Regex expression for password rules

Question

I have a requirement for password rules. Following are the rules.

The password must follow the following guidelines:

• Be at least eight characters long<

Answer 1

Here's how I would do it:

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

public class ValidatePassword
{
    public static void main (String[] args)
    {
        String pw = "abaslkA3FLKJ";

        // create an array with 4 regex patterns

        Pattern [] patternArray = {
            Pattern.compile("[a-z]"),
            Pattern.compile("[A-Z]"),
            Pattern.compile("[0-9]"),
            Pattern.compile("[&%$#]")
        };

        int matchCount = 0;

        // iterate over the patterns looking for matches

        for (Pattern thisPattern : patternArray) {
            Matcher theMatcher = thisPattern.matcher(pw);        
            if (theMatcher.find()) {
                matchCount ++;
            }
        }

        if (matchCount >= 3) {
            System.out.println("Success");
        }

        else {
            System.out.println("Failure: only " + matchCount + " matches");
        }
    }
}

I only added a few special characters to the 4th pattern... You'll have to modify it for your needs. You may need to escape certain characters with a backslash. You may also want to add other constraints like checking for no spaces. I'll leave that up to you.