Question

I am trying to use the matches() function to check a user-entered password for certain conditions

“Contains six alphanumeric characters, at least one letter and one number”

Here is my current condition for checking for alphanumeric characters

pword.matches("([[a-zA-Z]&&0-9])*")

unfortunately in example using “rrrrZZ1” as the password this condition still returns false

What would be the correct regular expression? Thank you

Answer 1

Someone else here may prove me wrong, but this is going to be very difficult to do without an excessively complex regular expression. I’d just use a non-regular expression approach instead. Set 3 booleans for each of your conditions, loop through the characters and set each boolean as each condition is met, and if all 3 booleans don’t equal true, then fail the verification.

You could use something as simple as this:

public boolean validatePassword(String password){
    if(password.length() < 6){
        return false;
    }
    boolean foundLetter = false;
    boolean foundNumber = false;
    for(int i=0; i < password.length(); i++){
        char c = password.charAt(i);
        if(Character.isLetter(c)){
            foundLetter = true;
        }else if(Character.isDigit(c)){
            foundNumber = true;
        }else{
            // Isn't alpha-numeric.
            return false;
        }
    }
    return foundLetter && foundNumber;
}