CODEWITHSUNDEEP
javaregex
Java Questions
Java Questions

Reputation: 7953

allow only Alphanumeric values using java

i need to get the value which only Alphanumeric and it can be of anything which comes under this

1. asd7989 - true
2. 7978dfd - true
3. auo789dd - true
4. 9799 - false
5.any special characters - false

i tried with the following but it does not give expected result

import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.apache.struts.action.ActionMessage;

public class Test {

  public static void main(String[] args) {

      Pattern pattern = Pattern.compile("^[0-9a-zA-Z]+$");
      Matcher matcher = pattern.matcher("465123");
      if(matcher.matches()) {
           System.out.println("match");
      }else{
          System.out.println("not match");
      }
  }
}

the result should actually be not match but i get as match

Upvotes: 1

Views: 1242

Answers (3)

Casimir et Hippolyte
Casimir et Hippolyte

Reputation: 89557

You can use this pattern (with case insensitive option):

\A(?>[0-9]+|[A-Z]+)[A-Z0-9]+\z

The idea is to use the greediness and an atomic group to be sure that the characters matched in the group are different from the first character matched outside the group.

Note: with the matches() method, you can remove the anchors, since they are implicit.

Upvotes: 1

Avinash Raj
Avinash Raj

Reputation: 174696

You don't need to include the start and end anchors while passing your regex to matches method.

[0-9a-zA-Z]*[a-zA-Z][0-9a-zA-Z]*[0-9][0-9a-zA-Z]*|[0-9a-zA-Z]*[0-9][0-9a-zA-Z]*[A-Za-z][0-9a-zA-Z]*

Upvotes: 1

anubhava
anubhava

Reputation: 785058

You need to use lookahead for this regex:

^(?=.*?[a-zA-Z])(?=.*?[0-9])[0-9a-zA-Z]+$

RegEx Demo

Lookaheads will ensure that at least one alphabet and at least one digit is present in the input string.

Upvotes: 1

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