Phase III

-   Added:
    -   AccountInterface
    -   CheckingAccount
    -   SavingsAccount
-   Converted Account to abstract class
-   All instance variables are validated via exception handling

src/bankAcctApp/SavingsAccount.java

@@ -0,0 +1,41 @@
+/* Phase III */
+
+package bankAcctApp;
+
+// Class representing savings accounts
+public class SavingsAccount extends Account {
+
+    // Overridden method for withdrawals in savings accounts
+    @Override
+    public void withdrawal(double amount) {
+        if (getBalance() >= amount + getSvcFee()) { // Ensure sufficient balance
+            setBalance(getBalance() - amount - getSvcFee()); // Deduct amount and service fee
+        } else {
+            throw new IllegalArgumentException("Insufficient funds for withdrawal. Savings accounts cannot overdraft.");
+        }
+    }
+
+    // Overridden method for deposits in savings accounts
+    @Override
+    public void deposit(double amount) {
+        setBalance(getBalance() + amount - getSvcFee()); // Add amount and deduct service fee
+    }
+
+    // Overridden method for applying accrued interest in savings accounts
+    @Override
+    public double applyAccruedInterest(String transactionDate) {
+        if (getBalance() <= 0) { // Ensure balance is positive for interest accrual
+            throw new IllegalArgumentException("The account has an insufficient balance for interest to apply.");
+        }
+        double interest = getBalance() * (getInterestRate() / 100); // Calculate interest
+        setBalance(getBalance() + interest); // Add interest to the balance
+        logTransaction(transactionDate, "INT", interest); // Log the interest transaction
+        return interest;
+    }
+
+    // Implementation of balance() method from AccountInterface
+    @Override
+    public double balance() {
+        return getBalance(); // Return the current balance
+    }
+}