An Introduction to Inheritance

• Inheritance: extend classes by adding methods and fields
• Example: Savings account = bank account with interest

  class SavingsAccount extends BankAccount
  {
     new methods
     new instance fields
  }

• SavingsAccount automatically inherits all methods and instance fields of BankAccount

  SavingsAccount collegeFund = new SavingsAccount(10);
  // Savings account with 10% interest
  collegeFund.deposit(500);
  // OK to use BankAccount method with SavingsAccount object

• Extended class = superclass (BankAccount), extending class = subclass (Savings)
• Inheriting from class ≠ implementing interface: subclass inherits behavior and state
• One advantage of inheritance is code reuse