4.30 Java4160: the toarray method, part 2

Revised: Fri Apr 08 13:14:35 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
  • Beginning with a quiz
    • And the answer is ...
    • Similar to previous program
    • A populated array
    • Display the array contents
    • A new LinkedList collection
    • Populating the LinkedList collection
    • Four buttons and two labels
    • The toolTipText property
    • JButton and JLabel
    • Making the objects distinguishable
    • Identifying the buttons and labels
    • Display the collection
    • Copy collection elements into an array
  • The toArray method
    • The essential difference
    • Type is not an issue for the simpler version
    • Size is not an issue for the simpler version
  • More-complex version presents some issues
    • The type issue
    • Two types of objects in this collection
    • The size issue
    • So, what did I do?
    • More information from Oracle
  • The output
    • Demonstrates same array was used
    • What if the array was too small?
    • Not difficult to demonstrate
    • Array as large as or larger than collection
    • Array smaller than the collection
  • Modify an object
    • Now for the caution
• 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 Collectionsframework in particular.

This module shows you how to use the more-complex version of the toArray method declared in the Collection interface. The module discusses issues regarding the type of the array and the types of the objects referred to by the elements in the collection. The module also discusses issues regarding the relative sizes of the array and the collection. Finally,the module reaffirms that you need to exercise caution when using the elements stored in the array, to avoid corrupting the state of the objects referred to by the elements in the collection.

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 ToArray02.
• Listing 2 . A populated array.
• Listing 3 . A new LinkedList collection.
• Listing 4 . The fillIt method.
• Listing 5 . Copy collection elements into an array.
• Listing 6 . Modify an object .