Anatomy of a Class Practice Test

Considering the Java class example below, which access modifier would you use for owner to ensure encapsulation?

public class BankAccount {

  // Fields represent state

  private String owner;

  private double balance;

  public BankAccount(String owner, double startingBalance) {

    this.owner = owner;

    balance = startingBalance;

  }

  public String getOwner() { return owner; }

}

// Encapsulation: hide fields, expose methods.

// Inheritance: subclasses can extend BankAccount.

// Polymorphism: overridden methods can change behavior.

Based on the class structure presented above, which modifier best fits owner?

Considering the Java class example below, how does inheritance benefit the class structure?

public class Animal {

  private String name;

  public Animal(String name) {

    this.name = name;

  }

  public String getName() { return name; }

  public void speak() {

    System.out.println("...");

  }

}

public class Dog extends Animal {

  public Dog(String name) { super(name); }

  @Override

  public void speak() {

    System.out.println("Woof");

  }

}

// Encapsulation: name is private and accessed via getName().

// Inheritance: Dog reuses Animal code.

// Polymorphism: speak() can vary by subclass.

Based on the class structure presented above, how does inheritance benefit this design?