Coffee example using decorators : Decorator Pattern « Design Pattern « Java Tutorial

1. Java Tutorial
2. Design Pattern
3. Decorator Pattern

interface Countable {
  String getName();

  float getCount();
}

class Book implements Countable {
  public String getName() {
    return "Book";
  }

  public float getCount() {
    return 0;
  }
}

abstract class Number implements Countable {
  protected Countable component;

  Number(Countable component) {
    this.component = component;
  }

  public float getCount() {
    return component.getCount();
  }

  public abstract String getName();
}

class Integer extends Number {
  private float value = 0.75f;

  private String description = " integer";

  public Integer(Countable component) {
    super(component);
  }

  public float getCount() {
    return component.getCount() + value;
  }

  public String getName() {
    return component.getName() + description;
  }
}

class Float extends Number {

  private String description = " float";

  public Float(Countable component) {
    super(component);
  }

  public String getName() {
    return component.getName() + description;

  }
}

class Double extends Number {
  private float value = 0.25f;

  private String description = " double";

  public Double(Countable component) {
    super(component);
  }

  public float getCount() {
    return component.getCount() + value;
  }

  public String getName() {
    return component.getName() + description;
  }
}

class Decimal extends Number {
  private float value = 0.25f;

  private String description = " decimal";

  public Decimal(Countable component) {
    super(component);
  }

  public float getCount() {
    return component.getCount() + value;
  }

  public String getName() {
    return component.getName() + description;
  }
}

class Positive extends Number {
  private float cost = 0.25f;

  private String description = " positive";

  public Positive(Countable component) {
    super(component);
  }

  public float getCount() {
    return component.getCount() + cost;
  }

  public String getName() {
    return component.getName() + description;
  }
}

class Negative extends Number {

  private float value = -0.25f;

  private String description = " negative";

  public Negative(Countable component) {
    super(component);
  }

  public float getCount() {
    return component.getCount() + value;
  }

  public String getName() {
    return component.getName() + description;
  }

}

public class NumberCountableDemo {
  public static void main(String[] args) {
    Countable cappuccino = new Integer(new Double(new Book()));
    System.out.println(cappuccino.getName().trim() + ": $" + cappuccino.getCount());
    Countable cafeMocha = new Integer(new Decimal(new Negative(new Positive(new Float(
        new Book())))));
    System.out.println(cafeMocha.getName().trim() + ": $" + cafeMocha.getCount());
  }
}