Regex for checking if a string is strictly alphanumeric

Question

How can I check if a string contains only numbers and alphabets ie  is alphanumeric

User · Answer

Considering you want to check for ASCII Alphanumeric characters, Try this: "^[a-zA-Z0-9]*$". Use this RegEx in String.matches(Regex), it will return true if the string is alphanumeric, else it will return false.

public boolean isAlphaNumeric(String s){
    String pattern= "^[a-zA-Z0-9]*$";
    return s.matches(pattern);
}

If it will help, read this for more details about regex: http://www.vogella.com/articles/JavaRegularExpressions/article.html

User · Answer

Pattern pattern   Pattern compile    a-zA-Z0-9       Matcher matcher   pattern matcher  Teststring123    if matcher matches              yay  alphanumeric

User · Answer

It s 2016 or later and things have progressed  This matches Unicode alphanumeric strings       p IsAlphabetic   p IsDigit       See the reference  section  Classes for Unicode scripts  blocks  categories and binary properties    There s also this answer that I found helpful

User · Answer

try this  0-9a-zA-Z   for only alpha and num with one char at-least     may need modification so test on it   http   www regexplanet com advanced java index html  Pattern pattern   Pattern compile    0-9a-zA-Z       Matcher matcher   pattern matcher phoneNumber   if  matcher matches

User · Answer

See the documentation of Pattern   Assuming US-ASCII alphabet  a-z  A-Z   you could use  p Alnum    A regex to check that a line contains only such characters is      p Alnum        That also matches empty string  To exclude empty string       p Alnum

User · Answer

Use character classes       alnum

User · Answer

If you want to include foreign language letters as well  you can try   String string    hippopotamus   if  string matches      p L 0-9             string is alphanumeric do something here        Or if you wanted to allow a specific special character  but not any others  For example for   or space  you can try   String string     somehashtag   if string matches      p L 0-9              string is alphanumeric plus    do something here

User · Answer

To check if a String is alphanumeric  you can use a method that goes through every character in the string and checks if it is alphanumeric       public static boolean isAlphaNumeric String s               for int i   0  i  lt  s length    i                         char c   s charAt i                       if  Character isDigit c   amp  amp   Character isLetter c                               return false                            return true

User · Answer

In order to be unicode compatible      pL pN      where   pL stands for any letter  pN stands for any number

User · Answer

100  alphanumeric RegEx  it contains only alphanumeric  not even integers  amp  characters  only alphanumeric   For example      special char  not allowed    123  not allowed    asdf  not allowed    1235asdf  allowed      String name      lt a-zA-Z gt    d  a-zA-Z  a-zA-Z  d

[java] Regex for checking if a string is strictly alphanumeric

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