4.8 Java4050: core collection interfaces

Revised: Wed Apr 06 08:39:26 CDT 2016

This page is included in the following Books:

• ITSE 2321 - Object-Oriented Programming (Java)
• Object-Oriented Programming (OOP) with Java

Table of contents

• Preface
• Viewing tip
• Listings
• Preview
• Generics
• Discussion and sample code
  • Illustration of core collection interfaces
    • Multiple list implementations
    • TreeSet and ArrayList
    • Behavior is different but appropriate
  • The fillIt method
  • Create and populate a TreeSet object
    • Display the collection's contents
    • TreeSet object is type SortedSet
  • Create and populate an ArrayList object
    • Display the collection's contents
  • The important point
    • No duplicate elements in ascending order
    • Duplicates allowed with no sorting
  • Structure of the core interfaces
  • A Map is not a true Collection
  • Some operations are optional
    • Support for optional operations
    • Optional Collection operations
    • Optional Map operations
    • Many methods are not optional
• Run the program
• Summary
• What's next?
• Miscellaneous

Preface

This module is one of a series of modules designed to teach you about Object-Oriented Programming(OOP) in general and the Java Collections framework in particular.

The Java Collections Framework defines eight core interfaces, in two distinct trees. You will learn about the inheritance structure and the purpose of those interfaces.You will also learn how the interfaces declare polymorphic methods that apply to implementations of the interfaces, and you will learn about the optional methods of the Collection and Map interfaces.

In addition to studying these modules, I strongly recommend that you study the Collections Trail in Oracle's Java Tutorials . The modules in this collection are intended to supplement and not to replace those tutorials.

Viewing tip

I recommend that you open another copy of this module in a separate browser window and use the following links to easily find and view the listings while you are reading about them.

Listings

• Listing 1 . The program named Ap401.
• Listing 2 . The Populator class.
• Listing 3 . Create and populate a TreeSet object.
• Listing 4 . Create and populate an ArrayList object.

Preview

In earlier modules, you learned that at least three things are included in a collections framework:

• interfaces
• implementations
• algorithms

Earlier modules provided a general discussion of the purpose of the interfaces, implementations, and algorithms in the Collections Framework . This module takes that discussion further and illustrates the use of the core collection interfaces.

The Java Collections Framework defines eight core interfaces, in two distinct trees. You will learn the names and the inheritance structure of thoseinterfaces. You will also learn about the purpose of some of those interfaces. You will seehow the interfaces declare polymorphic methods that apply to implementations of the interfaces, and you will learn about the optional methods of the Collection interface.