CODEWITHSUNDEEP
javastringif-statement
Tia
Tia

Reputation: 1230

Check for a specific set of characters(of a password) in a string

I have to write a program which checks a password.

The program is working only for the if part but not for the else.
That is when I input bolt, it displays the correct message.
But when I enter something other than bolt, it does not display 'The password is invalid'.
I have been told to test for all four characters that is to use char.At.

import java.util.Scanner;

public class MyClass {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.println("Please enter your 4-character password:");
        String password = input.next();

        for (int i = 0; i < password.length(); i++) {
            if (password.charAt(i) == 'B' || password.charAt(i) == 'b')
                if (password.charAt(i + 1) == 'O'
                        || password.charAt(i + 1) == 'o')
                    if (password.charAt(i + 2) == 'L'
                            || password.charAt(i + 2) == 'l')
                        if (password.charAt(i + 3) == 'T'
                                || password.charAt(i + 3) == 't') {

                            System.out.println("The password is valid");
                        }
                        else {
                            System.out.println("The password is invalid!");

                        }
        }
}

Upvotes: 0

Views: 1344

Answers (5)

Daman Arora
Daman Arora

Reputation: 87

What you are doing is not making much sense. You should probably use a character array an then check sequentially. Another small thing is that the else block is associated with the last if statement. Where it should be attached to the first if. This is one place where you need to use braces intelligently.

Upvotes: 0

Codebender
Codebender

Reputation: 14471

For your updated question:

String password = input.next().toLowerCase();
String correctPassword = "bolt";

if (password.length() != correctPassword.length()) {
    System.out.println("Not valid");
    return;
}

for (int i = 0; i < correctPassword.length(); i++) {
    if (password.charAt(i) != correctPassword.charAt(i)) {
        System.out.println("Not valid");
        return;
    }
}
System.out.println("Valid");

In your code there are two problems, 1. Your for loop doesn't serve any purpose because you have checked the whole password in the first iteration itself. Your second iteration would cause IndexOutOfBoundsException.

  1. You didnt see the invalid password message because, your else condition is applied only to the innermost if (which checks for the char "T" or "t").
    So, if the provided password starts with "BOL" but last char is different like "BOLA" or "BOLB", then you would see the invalid message. But if the first three char fail, then it wont execute the else.

Hope this helps..

Upvotes: 1

Marcel St&#246;r
Marcel St&#246;r

Reputation: 23535

Why don't you just check for String equality directly?

String password= input.next();
if("bolt".equals(password))) {
  System.out.println("Valid password");
} else {
  System.out.println("InValid password");
}

Or use equalsIgnoreCase() if you'd also consider BOLT or Bolt valid.

If you need to implement this without equals you could use something like this:

if (password != null && 
    password.length() == 4 && 
    (password.charAt(0) == 'B' || password.charAt(0) == 'b') && 
    ...) {
  System.out.println("Valid password");
} else {
  System.out.println("InValid password");
}

Upvotes: 2

Akash Rajbanshi
Akash Rajbanshi

Reputation: 1593

It would be more readable to check using equalsIgnoreCase():

String password= input.next();
if(password.equalsIgnoreCase("bolt"){
   System.out.println("The password is valid");
}
else{
   System.out.println("The password is invalid!");
}

Upvotes: 2

Avinash Raj
Avinash Raj

Reputation: 174716

I'did use string.matches function which accepts regex as argument. (?i) helps to do a case-insensitive match.

if(string.matches("(?i)bolt")) 
{
System.out.println("Valid password");
}
else {System.out.println("InValid password");}

Upvotes: 1

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