• 2.13.1 Introduction
• 2.13.2 Package Naming
• 2.13.3 Package Access
• 2.13.4 Package Contents
• 2.13.5 Examples

2.13 Packages

2.13.1 Introduction

• Packages have members that are related classes, interfaces, and subpackages.
• Packages are useful for several reasons:
• Packages create a grouping for related interfaces and classes.
• Interfaces and classes in a package can use popular public names that make sense in one context but might conflict with the same name in another package.
• Packages can have types and members that are available only within the package.

2.13.2 Package Naming

• A package name should be unique.A good way to ensure unique package names is to use an Internet domain name (reversed):

      package COM.missiondata.utils;
  

2.13.3 Package Access

• A public class or interface is accessible to code outside that package.
• Types that are not public have package scope; they are available to all other code in the same package, but are hidden outside the package and even from code in nested packages.
• Package scope is the default if public/protected/private are not declared.

2.13.4 Package Contents

• Contain functionally-related classes and interfaces.
• Classes in a package can freely access each other's non-private members.
• Should provide logical groupings for programmers looking for useful interfaces and classes.
• Packages can be nested inside other packages.

2.13.5 Examples

• The Model/View/Controller paradigm can help illustrate a good way of packaging MVC-related classes for a fictitional Pizza Store project:

      com.alspizzastore.model.Pizza
      com.alspizzastore.model.Topping
  
      com.alspizzastore.view.OrderEntryScreen
      com.alspizzastore.view.ReceiptView
  
      com.alspizzastore.controller.ReceiptController
      com.alspizzastore.controller.PricingController
  

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