Thread: Password Program

Check out String (Java Platform SE 6) and Character (Java Platform SE 6) for useful functions.

The program prompts the user to create a password, which they must then reenter to validate. If they match, the password is saved into a text file on my computer. If not, they repeat the process until they do, or until they hit cancel on the dialog box.
I need to figure out a way to implement rules when the user creates passwords in order to have them more secure. For example what I was thinking is forcing the user to create a password that is at least 7 characters long, and also for them to use both letters AND numbers. However I am not sure how I would go about the letters and numbers part of coding.

Did you read through the APIs for String and Character? Did you see anything useful?

I did
I have modified my program to make sure the password is at least 7 characters long, however I am still trying to figure out which constructors I could use in order to check whether the password has more than just letters. My program currently:

 import java.io.*;
import javax.swing.*;
 
public class PasswordModified{
  public static void main(String[] args)
      throws FileNotFoundException{
    String pw1;
    String pw2;
    int length;
    PrintStream output = new PrintStream(new File("C:\\Programs\\Lab5\\password.txt"));
    do{
      pw1 = JOptionPane.showInputDialog("Enter a password");
      length = pw1.length();
      pw2 = JOptionPane.showInputDialog("Re-enter a password");
      if (!pw1.equals(pw2)){
        JOptionPane.showMessageDialog(null, "Password mismatch", "Error", JOptionPane.ERROR_MESSAGE);
      }
      else{
        output.println(pw1);
      }
      if (length<7){
        JOptionPane.showMessageDialog(null, "Your password must be at least 7 characters long", "Error", JOptionPane.ERROR_MESSAGE);
        pw2 = "";
      }
    }while(!pw1.equals(pw2));
  }
}

Why would you use a constructor to determine whether a String contains both chars and non-chars?

I don't know what to do, so I'm trying to figure something out by researching all my options at the moment. But thats why I posted here. Since Im lost on how to figure it out.

Like I said, the secret lies in looking through the APIs and playing around with the methods. If you have a specific question about one of the methods, post an SSCCE that demonstrates what you've tried, and we'll go from there.

If you're stuck on the algorithm, think about how you would do it "by hand". What directions would you give to somebody who has no idea how to tell whether a password has both characters and non-characters in it?

So far Ive been trying to use a loop. However now I cant figure out how to make sure that if it finds a number quit immedietly without showing the message that there needs to be a number, in addition to not showing the message until it finishes checking the whole password(aka input)

for (int count = 0; count < length; count++) {
        if (Character.isDigit(pw1.charAt(count))){
          count = length;
        }
        else{
          JOptionPane.showMessageDialog(null, "Your password must include a number", "Error", JOptionPane.ERROR_MESSAGE);
          count = length;
          pw2 = "";
        }
      }

Originally Posted by computercoder

So far Ive been trying to use a loop. However now I cant figure out how to make sure that if it finds a number quit immedietly without showing the message that there needs to be a number, in addition to not showing the message until it finishes checking the whole password(aka input)

Branching Statements (The Java™ Tutorials > Learning the Java Language > Language Basics)

But what happens if the user enters a password that is all digits? And don't you want to accept a password that includes both letters and punctuation, but not digits?

You could also check out Pattern (Java Platform SE 6)