help with making a password checker in java

Question

Hello, I am trying to make a program in Java that checks for three specific inputs. It has to be 1. At least 7 characters. 2. Contain both upper and lower case alphabetic characters. 3. Contain at least 1 digit. So far I have been able to make it check if there is 7 characters, but I am having trouble with the last two. What should I put in my loop as an if statement to check for digits and make it upper and lower case. Any help would be greatly appreciated. Here is what I have so far.

import java.awt.*;
import java.io.*;
import java.util.StringTokenizer;

public class passCheck
{


    private static String getStrSys ()
    {
        String myInput = null;          //Store the String that is read in from the command line

        BufferedReader mySystem;        //Buffer to store the input

        mySystem = new BufferedReader (new InputStreamReader (System.in)); //creates a connection to system input
        try
        {
            myInput = mySystem.readLine (); //reads in data from the console
            myInput = myInput.trim ();
        }
        catch (IOException e)  //check
        {
            System.out.println ("IOException: " + e);
            return "";
        }
        return myInput; //return the integer to the main program
    }


    //****************************************
    //main instructions go here
    //****************************************

    static public void main (String[] args)
    {

        String pass;         //the words the user inputs
        String temp = "";            //holds temp info

        int stringLength;          //length of string
        boolean goodPass = false;


        System.out.print ("Please enter a password: ");  //ask for words

        pass = getStrSys ();                              //get words from system
        temp = pass.toLowerCase ();
        stringLength = pass.length ();             //find length of eveyrthing



        while (goodPass == false)

            {
                if (stringLength < 7)
                {
                    System.out.println ("Your password must consist of at least 7 characters");
                    System.out.print ("Please enter a password: ");  //ask for words
                    pass = getStrSys ();
                    stringLength = pass.length ();
                    goodPass = false;
                }
                else if (something to check for digits)
                {







                }

            }

Answer 1

A regular expression is more appropriate for what you are trying to accomplish. For instance, using lookahead assertions, you'd use something like this:

Pattern p = Pattern.compile("^.*(?=.{7,})(?=.*[a-z])(?=.*[A-Z])(?=.*[0-9]).*$");
String pass = getStrSys();
Matcher m = p.matcher(pass);
if (m.matches()) {
  System.out.println("Valid password.");
} else {
  System.out.println("Invalid password.");
} 

Answer 2

1. Don't use StringTokenizer. Use String.split.
2. Use the functions in the Character class to check for upper case, lower case, or numeric.
3. Since you've forced lower case, you can't check. You need to get rid of that.