Specifying the Public Interface of a Class

Behavior of bank account (abstraction):
    - deposit money
    - withdraw money
    - get balance

Methods of BankAccount class:
    - deposit
    - withdraw
    - getBalance

We want to support method calls such as the following:

harrysChecking.deposit(2000);
harrysChecking.withdraw(500);
System.out.println(harrysChecking.getBalance());

Method Definition

- access specifier (such as public)
- return type (such as String or void)
- method name (such as deposit)
- list of parameters (double amount for deposit)
- method body in { }

Examples:
public void deposit(double amount) { . . . }
public void withdraw(double amount) { . . . }
public double getBalance() { . . . }

Constructor Definition

• A constructor initializes the instance variables

• Constructor name = class name

• Constructor body is executed when new object is created

• Method Overload - you may have more than one constructor (same name, different number of parameters).

• Example: public BankAccount(double initialBalance) { balance = initialBalance;}

Class Definition