JAVA PROBLEM

Here is the copied and pasted code so its easy to copy:

package coll.UserAccounts; public class BankAccount { /**  * Constructs a bank object with $0.0 funds and assigns the given User as the  * owner.  * @param owner  */ public BankAccount(User owner) { } /**  * Gets the total funds in the account.  * @return  */ public double getFunds() { return 0; } /**  * Deposits money into the account.  * @param deposit. The sum of money in $ to be deposited.  */ public void deposit(double deposit) { } /**  * Withdraws money from the account. Only the owner can withdraw funds.  * @param user. The user attempting to withdraw funds.  * @param withdrawal. The amount to be withdrawn.  * @throws UserException if anyone but the owner is attempting to withdraw fundss.  * @throws FundsException if there are insufficient funds in the account.  */ public void withdraw(User user, double withdrawal) throws UserException, FundsException { } } 

package coll.UserAccounts; public class FundsException extends Exception { } 

package coll.UserAccounts; /**  * Exists as a primitive front-end for the User and BankAccount classes.  */ public class GUI { /**  * Transfers money from one account to another. If the withdraw fails due to a  * UserException then print "Unauthorized access!" If the withdraw fails due to  * a FundsException then print "Insufficient funds!"  *   * @param user. The user that is attempting to execute the transfer.  * @param b1. The bank account that the funds are being transferred from.  * @param b2. The bank account that the funds are being transferred to.  * @param amount. The amount of money to be transferred in $.  */ public static void transfer(User user, BankAccount b1, BankAccount b2, double amount) { } } 

package coll.UserAccounts; public class User { /**  * Constructs a user with a given username and password. If a user is  * successfully constructed, their username is added to the list of usernames.  *   * @param username  * @param password  * @throws Exception.  * Throws a UserException if the username or password is invalid  * (use the below methods badUsername and badPassword to assist you  * with this).  */ public User(String username, String password) throws Exception { } /**  * Gets the username of the user.  *   * @return  */ public String getUsername() { return null; } /**  * Gets the password of the user.  *   * @return  */ public String getPassword() { return null; } /**  * Checks if a given username is invalid  *   * @param username  * @return true if the username already exist, false otherwise.  */ public static boolean badUsername(String username) { return false; } /**  * Checks if a given password is invalid.  *   * @param password  * @return true if the password is fewer than 8 characters long, false  * otherwise.  */ public static boolean badPassword(String password) { return false; } } 

package coll.UserAccounts; public class UserException extends Exception { } 

Requirements Your task is to develop a simple online banking system. There are: Two exceptions classes: UserException FundsException Two backend classes: User BankAccount One frontend class: GUI UserException and FundsException both subclass Exception, and Your task is to complete User, BankAccount, and GUI by using object-oriented programming, and exception throwing& handling. You will need to create a static ArrayList named usernames in the User class to maintain a list of usernames that have been are already implemented taken: static ArrayList usernames = new ArrayList(); Note that a try/catch must be used in the GUl class to gracefully handle potential exceptions. You should not rethrow exceptions in the GUI Requirements Your task is to develop a simple online banking system. There are: Two exceptions classes: UserException FundsException Two backend classes: User BankAccount One frontend class: GUI UserException and FundsException both subclass Exception, and Your task is to complete User, BankAccount, and GUI by using object-oriented programming, and exception throwing& handling. You will need to create a static ArrayList named usernames in the User class to maintain a list of usernames that have been are already implemented taken: static ArrayList usernames = new ArrayList(); Note that a try/catch must be used in the GUl class to gracefully handle potential exceptions. You should not rethrow exceptions in the GUI