(feat) Implement exercise section 4 - SavingsAccount

week23.java

@@ -88,6 +88,10 @@ class BankAccount {
         return balance;
     }
 
+    public void setBalance(double balance) {
+        this.balance = balance;
+    }
+
     public void deposit (double amount) {
         this.balance += amount;
     }
@@ -216,3 +220,69 @@ class DemoStudentLecturer {
         System.out.println(String.format("%s\t\t&\t\t%s", adrian, trefusis));
     }
 }
+
+class SavingsAccount extends BankAccount {
+    @Override
+    public String toString() {
+        return "SavingsAccount [interestRate=" + interestRate + "]";
+    }
+
+    private double interestRate;
+
+    /** Set up savings account for the thrifty
+     * @param person A {@link Person} object
+     * @param interestRate Expressed as %
+     */
+    public SavingsAccount(Person person, double interestRate) {
+        super(person);
+        this.interestRate = interestRate;
+    }
+
+    @Override
+    public void withdraw(double amount) {
+        if (amount <= this.getBalance()) {
+            this.setBalance(this.getBalance() - amount);
+        }
+    }
+
+    public void addInterest() {
+        this.setBalance(this.getBalance() + (this.getBalance() * (this.interestRate / 100)));
+    }
+}
+
+class DemoSavingsAccount {
+    public static void main(String[] args) {
+        Person hotblack = new Person();
+        hotblack.setName("Hotblack Desiato");
+
+        SavingsAccount savings1 = new SavingsAccount(hotblack, 6);
+        savings1.deposit(100.00);
+
+        System.out.println(String.format("%s plays a gig with DA and gets paid", hotblack));
+        System.out.println(String.format("Account:\n\t%s", savings1));
+        System.out.println(".".repeat(80));
+
+        System.out.println(
+                String.format("%s has a PGGB and tries to take out £200 to cover the cleanup expenses!", hotblack));
+        savings1.withdraw(200.00);
+        System.out.println(String.format("Account:\n\t%s", savings1));
+        System.out.println(String.format("Fortunately (?), his bank blocks the transaction."));
+        System.out.println(".".repeat(80));
+
+        System.out.println(String.format("After 1 year, %s's account accrues interest!", hotblack));
+        savings1.addInterest();
+        System.out.println(String.format("Account:\n\t%s", savings1));
+        System.out.println(String.format("%s wonders what it would be like after 1000 years...", hotblack));
+        System.out.println(".".repeat(80));
+
+        for (int i=0; i < 999; i++) {
+            savings1.addInterest();
+            if (i % 20 == 0) {
+                System.out.printf("%.2f\t", savings1.getBalance());
+            }
+        }
+        System.out.println(String.format("...finally, after 1000 years spent dead for tax purposes, %s checks his account", hotblack));
+        System.out.println(String.format("Account:\n\t%s", savings1));
+
+    }
+}