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Chapter 10 – Arrays and ArrayLists 1
Array Basics
Array Declaration Array Creation
Array Element Initialization Array Default Values
Array length Property Partially Filled Arrays
Copying an Array
Searching an Array Sorting an Array
Selection Sort
Chapter 10 – Arrays and ArrayLists 2
TwoDimensional Arrays Arrays of Objects
The ArrayList Class
How to Create an ArrayList Object
Adding Elements to an ArrayList Object
How to Access an Element Within an ArrayList How to Update an ArrayList Object
Additional ArrayList Methods
Printing or Concatenating an ArrayList Storing Primitives in an ArrayList
ArrayList Example Using Anonymous Objects and the ForEach Loop
ArrayList Objects Versus Standard Arrays
Array Basics 3
A class stores a group of related data, and it stores the methods that operate on that data.
An array is a limited version of a class.
Like a class, an array also stores a group of related data, but an array does not store methods.
Another difference between an array and a class is that an array`s data must all be of the same type.
Here`s a picture of an array that holds a list of phone numbers. Each of the five boxes is called an array element and each box stores one phone number.
phoneList
8167412000 first phone number
2024561111
7852963232
8008675309
0035318842133 last phone number
Array Basics 4
A class uses dot notation to access one of its members.
On the other hand, an array uses square brackets around an index to access one of its elements.
The rightmost column shows how to access each of the 5 elements in the phoneList array.
Note that the index values start at 0 instead of 1 and the last index value is one less than the number of elements in the array.
index phoneList
0 8167412000 1 2024561111 2 7852963232 3 8008675309
4 0035318842133
how to access each element
phoneList[0] phoneList[1]
phoneList[2] 5 elements phoneList[3]
phoneList[4]
Array Basics 5
Here`s how you can change the first phone number to 2013434:
phoneList[0] = 2013434;
And here`s how you can print the second phone number:
System.out.println(phoneList[1]);
...
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