Error with my brute force password generator(Java)

Question

This is an assignment for class, basically make a method that can "guess" the password then send it to another class which will de-crypt a file. I have the hard part done.

import sussex.edu.Cryptography;

public class Final {

    public static void main(String[] args) throws Exception{
        //decrypter();
        Cryptography crypto = new Cryptography();

        String encrypted = "SourceFile_encrypted.txt";
        String decrypted = "SourceFile_decrypted.txt";
        String password = new String();

        crypto.setPassword(password);
        if(crypto.isPasswordValid()){
            System.out.println("Found password:" + password);
            crypto.decryptFile(encrypted, decrypted);
        }
        else{
            //Keep trying...
        }
    }
    public static String decrypter(){
        char array[] = new char[5];
        Cryptography crypto = new Cryptography();
        String password = new String();

        for (char c0 = 'A'; c0 <= 'Z'; c0++) {
            array[0] = c0;
            for (char c1 = 'A'; c1 <= 'Z'; c1++) {
                array[1] = c1;
                for (char c2 = 'A'; c2 <= 'Z'; c2++) {
                    array[2] = c2;
                    for (char c3 = 'A'; c3 <= 'Z'; c3++) {
                        array[3] = c3;
                        for (char c4 = 'A'; c4 <= 'Z'; c4++){
                            array[4] = c4;
                            String s = new String(array);
                            password = s;
                            System.out.println(password);
                            crypto.setPassword(password);
                            if(crypto.isPasswordValid()){
                                break;
                            }
                        }
                    }
                }
            }
        }
        return password;
    }
}

It iterates through all possible passwords, and goes past the actual password,(OLLEH) and does nothing. When I manually enter the password into the first crypto.setPassword(password); It works just fine. when I enter it, it looks like crypto.setPassword("OLLEH"); but if I manually enter "OLLEH" into the crypto.setPassword(password); inside the nested for loop it doesn't work. So my error is in there, i just can't see it.

Answer 1

Probably your isPasswordValid() method is comparing Strings with == instead of equals().

That could explain why this comparison returns true when it's against "OLLEH", but false when it's against a String with the same value, but created using new.

Try substituting password = s; by password = s.intern ();