Question 1

What is the output of the following statements? ArrayList names = new ArrayList(); Names.add("Bob"); Names.add(0, "Ann"); Names.remove(1); Names.add("Cal"); Names.set(2, "Tony"); For (String s : names) { System.out.print(s + ", "); }

Accepted Answer

The code will result in an error because the method calls are case-sensitive, and "Names" should be "names".

Question 2

What is the output of the following statements? ArrayList names = new ArrayList(); Names.add("Bob"); Names.add(0, "Ann"); Names.remove(1); Names.add("Cal"); Names.set(1, "Tony"); For (String s : names) { System.out.print(s + ", "); }

Accepted Answer

The operations on the ArrayList result in the following sequence: ["Ann"], ["Ann", "Bob"], ["Ann"], ["Ann", "Cal"], ["Ann", "Tony"]. Thus, the output is "Ann, Tony".

Question 3

What is the output of the code snippet below?
Int[][] arr =
{
{ 1, 2, 3, 0 },
{ 4, 5, 6, 0 },
{ 0, 0, 0, 0 }
};
Int val = arr[1][2] + arr[1][3];
System.out.println(val);

Accepted Answer

The answer of What is the output of the code...

Question 4

Consider the following code snippet:
Int[][] arr =
{
{ 1, 2, 3, 0 },
{ 4, 5, 6, 0 },
{ 0, 0, 0, 0 }
};
Int[][] arr2 = arr;
System.out.println(arr2[2][1] + arr2[1][2]);
What is the output of the given code snippet on execution?

Accepted Answer

The value of arr2[2][1] is 0 and arr2[1][2] is 6, so the sum is 0 + 6 = 6.

Question 5

What is the output of the following code?
Int[][] counts =
{
{ 0, 0, 1 },
{ 0, 1, 1, 2 },
{ 0, 0, 1, 4, 5 },
{ 0, 2 }
};
System.out.println(counts[3].length);

Accepted Answer

The code prints the length of the array at index 3 of the 'counts' array, which is {0, 2}. The length of this array is 2.

Question 6

Which statement is true about the code snippet below? ArrayList names = new ArrayList(); Names.add("John"); Names.add("Jerry"); ArrayList friends = new ArrayList(names); Friends.add("Harry");

Accepted Answer

The answer of Which statement is true about the code...

Question 7

Consider the following code snippet, where the array lists contain elements that are stored in ascending order: ArrayList list1 = new ArrayList(); ArrayList list2 = new ArrayList(); ) . . Int count = 0; For (int i = 0; i < list1.size() && i < list2.size(); i++) { If (list1.get(i) == list2.get(i)) { Count++; } } Which one of the following descriptions is correct for the given code snippet?

Accepted Answer

The code snippet iterates through both lists simultaneously and increments the count for each pair of elements that are equal, effectively counting the number of matches between the two lists.

Question 8

Which statement is true about the code snippet below? public static void main(String[] args) { Scanner in = new Scanner(System.in); ArrayList inputs = new ArrayList(); Int ind = 0; While (in.hasNextDouble()) { Inputs.set(ind, in.nextDouble()); Ind++; } }

Accepted Answer

The code has a run-time error because the array list is not initialized with a size, and the set() method is called on an index that is out of bounds.

Question 9

Assume the following variable has been declared and given a value as shown:
Int[] numbers = {9, 17, -4, 21 };
Which is the value of numbers.length?

Accepted Answer

The length of an array in Java is determined by the number of elements it contains. The array 'numbers' has 4 elements, so numbers.length is 4.

Question 10

What is the output of the following statements? ArrayList cityList = new ArrayList(); CityList.add("London"); CityList.add("New York"); CityList.add("Paris"); CityList.add("Toronto"); CityList.add("Hong Kong"); CityList.add("Singapore"); System.out.print(cityList.size()); System.out.print(" " + cityList.contains("Toronto")); System.out.print(" " + cityList.indexOf("New York")); System.out.println(" " + cityList.isEmpty());

Accepted Answer

The list has 6 elements, "Toronto" is in the list, "New York" is at index 1, and the list is not empty.

Question 11

When an integer literal is added to an array list declared as ArrayList<Integer>, Java performs:

Accepted Answer

When an integer literal is added to an array list declared as ArrayList<Integer>, Java performs auto-boxing. This means that the integer value is automatically converted into an Integer object before being added to the list.

Question 12

Assume the variable numbers has been declared to be an array that has at least one element. Which is the following represents the last element in numbers?

Accepted Answer

The last element in the array will always be at an index of numbers.length-1, so we need to choose option D which represents the last element in numbers array. A represents an out of bounds index, B represents the length of the array, which is not the same as the last element, and C represents an invalid negative index.

Question 13

Which one of the following is the correct code snippet for calculating the largest value in an integer array list aList?

Accepted Answer

The correct code snippet initializes `max` with the first element of the list and iterates through the list starting from the second element, updating `max` whenever a larger element is found.

Question 14

Which statement is true about the code snippet below? ArrayList names = new ArrayList(); Names.add("John"); Names.add("Jerry"); ArrayList friends = names; Friends.add("Harry");

Accepted Answer

The 'friends' list is a reference to the same object as 'names', so changes to one affect the other.

Question 15

How many elements can be stored in a two-dimensional 5 by 6 array?

Accepted Answer

A two-dimensional array with dimensions 5 by 6 can store 5 * 6 = 30 elements.

Question 16

Which one of the following statements is correct for displaying the value in the third row and the fourth column of a two-dimensional 5 by 6 array?

Accepted Answer

In programming, array indices start at 0. Therefore, the third row is index 2 and the fourth column is index 3.

Question 17

Which statement is true about the code snippet below? ArrayList names = new ArrayList(); Names.add("John"); Names.add("Jerry"); ArrayList friends = new ArrayList(names); Names.add("Harry");

Accepted Answer

The 'names' list has three elements after adding "Harry", while 'friends' is initialized with the elements of 'names' before "Harry" was added, so it has two elements.

Question 18

What should you check for when calculating the smallest value in an array list?

Accepted Answer

To calculate the smallest value in an array list, it's essential to ensure that the array list contains at least one element. Without any elements, it's impossible to determine a smallest value. The number of elements, whether the maximum or minimum value is in the first element, does not affect the ability to calculate the smallest value as long as there is at least one element to compare.

Question 19

What is the output of the code snippet below?
Int[][] numarray =
{
{ 8, 7, 6 },
{ 0, 0, 0 }
};
System.out.print(numarray[0][0]);
System.out.print(numarray[1][0]);

Accepted Answer

The code accesses the first element of the first array (8) and the first element of the second array (0), printing them sequentially as "80".

Question 20

Consider the following code snippet: public static void main(String[] args) { ArrayList names = new ArrayList(); Names.add("John"); Names.add("Jerry"); Names.add("Janet"); ArrayList names2 = reverse(names); } Public static ArrayList reverse(ArrayList names) { ArrayList result = new ArrayList(); For (int i = names.size() - 1; i >= 0; i--) { Result.add(names.get(i)); } Return result; } Which statement is true after the main method is executed?

Accepted Answer

The answer of Consider the following code snippet: public static...

Quiz 7: Arrays and Array Lists

What is the output of the following statements? ArrayList<String> names = new ArrayList<String>() ; Names.add("Bob") ; Names.add(0, "Ann") ; Names.remove(1) ; Names.add("Cal") ; Names.set(2, "Tony") ; For (String s : names) { System.out.print(s + ", ") ; }

What is the output of the following statements? ArrayList<String> names = new ArrayList<String>() ; Names.add("Bob") ; Names.add(0, "Ann") ; Names.remove(1) ; Names.add("Cal") ; Names.set(1, "Tony") ; For (String s : names) { System.out.print(s + ", ") ; }

What is the output of the code snippet below? Int[][] arr = { { 1, 2, 3, 0 }, { 4, 5, 6, 0 }, { 0, 0, 0, 0 } }; Int val = arr[1][2] + arr[1][3]; System.out.println(val) ;

Consider the following code snippet: Int[][] arr = { { 1, 2, 3, 0 }, { 4, 5, 6, 0 }, { 0, 0, 0, 0 } }; Int[][] arr2 = arr; System.out.println(arr2[2][1] + arr2[1][2]) ; What is the output of the given code snippet on execution?

What is the output of the following code? Int[][] counts = { { 0, 0, 1 }, { 0, 1, 1, 2 }, { 0, 0, 1, 4, 5 }, { 0, 2 } }; System.out.println(counts[3].length) ;

Which statement is true about the code snippet below? ArrayList<String> names = new ArrayList<String>() ; Names.add("John") ; Names.add("Jerry") ; ArrayList<String> friends = new ArrayList<String>(names) ; Friends.add("Harry") ;

Which statement is true about the code snippet below? public static void main(String[] args) { Scanner in = new Scanner(System.in) ; ArrayList<Double> inputs = new ArrayList<Double>() ; Int ind = 0; While (in.hasNextDouble() ) { Inputs.set(ind, in.nextDouble() ) ; Ind++; } }

Assume the following variable has been declared and given a value as shown: Int[] numbers = {9, 17, -4, 21 }; Which is the value of numbers.length?

When an integer literal is added to an array list declared as ArrayList<Integer>, Java performs:

Assume the variable numbers has been declared to be an array that has at least one element. Which is the following represents the last element in numbers?

Which one of the following is the correct code snippet for calculating the largest value in an integer array list aList?

Which statement is true about the code snippet below? ArrayList<String> names = new ArrayList<String>() ; Names.add("John") ; Names.add("Jerry") ; ArrayList<String> friends = names; Friends.add("Harry") ;

How many elements can be stored in a two-dimensional 5 by 6 array?

Which one of the following statements is correct for displaying the value in the third row and the fourth column of a two-dimensional 5 by 6 array?

Which statement is true about the code snippet below? ArrayList<String> names = new ArrayList<String>() ; Names.add("John") ; Names.add("Jerry") ; ArrayList<String> friends = new ArrayList<String>(names) ; Names.add("Harry") ;

What should you check for when calculating the smallest value in an array list?

What is the output of the code snippet below? Int[][] numarray = { { 8, 7, 6 }, { 0, 0, 0 } }; System.out.print(numarray[0][0]) ; System.out.print(numarray[1][0]) ;