Gfrktyl

I have been working on this program a while trying to fix this problem, but with no success. So I ask for some assistance here. This java program gives the error:

Exception in thread "main" 

java.util.NoSuchElementException

at java.util.Scanner.throwFor(Unknown Source)

at java.util.Scanner.next(Unknown Source)

at NetworkandInternetSecurity.Login.main(Login.java:113)

Register.java

package Network;

import java.io.File;  

import java.io.FileNotFoundException;

import java.io.FileWriter;

import java.io.IOException;

import java.io.PrintWriter;

import java.nio.charset.Charset;

import java.security.MessageDigest;

import java.security.NoSuchAlgorithmException;

import java.util.ArrayList;

import java.util.Scanner;



public class Register {



static String hash(String str) {



String hashed = "";

try {



MessageDigest security = MessageDigest.getInstance("SHA-512");

security.update(str.getBytes(Charset.forName("UTF8")));



// message digest

byte bytes = security.digest();

StringBuffer buffer = new StringBuffer();



for (int i = 0; i < bytes.length; ++i) {



buffer.append(Integer.toHexString((bytes[i] & 0xFF) | 0x100)

.substring(1, 3));



}

hashed = buffer.toString();

} catch (NoSuchAlgorithmException e) {



e.printStackTrace();

}



return hashed;

}



// Main Method

public static void main(String args) throws FileNotFoundException, 

IOException {



// create file

FileWriter object = new FileWriter("database.txt", true);

File store = new File("database.txt");

Scanner sc1 = new Scanner(store);



// store usernames

ArrayList user_ar = new ArrayList();

ArrayList pass_ar = new ArrayList();

while(sc1.hasNext()) {

String user1 = sc1.next().trim();

String hash1 = sc1.next();

user_ar.add(user1);

pass_ar.add(hash1);

}



// register

Scanner sc = new Scanner(System.in);

System.out.println("Enter new user, Yes or No?");

String response = sc.next();

while (response.equals("Yes")) {



System.out.print("choose a username: ");

String user = sc.next();

while(user_ar.indexOf(user)!=-1) {

System.out.println("username already exists. Please try again:");

user = sc.next();

}

user_ar.add(user);

System.out.print("Choose a password: ");



 String pwd = sc.next();

String newHash = hash(pwd);



// write to file

FileWriter object1 = new FileWriter("database.txt", true);

PrintWriter writer = new PrintWriter(object1);

writer.write("rn");

writer.write(user);

writer.write("t");

writer.write(newHash);

writer.write("t"); // Assignment requires plaintext password to be stored

writer.write(pwd); // Assignment requires plaintext password to be stored

writer.close();



System.out.println("Do you want to create another user, Yes or No?");

response = sc.next();

}



System.out.println("Account created.");

}

}

Login.java

package Networtk;

import java.io.File;

import java.io.FileNotFoundException; 

import java.io.FileWriter;

import java.io.IOException;

import java.io.PrintWriter; 

import java.nio.charset.Charset; 

import java.security.MessageDigest; 

import java.security.NoSuchAlgorithmException;

import java.util.ArrayList;

import java.util.Scanner; 



public class Login {



static String hash(String str) {



String hashed = ""; 



try { 



MessageDigest security = MessageDigest.getInstance("SHA-512"); 

security.update(str.getBytes(Charset.forName("UTF8"))); 





   byte bytes = security.digest();

   StringBuffer buffer = new StringBuffer(); 





   for (int i = 0; i < bytes.length; ++i) {





  buffer.append(Integer.toHexString((bytes[i] & 0xFF) | 0x100)

   .substring(1, 3));



   }

   hashed = buffer.toString();

   } catch (NoSuchAlgorithmException e) { 



   e.printStackTrace(); 

   }



   return hashed;

   }





public static void main(String args) throws FileNotFoundException {



File store = new File("database.txt");

if (!store.exists()) { 



System.out.println(store + " not found, run the program first. ");



System.exit(0); 

}



ArrayList <String> user_ar = new ArrayList<String>(); 

ArrayList <String> pass_ar = new ArrayList<String>(); 



Scanner sc = new Scanner(store);



while(sc.hasNext()) {

String user = sc.next().trim();

String hash = sc.next().trim();

user_ar.add(user);

pass_ar.add(hash);

}



sc = new Scanner(System.in);



boolean done = false;

int attempts = 0;



while (!done) {



// ask user for username and password

System.out.print("Enter registered username: ");



String userName = sc.next();



System.out.print("Enter your password: ");



String pwdword = sc.next();



int index=user_ar.indexOf(userName);



if (index!=-1) {



if (hash(pwdword).equals(pass_ar.get(index))) {

done = true;



System.out.println("Login successful");

} else {

System.out.println("Incorrect password");

}

} else {

System.out.println("Login unsuccessful. You are not registered.");

}



attempts++; 

if (attempts == 3 && !done) {



System.out.println("You reached the max login attempts. Account locked..");



done = true;



}

}

}

}