オ・ト・ナのカプセル化再入門 ref: http://qiita.com/eccyan/items/a14097b75e0cf6d924f3

file0.java

package shape;

// Subsystem
public Line extends Shape { 
  public void draw(Point from, Point to) { ... }
}

// Subsystem
public Circle extends Shape {
  public void draw(Point point) { ... }
}

file1.java

package widget;

// Facade
public AwesomeWindow {
  private Line line = new Line();
  private Circle circle = new Circle();

  public void draw() {
    Display display = Display.getInstance();
    line.draw(display.getCornerTopLeft(), display.getCornerTopRight()));
    line.draw(display.getCornerTopLeft(), display.getCornerBottomLeft()));
    line.draw(display.getCornerTopRight(), display.getCornerBottomRight()));
    line.draw(display.getCornerBottomRight(), display.getCornerBottomLeft()));

    circle.draw(display.getCenter());
  }
}

file2.java

package assembly;

// パッケージ内からのみアクセス許可
class Processor { ... }
class Memory { ... }
class Display { ... }

public class Phone {
  public static class Factory {
    public static Phone create(ProcessorType processorType, int memorySize) {
      return new Phone(new Processor(processorType), new Memory(memorySize));
      }
    }
  }

  private Processor processor;
  private Memory memory;
  private Display display;

  Phone(ProcessorType processortype, int memorySize) {
    processor = new Processor(processortype);
    memory = new Memory(memorySize);
    display = new Display();
  }

  public render() {
    processor.render(display, memory);
  }

  // Setter 等の状態変更はさせてはならない
  ...
}

file3.java

package person;

class Name { ... }
class Address { ... }
class Interest { ... }

public class Profile {
  public static class Factory {
    ...
  }

  private boolean requiredName;
  private Name name;
  private List<Interest> interests;
  private List<Address> addresses;

  // 興味が追加出来るか
  public boolean canAddInterest() {
    return interests.size() > 5;
  }

  // 名前を必須項目にするか
  public void setRequiredName(boolean required) {
    requiredName = required;
  }

  // プロフィールが完全か
  public boolean hasCompleted() {
    return (requiredName && name != null) && interests.size() > 0 && addresses.size() > 0;
  }

  public void addInterest(String interestText) {
    if (!canAddInterest()) { throw new Exception(); }
    interests.add(new Interest(interestText));
  }

  ...
}

file4.java

package zoo;

interface Animal {
  String getSound();
}

public class Animal {
  public static class Factory {
    ...
  }

  private List<Animal> animals;

  // クライアントにとって解りやすいインタフェースを提供する
  public void makeSounds() {
    for (Animal animal : animals) {
      System.out.println(animal.getSound())
    }
  }

  ...
}