株式会社エス・スリー・フォー

C++/C#/VB.NETによる リファクタリング – リファクタリング後(Java)

Movie.java

// Movie.java

public class Movie {

  public static final int CHILDRENS = 2;
  public static final int REGULAR = 0;
  public static final int NEW_RELEASE = 1;

  private String _title;
  private Price  _price;

  public Movie(String title, int priceCode) {
    _title = title;
    setPriceCode(priceCode);
  }

  public int getPriceCode() {
    return _price.getPriceCode();
  }

  public void setPriceCode(int arg) {
    switch ( arg ) {
    case REGULAR :
      _price = new RegularPrice();
      break;
    case CHILDRENS :
      _price = new ChildrensPrice();
      break;
    case NEW_RELEASE :
      _price = new NewReleasePrice();
      break;
    default:
      throw new IllegalArgumentException("不正な料金コード");
    }
  }

  public String getTitle() {
    return _title;
  }

  public double getCharge(int daysRented) {
    return _price.getCharge(daysRented);
  }

  public int getFrequendRenterPoints(int daysRented) {
    return _price.getFrequentRenterPoints(daysRented);
  }

}

Rental.java

// Rental.java

public class Rental {

  private Movie _movie;
  private int _daysRented;

  public Rental(Movie movie, int daysRented) {
    _movie = movie;
    _daysRented = daysRented;
  }

  public int getDaysRented() {
    return _daysRented;
  }

  public Movie getMovie() {
    return _movie;
  }

  public double getCharge() {
    return _movie.getCharge(_daysRented);
  }

  public int getFrequentRenterPoints() {
    return _movie.getFrequendRenterPoints(_daysRented);
  }

}

Customer.java

// Customer.java

import java.util.*;

public class Customer {

  private String _name;
  private Vector _rentals = new Vector();

  public Customer(String name) {
    _name = name;
  }

  public void addRental(Rental arg) {
    _rentals.addElement(arg);
  }

  public String getName() {
    return _name;
  }

  public String statement() {
    Enumeration rentals = _rentals.elements();
    String result = "Rental Record for " + getName() + "\n";
    while ( rentals.hasMoreElements() ) {
      Rental each = (Rental)rentals.nextElement();
      // この貸し出しに対する数値の表示
      result += "\t" + each.getMovie().getTitle() + "\t" +
                String.valueOf(each.getCharge())+ "\n";
    }
    // フッタ部分の追加
    result += "Amount owed is " + String.valueOf(getTotalCharge()) + "\n";
    result += "You earned " + String.valueOf(getTotalFrequentRenterPoints()) +
              " frequent renter points";
    return result;
  }

  double getTotalCharge() {
    double result = 0;
    Enumeration rentals = _rentals.elements();
    while ( rentals.hasMoreElements() ) {
      Rental each = (Rental)rentals.nextElement();
      result += each.getCharge();
    }
    return result;
  }

  double getTotalFrequentRenterPoints() {
    int result = 0;
    Enumeration rentals = _rentals.elements();
    while ( rentals.hasMoreElements() ) {
      Rental each = (Rental)rentals.nextElement();
      result += each.getFrequentRenterPoints();
    }
    return result;
  }

}

Price.java

// Price.java

public abstract class Price {

  abstract public int getPriceCode();
  abstract public double getCharge(int daysRented);
  public int getFrequentRenterPoints(int daysRented) {
    return 1;
  }
}

class ChildrensPrice extends Price {

  public int getPriceCode() {
    return Movie.CHILDRENS;
  }

  public double getCharge(int daysRented) {
    double result = 1.5;
    if ( daysRented > 3 )
      result += (daysRented -3) * 1.5;
    return result;
  }

}

class NewReleasePrice extends Price {

  public int getPriceCode() {
    return Movie.NEW_RELEASE;
  }

  public double getCharge(int daysRented) {
    return daysRented * 3;
  }

  public int getFrequentRenterPoints(int daysRented) {
    return ( daysRented > 1 ) ? 2 : 1;
  }

}

class RegularPrice extends Price {

  public int getPriceCode() {
    return Movie.REGULAR;
  }

  public double getCharge(int daysRented) {
    double result = 2;
    if ( daysRented > 2 )
      result += (daysRented -2) * 1.5;
    return result;
  }

}