Accessing Instance Fields

• The deposit method of the BankAccount class can access the private instance field:
  public void deposit(double amount)
  {
     double newBalance = balance + amount;
     balance = newBalance;
  }
• Other methods cannot:
  public class BankRobber
  {
     public static void main(String[] args)
     {
       BankAccount momsSavings = new BankAccount(1000);
       . . .
       momsSavings.balance = -1000; // ERROR
     }
  }
• Encapsulation = Hiding data and providing access through methods