ch_5.scala

// 1
class Counter {
  private var value: Int = 0

  def increment() { value += 1 }
}


// 2
class BankAccount {
  private var value: Double = 0.0

  def deposit(d: Double) = { value = value + d }

  def withdraw(d: Double) = { value = value - d }

  def balance = value
}


// 3
class Time(val hours: Int, val minutes: Int) {
  def before(other: Time): Boolean = other match {
    case other if (hours == other.hours && minutes < other.minutes) => true
    case other if (hours < other.hours) => true
    case _ => false
  }
}


// 4
class Time(val hours: Int, val minutes: Int) {
  private val time_since_midnight = hours * 60 + minutes

  def before(other: Time): Boolean = {
    if (time_since_midnight < other.time_since_midnight) true else false
  }
}


// 5
class Student {
  @reflect.BeanProperty var name: String = _
  @reflect.BeanProperty var id: Long = _
}

/*
  $ javap Student
  Compiled from "student.scala"
  public class Student extends java.lang.Object{
      public java.lang.String name();
      public void name_$eq(java.lang.String);
      public void setName(java.lang.String);
      public long id();
      public void id_$eq(long);
      public void setId(long);
      public java.lang.String getName();
      public long getId();
      public Student();
  }

  Yes, you can call the JavaBeans getters and setters in Scala.
  Probably not, if both functions do the same thing it would seem better to have one uniform way to access a class
*/


// 6
class Person(a: Int) {
  val age: Int = if (a < 0) 0 else a
}

// 7
class Person(var fullName: String) {
  val firstName: String = fullName.split(" ").head
  val lastName: String = fullName.split(" ").last
}

// val so it's consistent with the other properties of the class


// 8
class Car(var manufacturer: String, var model: String, var model_year: Int, var license_plate: String) {
  def this(manufacturer: String, model: String) {
    this(manufacturer, model, -1, "")
  }

  def this(manufacturer: String, model: String, model_year: Int) {
    this(manufacturer, model, model_year, "")
  }

  def this(manufacturer: String, model: String, license_plate: String) {
    this(manufacturer, model, -1, license_plate)
  }
}

// 9
// Java
public static void main(String[] args) {
  Car test = new Car("VW", "Jetta", "HA HA");
  System.out.println(test.getModelYear());
  System.out.println(test.getLicensePlate());
  // -1
  // HA HA
}

public class Car {
  private String manufacturer;
  private String model;
  private int modelYear;
  private String licensePlate;

  public String getManufacturer() { return manufacturer; }
  public String getModel() { return model; }
  public int getModelYear() { return modelYear; }
  public String getLicensePlate() { return licensePlate; }

  public Car(String manufacturer, String model) {
    this(manufacturer, model, -1, "");
  }

  public Car(String manufacturer, String model, int modelYear) {
    this(manufacturer, model, modelYear, "");
  }

  public Car(String manufacturer, String model, String licensePlate) {
    this(manufacturer, model, -1, licensePlate);
  }

  public Car(String manu, String mod, int year, String license) {
    manufacturer = manu;
    model = mod;
    modelYear = year;
    licensePlate = license;
  }
}


// 10
class Employee(val name: String, var salary: Double) {
  def this() { this("John Q. Public", 0.0) }
}

class Employee(n: String = "John Q. Public", s: Double = 0.0) {
  val name = n
  var salary = s
}

/*
  the explicit form seems nicer, mostly because it skips the auxiliary constructor
  it's method signature is pretty verbose though...
*/