Introduction to One Dimensional Arrays

Enhanced For / For Each Loop

A special for loop for going through all the items in a data set.

Index

A location in an array, where a value is stored.

1D Array Creation (Size Known)

type[] name = new type[size];

1D Array Creation (Size and Values Known)

type[] name = {value,value,value,value,..., value};

Replacing a 1D Array

name = new type[]{value,value,value,value,..., value};

Getting the Size of a 1D Array

name.length

Accessing Value at an Index

name[index]

Changing Values in an Array

name[index] = value;

Array

A structure for storing multiple values in a single variable.

Element

A single value stored by an array.

Printing All Values in an Array

for(int x = 0; x < name.length; x++) System.out.println(name[x]);

For Each Loop Format

for(typeOfDataInArray variableName: arrayName) // code using the variableName

Turning a String into a char Array

char[] arrayName = StringName.toCharArray();

Null Pointer Exception

Occurs if an array variable stores null and you try to access or change an element.

Arrays Class

The Arrays class has methods to perform operations on arrays.

Arrays Class Import Statement

import java.util.Arrays;

Arrays Class Method: sort

sort(arrayName) - Sorts the given array.

Arrays Class Method: toString

toString(arrayName) - Prints the given 1D array.

Arrays Class Method: deepToString

deepToString(arrayName) - Prints the given 2D array.

First Index of an Array

The first index in an array is at index 0.

Last Index of an Array

The last index is (number of elements stored) - 1.

Automatic Initialization of int and double Arrays

Values will be initialized to 0 automatically.

Automatic Initialization of boolean Arrays

Values will be initialized to false automatically.

Automatic Initialization of Object Arrays

Values will be initialized to null automatically.