<META http-equiv="Content-Type" content="text/html; charset=UTF-8">

<title>Javanotes 9, Chapter 7 -- Arrays, ArrayLists, and Records</title>

<link type="text/css" rel="stylesheet" href="../javanotes.css">

<div class="page">

<div align="right">

[ <a href="s1.html">First Section</a> |

<a href="../c6/index.html">Previous Chapter</a> |

<a href="../c8/index.html">Next Chapter</a> |

<a href="../index.html">Main Index</a> ]

</small>

<div class="content">

<h3 class="chapter_title">Chapter 7</h3>

<h2 class="chapter_title">Arrays, ArrayLists, and Records</h2>

<hr class="break">

<span class="start"><big>C</big>omputers get a lot of their power</span> from working

with <span class="newword">data structures</span>. A data structure is an

organized collection of related data. An object is a data structure, combined

usually with some methods, but this

type of data structure&mdash;consisting of a fairly small number of named instance

variables&mdash;is just the beginning. In many cases, programmers build

complicated data structures by hand, by linking objects together. We'll look at

these custom-built data structures in <a href="../c9/index.html">Chapter&nbsp;9</a>. This

chapter looks at more basic data structures. There is one type of

data structure that is so important and so basic that it is built into every

programming language: the array.</p>

<p>You have already encountered arrays in <a href="../c3/s8.html">Section&nbsp;3.8</a>

and <a href="../c5/s1.html#OOP.1.4">Subsection&nbsp;5.1.4</a>. We continue the study of arrays in this chapter,

including some new details of their use and some additional array-processing

techniques. In particular, we will look at the important topic of algorithms for

searching and sorting an array in <a href="../c7/s5.html">Section&nbsp;7.5</a>.</p>

<p>An array has a fixed size that can't be changed after the array is created.

But in many cases, it is useful to have a data structure that can grow and shrink

as necessary. In <a href="../c7/s3.html">Section&nbsp;7.3</a>, we will look at a standard class,

<span class="classname">ArrayList</span>, that represents such a data structure.</p>

<p>An array is a numbered sequence of items, all of the same type. A <span class="newword">record</span>

is another kind of standard data structure. Like an array, a record consists of a sequence of items,

but in a record, the items are referred to by name instead of by number, and

the items can be of different types. Any object in Java can be thought of

as a record in this sense, but Java&nbsp;17 introduced records explicitly

into the language as a special kind of class with certain restrictions.

We will look at record classes in <a href="../c7/s4.html">Section&nbsp;7.4</a>.</p>

<hr class="break">

<h3>Contents of Chapter 7:</h3>

<ul class="contents">

<li>Section 1: <a href="s1.html">Array Details</a>

<li>Section 2: <a href="s2.html">Array Processing</a>

<li>Section 3: <a href="s3.html">ArrayList</a>

<li>Section 4: <a href="s4.html">Records</a>

<li>Section 5: <a href="s5.html">Searching and Sorting</a>

<li>Section 6: <a href="s6.html">Two-dimensional Arrays</a>

<a href="exercises.html">Programming Exercises</a>

<a href="quiz.html">Quiz on This Chapter</a>

<div align="right">

[ <a href="s1.html">First Section</a> |

<a href="../c6/index.html">Previous Chapter</a> |

<a href="../c8/index.html">Next Chapter</a> |

<a href="../index.html">Main Index</a> ]

</small>