More Efficient Password Checker

Question

The program I have been assigned has the following rules:

rules:

1. number of chars must be in [6, 10]

2.there must be >= 2 chars in the range ['a', 'z']

3.there must be >= 2 chars in the range ['A', 'Z']

4. there must be >= 2 chars in the range ['0', '9']

For example, pw1("aaBC09-+") should return true, and pw1("aabC09-+") should return false.

I have attached my code but is there a more efficient / cleaner code I could be using?

import java.util.*;

public class PassChecker2 {

public static void main(String[] args) {

Scanner input = new Scanner(System.in);

// Prompt User to Enter String
System.out.print("Enter Password: ");

// Grab User Generated String
String pw = input.next();

// Pass String to be Checked
boolean valid_pw = checkPW(pw);

if(valid_pw)
  System.out.println(pw + " is a valid password!");
else
  System.out.println(pw + " is not a valid password!");

}

public static boolean checkPW(String pw)
{

int pwLowerCase = 0,
     pwUpperCase = 0,
     pwNumber = 0;

// Return False if PW is too Small / Large
if(!(pw.length() >= 2 && pw.length() <= 10))
    return false;

for(int position = 0; position < pw.length(); ++position)
{

    char character = pw.charAt(position);

    if(character >= 'a' && character <= 'z')
        ++pwLowerCase;
    else if(character >= 'A' && character <= 'Z')
        ++pwUpperCase;
    else if(character >= '1' && character <= '9')
        ++pwNumber;

}

return (pwLowerCase >= 2 && pwUpperCase >= 2 && pwNumber >= 2);

}

}

Answer 1

IMHO, we can use regex expression for password checking, instead of writing java code:

^(?=.*[A-Z].*[A-Z])(?=.*[0-9].*[0-9])(?=.*[a-z].*[a-z]).{6,10}$

check if the expression fullfil your demand here:

a Ruby regular expression editor

You can then employ Matcher and Pattern in java.util.regex package to use the regex expression

Advantage of regex:

the can be reused accross different languages. Say for a website development we may use both client-side checking and server-side checking, we don't write the checker for both javascript and java-backend, but employ regex expression in both side.