Question 1

When the order of the elements is unimportant, what is the most efficient way to remove an element from an array?
A) Delete the element and move each element after that one to a lower index.
B) Replace the element to be deleted with the last element in the array.
C) Replace the element to be deleted with the first element in the array.
D) Replace the element with the next element.

Accepted Answer

When the order of elements is unimportant, the most efficient way to remove an element from an array is to replace it with the last element in the array. This way, there is no need to shift any elements over to fill the gap left by the removed element. The time complexity of this approach is O(1), which is the most efficient way.

Question 2

Which statements are true about the buffer overrun attack launched over the Internet in 1988?
I. The buffer overrun exploited a program that was written in C running on the Unix operating system
II. The Java programming language generates a run-time exception when buffer overrun occurs
III. In recent years computer attacks have lessened
A) I, II
B) I, III
C) II, III
D) I, II, III

Accepted Answer

A

Question 3

Identify the correct statement for defining an integer array named numarray of ten elements.
A) int[] numarray = new int[9];
B) int[] numarray = new int[10];
C) int[10] numarray;
D) int numarray[10];

Accepted Answer

The correct statement for defining an integer array named numarray of ten elements is "int[] numarray = new int[10];". Option A creates an array of 9 elements, which does not meet the requirement. Option C has the size assigned to the type int, which is incorrect syntax. Option D is also incorrect syntax as the size should be assigned after the identifier name "numarray".

Question 4

Which one of the following statements is correct for the given code snippet?
Int[] number = new int[3]; // Line 1
Number[3] = 5; // Line 2
A) Line 2 declares and initializes an array of three elements with value 5.
B) Line 2 causes a bounds error because 3 is an invalid index number.
C) Line 2 initializes the third element of the array with value 5.
D) Line 2 initializes all the elements of the array with value 5.

Accepted Answer

Line 2 causes a bounds error because 3 is an invalid index number. The array is created with size 3, which means it has indexes 0, 1, and 2. Trying to access index 3 will result in an out-of-bounds error.

Question 5

Which one of the following statements is correct about the given code snippet?
Int[] somearray = new int[6];
For (int i = 1; i < 6; i++)
{
Somearray[i] = i + 1;
}
A) The for loop initializes all the elements of the array.
B) The for loop initializes all the elements except the first element.
C) The for loop initializes all the elements except the last element.
D) The for loop initializes all the elements except the first and last elements.

Accepted Answer

The for loop initializes all the elements except the first element because the loop starts at 1 and ends at 5, leaving the first element with the default value of 0.

Question 6

What is the result of the following code?
For (double element : values)
{
Element = 0;
}
A) The elements of the array values are initialized to zero.
B) The elements of the array element are initialized to zero.
C) The first element of the array values is initialized to zero.
D) The array values is not modified.

Accepted Answer

The code is using a for-each loop to iterate through the elements of the array "values". However, the variable "element" is just a temporary variable used to hold the current element value during each iteration. Setting "element" to zero has no effect on the original array "values". Therefore, the array "values" is not modified by this code, and the answer is D.

Question 7

Which one of the following statements is a valid initialization of an array named somearray of ten elements?
A) int[] somearray = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
B) int somearray[] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
C) int[10] somearray = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
D) int somearray[10] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };

Accepted Answer

Option A is the valid initialization of an array named somearray of ten elements. Option B is also valid but it is putting 11 elements instead of 10. Option C and D are invalid syntax in Java.

Question 8

Complete the following code snippet with the correct enhanced for loop so it iterates over the array without using an index variable.
String[] arr = { "abc", "def", "ghi", "jkl" };
___________________
{
System.out.print(str);
}
A) for (String str : arr)
B) for (str : String arr)
C) for (str[] : arr)
D) for (arr[] : str)

Accepted Answer

The enhanced for loop for iterating over an array of strings should be written as "for (String str : arr)". This way, the loop will automatically iterate through each element of the array without needing an index variable.

Question 9

What is the result of executing this code snippet?
Int[] marks = { 90, 45, 67 };
For (int i = 0; i <= 3; i++)
{
System.out.println(marks[i]);
}
A) The code snippet does not give any output.
B) The code snippet displays all the marks stored in the array without any redundancy.
C) The code snippet causes a bounds error.
D) The code snippet executes an infinite loop.

Accepted Answer

The loop will run 4 times as the condition i<=3 is true for i=0,1,2 and 3. However, the array has only 3 elements, hence when i=3, the code tries to access the 4th element which does not exist and causes a ArrayIndexOutOfBoundsException.

Question 10

When an array myArray is only partially filled, how can the programmer keep track of the current number of elements?
A) access myArray.length()
B) maintain a companion variable that stores the current number of elements
C) access myArray.currentElements()
D) access myArray.length() - 1

Accepted Answer

Since the array is only partially filled, the length of the array will be greater than the actual number of elements. Therefore, the programmer needs to maintain a companion variable that stores the current number of elements to keep track of them.

Question 11

Suppose you wish to write a method that returns the sum of the elements in the partially filled array myArray. Which is a reasonable method header?
A) public static int sum(int[] values)
B) public static int sum()
C) public static int sum(int[] values, int currSize)
D) public static int sum(int[] values, int size, int currSize)

Accepted Answer

The method needs to know the current size of the array in order to sum only the elements that have been filled. Therefore, option C is the best choice as it includes a parameter for the current size of the array. Option A is not specific enough as it does not take into account the partially filled nature of the array. Option B does not have any parameters to work with, making it impossible to calculate the sum. Option D includes a redundant parameter for the total size of the array, which is not necessary for calculating the sum.

Question 12

What is displayed after executing the given code snippet?
Int[] mymarks = new int[10];
Int total = 0;
Scanner in = new Scanner(System.in);
For (int cnt = 1; cnt <= 10; cnt++)
{
System.out.print("Enter the marks: ");
Mymarks[cnt] = in.nextInt();
Total = total + mymarks[cnt];
}
System.out.println(total);
A) The code snippet displays the total marks of all ten subjects.
B) The for loop causes a run-time time error on the first iteration.
C) The code snippet causes a bounds error.
D) The code snippet displays zero.

Accepted Answer

The answer of What is displayed after executing the given...

Question 13

What is the output of the following code snippet?
Int[] myarray = { 10, 20, 30, 40, 50 };
System.out.print(myarray[2]);
System.out.print(myarray[3]);
A) 1050
B) 2030
C) 3040
D) 4050

Accepted Answer

The first line initializes an integer array with values 10, 20, 30, 40 and 50. 
The second line prints the value at index 2 which is 30. 
The third line prints the value at index 3 which is 40. 
Therefore, the output will be 3040.

Question 14

In a partially filled array, the number of slots in the array that are not currently used is
A) the length of the array minus the number of elements currently in the array
B) the number of elements currently in the array minus the length of the array
C) the length of the array plus the number of elements currently in the array
D) the number of elements currently in the array

Accepted Answer

The number of slots in the array that are not currently used can be obtained by subtracting the number of elements currently in the array from the length of the array. This is because the length of the array represents the total number of slots available, and the number of elements currently in the array represents the number of slots that are currently being used. Subtracting the number of used slots from the total slots gives the number of empty slots. Therefore, A is the best choice.

Question 15

Which statements about the enhanced for loop are true?
I. It is suitable for all array algorithms
II. It does not allow the contents of the array to be modified
III. It does not require the use of an index variable
A) I, II
B) I, III
C) II, III
D) I, II, III

Accepted Answer

The enhanced for loop does not allow modification of the array elements and does not require an index variable, but it is not suitable for all array algorithms, especially those that require modifying elements or accessing indices.

Question 16

The enhanced for loop
A) is convenient for traversing all elements in an array
B) is convenient for traversing elements in a partially filled array
C) is only used for arrays of integers
D) is used to initialize all array elements to a common value

Accepted Answer

The enhanced for loop is commonly used for traversing all elements in an array. It simplifies the code by having a built-in loop variable that can be used to access each element in the array without worrying about index values.

Question 17

What is the valid range of index values for an array of size 10?
A) 0 to 10
B) 1 to 9
C) 1 to 10
D) 0 to 9

Accepted Answer

In most programming languages, arrays are zero-indexed, meaning the first element has an index of 0 and the last element has an index of (size-1). Therefore, for an array of size 10, the valid range of index values is 0 to 9. Choice A includes 10 as a valid index value, which is out of bounds. Choice B and C exclude the first element, which is also out of bounds.

Question 18

What is the output of the given code snippet?
Int[] mynum = new int[5];
For (int i = 1; i < 5; i++)
{
Mynum[i] = i + 1;
System.out.print(mynum[i]);
}
A) 2345
B) 1234
C) 1345
D) 1111

Accepted Answer

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

Question 19

Which code snippet prints out the elements in a partially filled array of integers?
A) for (int i = 0; i < myArray.length(); i++)
{
System.out.print(myArray[i]);
}
B) for (int i = 0; i < myArray.currLength(); i++)
{
System.out.print(myArray[i]);
}
C) for (int i = 0; i < currLength; i++)
{
System.out.print(myArray[i]);
}
D) for (int i = 0; i < myArray.length(); i++)
{
System.out.print(myArray[currLength]);
}

Accepted Answer

Option C correctly accesses the partially filled array's elements by using currLength as the limit of the loop counter, and myArray[i] to access each element sequentially. Options A and D contain syntax errors that prevent the code from running correctly. In option B, currLength is not used to limit the loop counter, which could result in accessing unallocated memory in the array.

Question 20

Consider the following line of code:
Int[] somearray = new int[30];
Which one of the following options is a valid line of code for displaying the twenty-eighth element of somearray?
A) System.out.println(somearray[28]);
B) System.out.println(somearray(28));
C) System.out.println(somearray(27));
D) System.out.println(somearray[27]);

Accepted Answer

To access a specific element in an array, we use square brackets, so the correct syntax to display the value of the twenty-eighth element of somearray is somearray[27], as arrays in Java are zero-indexed. Therefore, the correct option is D, System.out.println(somearray[27]). Option A is also correct, but it displays the value of the twenty-ninth element, not the twenty-eighth. Options B and C are invalid as parentheses cannot be used to access an element in an array.

Quiz 6: Arrays and Arraylists

When the order of the elements is unimportant, what is the most efficient way to remove an element from an array?

Identify the correct statement for defining an integer array named numarray of ten elements.

Which one of the following statements is correct for the given code snippet? Int[] number = new int[3]; // Line 1 Number[3] = 5; // Line 2

Which one of the following statements is correct about the given code snippet? Int[] somearray = new int[6]; For (int i = 1; i < 6; i++) { Somearray[i] = i + 1; }

What is the result of the following code? For (double element : values) { Element = 0; }

Which one of the following statements is a valid initialization of an array named somearray of ten elements?

Complete the following code snippet with the correct enhanced for loop so it iterates over the array without using an index variable. String[] arr = { "abc", "def", "ghi", "jkl" }; ___________________ { System.out.print(str) ; }

What is the result of executing this code snippet? Int[] marks = { 90, 45, 67 }; For (int i = 0; i <= 3; i++) { System.out.println(marks[i]) ; }

When an array myArray is only partially filled, how can the programmer keep track of the current number of elements?

Suppose you wish to write a method that returns the sum of the elements in the partially filled array myArray. Which is a reasonable method header?

What is the output of the following code snippet? Int[] myarray = { 10, 20, 30, 40, 50 }; System.out.print(myarray[2]) ; System.out.print(myarray[3]) ;

In a partially filled array, the number of slots in the array that are not currently used is

Which statements about the enhanced for loop are true? I. It is suitable for all array algorithms II. It does not allow the contents of the array to be modified III. It does not require the use of an index variable

The enhanced for loop

What is the valid range of index values for an array of size 10?

What is the output of the given code snippet? Int[] mynum = new int[5]; For (int i = 1; i < 5; i++) { Mynum[i] = i + 1; System.out.print(mynum[i]) ; }

Which code snippet prints out the elements in a partially filled array of integers?

Consider the following line of code: Int[] somearray = new int[30]; Which one of the following options is a valid line of code for displaying the twenty-eighth element of somearray?