Java Arrays MCQ

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Java arrays are fundamental constructs used to store and manipulate a collection of items. Testing one’s understanding of arrays can help solidify the foundational knowledge needed to venture into more complex Java programming. In this post, we present ten multiple-choice questions to test your knowledge of Java arrays.

Each question is followed by the correct answer and an explanation to help reinforce your knowledge.

1. Which of the following best describes an array in Java?

a) An array is a data structure that can store multiple values of different data types sequentially.
b) An array is a method in the Java standard library used to manipulate data.
c) An array is a data structure that can store multiple values of the same data type sequentially.
d) An array is a keyword in Java used for conditional checks.

Answer:

c) An array is a data structure that can store multiple values of the same data type sequentially.

Explanation:

In Java, an array is a homogenous data structure that can store a fixed-size sequential collection of elements of the same type. The size of an array must be specified by an int value and not long or short.

2. How do you declare an array of integers in Java?

a) int array[]
b) array int[]
c) int[] array
d) array[] int

Answer:

Both a) int array[] and c) int[] array are correct.

Explanation:

In Java, you can declare an array in multiple ways. Both mentioned choices are commonly accepted methods.

3. Which of the following initializes an array of size 5 with default integer values?

a) int[] arr = new int[];
b) int[] arr = new int[5];
c) int arr[5];
d) int arr[] = {5};

Answer:

b) int[] arr = new int[5];

Explanation:

This will initialize an array of size 5 with default values (0 for integers).

4. What will be the default value of array elements if the array is of type float?

a) 0
b) null
c) 0.0
d) Not defined

Answer:

c) 0.0

Explanation:

For float arrays, the default values are 0.0.

5. What does the length attribute of an array represent in Java?

a) Width of the array
b) Memory size of the array
c) Number of elements the array can store
d) Total capacity allocated for the array

Answer:

c) Number of elements the array can store

Explanation:

The length attribute represents the number of elements in the array.

6. Which of the following is true about arrays in Java?

a) Arrays are always dynamic
b) Arrays can store different types of data
c) The size of arrays can be changed after initialization
d) Arrays are objects in Java

Answer:

d) Arrays are objects in Java

Explanation:

In Java, arrays are objects. They are not dynamic (their size is fixed after initialization), and they store only one type of data (e.g., only integers, or only strings).

7. How can you access the fifth element in an array named ‘data’?

a) data(4)
b) data(5)
c) data[5]
d) data[4]

Answer:

d) data[4]

Explanation:

Arrays are zero-indexed, so the fifth element is accessed with index 4.

8. What exception will be thrown if you try to access an array element beyond its size?

a) ArraySizeException
b) ArrayIndexOutOfBoundsException
c) IndexOutOfBoundException
d) SizeExceededException

Answer:

b) ArrayIndexOutOfBoundsException

Explanation:

If you try to access an array element that doesn’t exist, Java will throw this exception.

9. Which method is used to clone an array in Java?

a) copy()
b) clone()
c) duplicate()
d) replicate()

Answer:

b) clone()

Explanation:

The clone() method is used to create and return a copy of the array.

10. What is the initial value of an array of booleans in Java?

a) true
b) false
c) 0
d) null

Answer:

b) false

Explanation:

The default value for a boolean array in Java is false.

11. How do you create a two-dimensional array with 3 rows and 4 columns?

a) int[][] arr = new int[3][4];
b) int[][] arr = new int[4][3];
c) int[3][4] arr;
d) int[4][3] arr;

Answer:

a) int[][] arr = new int[3][4];

Explanation:

In Java, multi-dimensional arrays are essentially “arrays of arrays”. The first dimension specifies the number of rows and the second dimension specifies the number of columns.

12. How can you initialize an array with the values 1, 2, and 3?

a) int[] arr = int[1, 2, 3];
b) int[] arr = {1, 2, 3};
c) int arr[] = (1, 2, 3);
d) int[] arr = new {1, 2, 3};

Answer:

b) int[] arr = {1, 2, 3};

Explanation:

This is the standard way to declare and initialize an array with values in Java.

13. What is the index range for the elements of an array in Java?

a) 0 to length – 1
b) 1 to length
c) -1 to length – 1
d) 0 to length

Answer:

a) 0 to length – 1

Explanation:

The index range for the elements of an array in Java is 0 to length – 1, where length is the number of elements in the array.


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