Level 4 - Arrays

Question 1

Declare an array of integers called ‘values’ with room to store 10 integers

Answer 1

int[] values = new int[10];

Question 2

What value displays?

int[] nums = {10, 3, 4, 5, 6, 7, 5};

System.out.println( nums[2]);

Answer 2

4

Question 3

What is output?

int[] list = new int[3];

list[1] = 2;

System.out.println(list.length);

Answer 3

3

//list[0] and list[2] both have a value of 0

Question 4

What value displays?

int[] nums = {5, 1, 34, 12, 11, 71, 5};

System.out.println( nums[7]);

Answer 4

Array out of bounds runtime exception - the last element is nums[6]

Question 5

Describe what the following code segment does:

for(int i=0; i < nums.length; i++)

nums[i] = Math.abs(nums[i]);

Answer 5

makes everything in the array nums positive

Question 6

Write a loop that locates the first occurrence of a negative integer in an array called ‘list’. When the loop is finished, the variable should contain the index of the negative number. The variable should be -1 if there was no negatives

Answer 6

int pos = -1;

for(int i =0; i < list.length; i++)

{

if(list[i] < 0)

pos = i;

}

return pos;

Question 7

Write a loop that displays the length of all the Strings in a string array called ‘someText’

Answer 7

for (int i =0; i < someText.length(); i++)

System.out.println( someText[i].length() );

Question 8

What value displays?

String[] pets = {“dog”, “cat”, “fish”, “pig”, “hamster”}; System.out.println( pets[1]);

Answer 8

cat

Question 9

What value displays?

String[] pets = {“dog”, “cat”, “fish”, “pig”, “hamster”}; System.out.println( pets[2].length());

Answer 9

4

//the pet at position 2 was ‘fish’ and it had 4 characters

Question 10

What value displays?

String[] pets = {“dog”, “cat”, “fish”, “pig”, “hamster”};

System.out.println( pets.length);

Answer 10

5

// .length asks how many spots in the array

Question 11

What value displays?

String[] pets = {“dog”, “cat”, “fish”, “pig”, “hamster”};

System.out.println( pets[3]+pets[0]);

Answer 11

pigdog

Question 12

Use a for loop to fill an array called ‘randoms’ with a random number from 1-100. (assume the array has been created)

Answer 12

for (int i=0; i < randoms.length; i++)

{

randoms[i] = (int)(Math.random()*100)+1;

}

Question 13

What is the issue with this array?

int [] numbers = new int [4];

numbers[1] = 3;

numbers[2] = 56;

numbers[3] = 34;

numbers[4] = 2;

Answer 13

“numbers[4]” is out of bounds of the array.

Question 14

Write a line of code that displays the length of the array: dogfight

Answer 14

System.out.print(dogfight.length);

Question 15

How does this change each element of the array?

for (int i = 0; i < b.length; i++)

{

b[i] += 3;

}

Answer 15

The loop adds 3 to each element of the array “b.”