Lec 8: Arrays

Question 1

Syntax for declaring an array

Answer 1

datatype[] arrayRefVar;

Question 2

Syntax for declaring an array of a specific size

Answer 2

dataType[] arrayRefVar = new dataType[arraySize];

ex: double[] myList = new double[10];

Question 3

Syntax for getting the length of an array

Answer 3

array.length

Question 4

What is the default value of a bool if not preset

Answer 4

false

Question 5

what is the default value of a char if not preset

Answer 5

‘\u0000’

it is an invisible character

Question 6

syntax for creating an array with specific double elements

Answer 6

double[] myList = new double[4]
myList[0] = 1.9;
myList[1] = 2.1;

or
double[] myList = {1.9, 2.9, 3.4, 3.5};

Question 7

What is the syntax for a foreach loop that prints all the elements in an array of double values

Answer 7

for (double value : myList){
System.out.println(value);
}

Question 8

Does list 2 = list 1 create a new list?

Answer 8

No, it only copied the reference to list 2

Question 9

How to copy the elements of an array to another

Answer 9

you must copy the array’s individual elements to the other array

Question 10

When passing an array to a method, what is passed to the method?

Answer 10

the reference of the array

Question 11

What is the name of an array without an explicit reference variable?

Answer 11

anonymous array

Question 12

True or false” For a parameter of a primitive type, the actual value is passed instead of a reference

Answer 12

True

Question 13

True or false: Changing the value of the local parameter inside the method changes the value of the variable outside the method

Answer 13

false

Question 14

True or false: for a parameter of an array type, the reference value is passed

Answer 14

True

Question 15

True or false: Any changes to the array that occur inside the method body does not affect the original array that was passed as the arg

Answer 15

False

Question 16

What is a heap

Answer 16

a region of memory used for dynamic memory allocation, where all Java objects are stored when they are created with the new keyword

The java virtual machine stores, for example a new array, inside the heap

Question 17

What defines a ragged array?

Answer 17

An array with different row lengths

Question 18

True or false: int a[] = new int[2]; is correct

Answer 18

True

Question 19

True or false: int a = new int[2]; is correct

Answer 19

False

Question 20

True or false: int[] a = new int(2); is correct

Answer 20

False

Question 21

True or false: int[] a = new int[2]; is correct

Answer 21

True

Question 22

What is the correct term for numbers[99]?

Answer 22

indexed variable

Question 23

Define indexed variable

Answer 23

Any variable that is accessed through the index of an array

Question 24

What method copies the sourceArray to the targetArray?

Answer 24

System.arraycopy(sourceArray, 0, targetArray, 0, sourceArray.length);

Question 25

When you pass an array to a method, the method receives_

Answer 25

the reference of the array

Question 26

The JVM stores an array in an area called _ , which used for dynamic memory allocation where blocks of memory are allocated and freed in an arbitrary order

Answer 26

Heap

Question 27

When you return an array from a method, the method returns _

Answer 27

the reference of the array

Question 28

The _ method sorts the array scores of the double[] type

Answer 28

java.util.Arrays.sort(scores);

Question 29

int[] scores = {1, 20, 30, 40, 50}, what does java.util.Arrays.toString(scores) return?

Answer 29

[1,20,30,40,50]

Question 30

True or false: the first element of matrix is = 0

int [] [] matrix = new int[5][5];

Answer 30

True