Ex.1
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(The Account class) 

Design a class named Account that contains:

- A private int data field named id for the account (default 0 ).
- A private double data field named balance for the account (default 0 ).
- A private double data field named annualInterestRate that stores the 
current interest rate (default 0 ). Assume all accounts have the same interest rate.
- A private String data field named dateCreated that stores the date when the
account was created.
- A default constructor that creates a default account.
- A constructor that creates an account with the specified id and initial balance.
- The accessor and mutator methods for id , balance , and annualInterestRate.
- The accessor method for dateCreated.
- A method named getMonthlyInterestRate() that returns the monthly
interest rate.
- A method named getMonthlyInterest() that returns the monthly interest.
- A method named withdraw that withdraws a specified amount from the
account.
- A method named deposit that deposits a specified amount to the account.

Hints:
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The method getMonthlyInterest() is to return monthly interest, not the interest rate.
Monthly interest is balance * monthlyInterestRate. The monthlyInterestRate
is annualInterestRate / 12. Note that annualInterestRate is a percentage,
e.g., like 4.5%. You need to divide it by 100.

Write a test program that creates an Account object with an account ID of 1122,
a balance of $20,000, and an annual interest rate of 4.5%. Use the withdraw
method to withdraw $2,500, use the deposit method to deposit $3,000, and print
the balance, the monthly interest, and the date when this account was created.


Ex.2 
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(Game: ATM machine)

Use the Account class created in Ex.1 to simulate an ATM machine. 
Create ten Accounts in an array with id 0 , 1 , . . . , 9 , and initial balance $100. 
The system prompts the user to enter an id. If the id is entered incorrectly, ask the user to enter 
a correct id. Once an id is accepted, the main menu is displayed as shown in the sample run. You can
enter a choice 1 for viewing the current balance, 2 for withdrawing money, 3 for
depositing money, and 4 for exiting the main menu. Once you exit, the system
will prompt for an id again. Thus, once the system starts, it will not stop.

Enter an id: 4
Main menu
1: check balance
2: withdraw
3: deposit
4: exit
Enter a choice: 1
The balance is 100.0

Main menu
1: check balance
2: withdraw
3: deposit
4: exit
Enter a choice: 2
Enter an amount to withdraw: 3

Main menu
1: check balance
2: withdraw
3: deposit
4: exit
Enter a choice: 1
The balance is 97.0

Main menu
1: check balance
2: withdraw
3: deposit
4: exit
Enter a choice: 3
Enter an amount to deposit: 10

Main menu
1: check balance
2: withdraw
3: deposit
4: exit
Enter a choice: 1
The balance is 107.0

Main menu
1: check balance
2: withdraw
3: deposit
4: exit
Enter a choice: 4
Enter an id: