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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) 
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) 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;