help with making a password checker in java

I am trying to make a program in Java that checks for three specific inputs. It has to have pass these tests:开发者_高级运维

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 */)
                {

                }

            }

---

Sure you can come up with a convoluted—almost unreadable—regex for doing this but I wouldn't suggest it. Apart from the readability aspect, if the password fails it doesn't tell you why. This solves both of these problems:

while (true) {
  pass = getStrSys();
  if (pass.length() < 7) {
    System.out.println("must be at least 7 characters long");
  } else {
    boolean upper = false;
    boolean lower = false;
    boolean number = false;
    for (char c : pass.toCharArray()) {
      if (Character.isUpperCase(c)) {
        upper = true;
      } else if (Character.isLowerCase(c)) {
        lower = true;
      } else if (Character.isDigit(c)) {
        number = true;
      }
    }
    if (!upper) {
      System.out.println("must contain at least one uppercase character");
    } else if (!lower) {
      System.out.println("must contain at least one lowercase character");
    } else if (!number) {
      System.out.println("must contain at least one number");
    } else {
      break;
    }
  }
}

---

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.");
} 

---

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.

---

In your situation. There should be two condition true for validation. I think following will be the best approach to achieve it.

private static final char[] SPECIAL = "$!+\-#?_%&/".toCharArray();
private static final char[] NUMBER = "0123456789".toCharArray();


public static boolean checkValidation(String password)
{
    int points = 0;
    String lowerPass = password.toLowerCase();
    String upperPass = password.toUpperCase();
    if(!password.equals(lowerPass) && !password.equals(upperPass))
    {
        // if contains upper or lower letter
        points++;
    }

    if(contains(password, SPECIAL))
    {
        // if it contains special character
        points++;
    }
    if(contains(password, NUMBER))
    {
        // if it contains Number
        points++;
    }

    return points >= 2;
}


public static boolean contains(String pwd, char[] value)
{
    int i = 0;
    boolean success = false;
    while(i < value.length && !success)
    {
        if(pwd.indexOf(""+value[i]) != -1)
        {
            success = true;
        }
        i++;
    }
    return success;
}