Anyone please help me to figure out  what is wrong in my code logic

User · Answer

Your problem is that the indices returned by match.start() correspond to the position of the character as it appeared in the original string when you matched it; however, as you rewrite the string c every time, these indices become incorrect.

The best approach to solve this is to use replaceAll, for example:

        System.out.println(c.replaceAll("[^a-zA-Z0-9]", ""));

User · Answer

use    W   or    a-zA-Z0-9   as regex to match any special characters and also use String replaceAll regex  String  to replace the spl charecter with an empty string  remember as the first arg of String replaceAll is a regex you have to escape it with a backslash to treat em as a literal charcter             String c   hjdg h amp jk8 i0ssh6           Pattern pt   Pattern compile    a-zA-Z0-9             Matcher match  pt matcher c           while match find                          String s  match group            c c replaceAll      s                         System out println c

User · Answer

You can read the lines and replace all special characters safely this way   Keep in mind that if you use   W you will not replace underscores  Scanner scan   new Scanner System in    while scan hasNextLine         System out println scan nextLine   replaceAll  quot   a-zA-Z0-9  quot    quot  quot

[java] remove all special characters in java

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