Arrays

Terminology

Array
A homogeneous collection of data referred to by a single name and a subscript.
In Java, an array is a reference type composed of elements of either primitive types or reference types.
Subscript (index)
The offset of an element of an array. The first element is subscript 0.
Element
A single member of the array collection.
ArrayIndexOutOfBoundsException
An exception (or run-time error) caused by trying to access an array element that does not exist.  For example trying to access myArray[6] when there are only 6 elements in the array.
Initializer List
A mechanism for instantiating an array using a list of values to initialize the elements.
Arrays - Arrays.ppt
  1. Motivation: StupidAverage.java, Average.java
  2. What are they? Collection of "cells" or containers.
  3. How are they defined? Declaration, instantiation, initializer list.
  4. How are they reference? Subscripted notation - See ArrayDemo1.java
  5. Loop processing - See ArrayDemo2.java
  6. Array processing errors are similar to loop processing. InvalidSubscript.java
  7. One solution - Use the .length attribute of arrays. InvalidSubscriptFixed.java
  8. Initializer lists. ArrayInitialization.java
  9. Inputting number of elements. DisplayTestScores.java
  10. Passing individual elements. PassElements.java

Things to remember about arrays:

Feature Syntax Example
Declaration data-type [] variable-name; int [] gradeArray;
Card [] deck;
Declaration
(alternative)		 data-type variable-name[]; int gradeArray [];
Card deck [];
Initializer list data-type [] list = { value, value, ... value} String [] names = { "bob", "ann", "amy", "sue", "sam"};
Instantiation new data-type[int-value] intArray = new int [25];
deck = new Card [cardCount];
Instantiation and initialization new data-type[] { value, value, ... value } names = new String [] { "bob", "ann", "sue", "sam" }; return new int [] {0};
Referring to the
array as a whole		 var-name return deck;
intArray = grades;

array2.equals(array1);
(What do you think this does compares?)

arrLength = names.length;
Specialized Arrays methods java.util.Arrays.fill(grades, 100);
java.util.Arrays.equals(section1, section2);
java.util.Arrays.sort(names);
java.util.Arrays.toString(names)
Referring to array elements var-name[int-value] return deck[0];
intArray[ii] = grades[jj];
rank = deck[ii].getRank();
while (intArray[ii] == 5)