# L11 - Designing Exception Types Lab

In this lab, we'll create our own exception class for the `BankAccount` class to handle the case where a customer tries to withdraw more money than they have in their account.

1.	If you haven't already done so, complete the L06 Bank Account lab.
2.	Create an `InsufficientFunds` exception class that consists of the following statements: 
```
public class InsufficientFunds extends RuntimeException { 
  public InsufficientFunds() { } 
  public InsufficientFunds(String msg) { 
    super(msg); //use superclass RuntimeException constructor 
  } 
}
```
3.	Modify the withdraw method in the `BankAccount` class to compare the amount to the balance and throw an `InsufficientFunds` exception if there isn't enough money: 
```
public void withdraw(double amount) { 
  if (amount <= balance) balance -= amount; 
  else { 
    InsufficientFunds myEx;
  
    myEx = new InsufficientFunds("Amount exceeds balance"); 
    throw myEx; 
  } 
}
```
4.	Modify the `BankAccountTest` program so that it handles an `InsufficientFunds` exception: 
```
... 
else if (menuChoice.equalsIgnoreCase("W")) {

  try {
    System.out.print("Enter amount: "); 
    String answer = myScanner.nextLine(); 
    amount = Double.parseDouble(answer);
    myChecking.withdraw(amount); 
  }
  catch (InsufficientFunds myEx) { 
    System.out.println(myEx.getMessage()); 
    System.out.println("Transaction aborted!"); 
  } 
} ...
```
5.	Execute the `BankAccountTest` program using values that does not and does trigger the withdraw exception. 

##### Sample Dialog 
```
Enter initial checking account balance: 500 
D - Deposit into checking 
W - Withdraw from checking 
P - End of month processing
S - Show account balance
E - Exit the program 
>W
Enter amount: 100
>S 
Checking balance: 400.0
>W
Enter amount: 1000
Amount exceeds balance Transaction aborted!
>e 
Goodbye! 
```