Unit 6: Array

Question 1

an array is __.

Answer 1

a data structure used to implement a collection (list) of primitive or object reference data

Question 2

an element is __.

Answer 2

a single value in the array

Question 3

an array’s length ___.

Answer 3

cannot be changed after it’s been created

Question 4

initializing an array:

Answer 4

dataType [] arrayName = new dataType[element 3]

ex. int [] array = new int[5];

NOTE: there must be a nonnegative integer or 0 in the [ ]

Question 5

when just initializing an array’s num of elements, each element is __.

(name for each of 4 data types)

Answer 5

0 for int, 0.0 for double, false for boolean, null for String

Question 6

how to set array element to value:

Answer 6

array[index] = value

ex. array[0] = 5;

Question 7

how to initialize array with object elements:

how to set object values:

Answer 7

className [] arrayName; OR
className[] arrayName = new arrayName [num of elements];

arrayName[index] = new className(attribute);

Question 8

how to make array with known values:

Answer 8

dataType [] arrayName = {element1, element2, …};

NOTICE curly braces

Question 9

only use [] after array name when___.

Answer 9

accessing a certain element, not initializing the entire array

Question 10

for: each loop structure:

Answer 10

for( dateType variable: array)
{
}

Question 11

how to print out all elements of an array with for: each loop

Answer 11

for (dataType variable: array){
System.out.prtinln(variable);
}

NOTE: variable is a copy of what’s in the array, so don’t need to put index of variable