Easy Java Arrays MCQs for Practice

Java Arrays are fundamental for storing multiple values in a single variable. Whether you’re new to Java or looking to strengthen your basics, practicing Java Arrays MCQs can be incredibly beneficial for solidifying your understanding and improving your coding skills.

Here is the basic syntax of an array in Java:

datatype[] arrayName = new datatype[size];

You can also explore more about arrays on Oracle’s official Java documentation.

Java Arrays MCQs (Easy)

Now, let’s test your knowledge with some multiple-choice questions focused on Java arrays.

Question 1:

What is the default value of an uninitialized element in an integer array in Java?

A null

B Garbage value

C 0

D undefined

View Answer

Correct Answer: C

In Java, the default value for integer array elements is 0 when the array is initialized. Option 0 is correct.

Question 2:

Which of the following correctly declares a 2D array in Java?

A All of the above

B int arr[][] = new int[3][3];

C int[][] arr = new int[3][3];

D int[] arr = new int[3][3];

View Answer

Correct Answer: A

In Java, a 2D array can be declared using any of the listed syntax. All of them are valid ways to declare a 2D array.

Question 3:

What is the output of the following code?

int[] arr = {1, 2, 3, 4};
System.out.println(arr[2]);

A 1

B 4

C 3

D 2

View Answer

Correct Answer: C

Array indexing starts from 0 in Java. The element at index 2 is 3, so option 2 is correct.

Question 4:

How do you initialize an array with 5 elements in Java?

A int[] arr = new int[5];

B int arr[] = new int[5];

C Both A and B

D int[] arr = {5};

View Answer

Correct Answer: C

Both `int[] arr = new int[5];` and `int arr[] = new int[5];` are valid ways to initialize an array with 5 elements.

Question 5:

What will be the output of the following code?

int[] arr = {10, 20, 30};
System.out.println(arr[3]);

A 20

B 30

C ArrayIndexOutOfBoundsException

D 10

View Answer

Correct Answer: C

Array indices in Java are 0-based. Trying to access index 3 will throw an ArrayIndexOutOfBoundsException, as the valid indices are 0, 1, and 2.

Question 6:

Which method is used to copy the elements of one array to another in Java?

A clone()

B copy()

C Arrays.copyOf()

D None of the above

View Answer

Correct Answer: C

The `Arrays.copyOf()` method is used to copy the elements of an array to another array in Java.

Question 7:

Which of the following statements is true about Java arrays?

A Arrays can hold different types of elements.

B Arrays are objects in Java.

C Arrays are always passed by value.

D Arrays are dynamically sized.

View Answer

Correct Answer: B

Arrays in Java are objects. They are passed by reference, not by value, and their size is fixed once initialized.

Question 8:

What is the output of the following code?

int[] arr = {1, 2, 3};
System.out.println(arr.length);

A 2

B 3

C 4

D 1

View Answer

Correct Answer: B

The length of the array `arr` is 3 since it contains three elements. Option 2 is correct.

Question 9:

What is the result of the following code?

int[] arr = {10, 20, 30};
arr[1] = 50;
System.out.println(arr[1]);

A 20

B 30

C 50

D 10

View Answer

Correct Answer: C

The value at index 1 is updated to 50, so the output will be 50.

Question 10:

Which of the following is true about a jagged array in Java?

A It is always a fixed-size array.

B It cannot hold null values.

C It is a 2D array where each row has the same number of columns.

D It is an array where each row can have a different number of columns.

View Answer

Correct Answer: D

A jagged array in Java is an array of arrays where each row can have a different number of columns.

Question 11:

What is the output of the following code?

int[] arr = {1, 2, 3};
for (int i = 0; i < arr.length; i++) {
    System.out.print(arr[i] + " ");
}

A 1 2 3

B Compilation error

C 1 2 3 4

D 3 2 1

View Answer

Correct Answer: A

The code correctly prints all elements of the array in order: `1 2 3`.

Question 12:

Which of the following will result in an ArrayIndexOutOfBoundsException?

A None of the above

B int[] arr = new int[5]; arr[4] = 10;

C int[] arr = new int[5]; arr[5] = 10;

D int[] arr = new int[5]; arr[3] = 10;

View Answer

Correct Answer: C

Array indices in Java are 0-based. Therefore, attempting to access index 5 in an array of size 5 will throw an ArrayIndexOutOfBoundsException.

Question 13:

How would you initialize an array of size 3 to store the values 1, 2, and 3?

A int arr[] = new int[3]{1, 2, 3};

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

C None of the above

D int[] arr = new int[3]; arr = {1, 2, 3};

View Answer

Correct Answer: B

The correct syntax to initialize an array with values is `int[] arr = {1, 2, 3};`.

Question 14:

What is the output of the following code?

int[] arr = {5, 10, 15};
for (int i = 0; i < arr.length; i++) {
    if (i == 1) continue;
    System.out.print(arr[i] + " ");
}

A 5 10 15

B 10 15

C 5 15

D 5

View Answer

Correct Answer: C

The `continue` statement skips the iteration when `i == 1`. Therefore, the output will be `5 15`.

Question 15:

Which method is used to sort an array in Java?

A None of the above

B sort()

C Arrays.sort()

D Collections.sort()

View Answer

Correct Answer: C

The `Arrays.sort()` method is used to sort arrays in Java.

Question 16:

What is the index of the last element in an array of size 5?

A 4

B 0

C -1

D 5

View Answer

Correct Answer: A

In Java, array indices start at 0. Therefore, the index of the last element in an array of size 5 is 4.

Question 17:

What happens if you try to assign a value of a different type to an array element?

A It is automatically converted

B Compilation error

C Runtime error

D Nothing happens

View Answer

Correct Answer: B

If you try to assign a value of a different type to an array element, it results in a compilation error in Java.

Question 18:

How can you convert an array to a list in Java?

A None of the above

B Using List.addAll()

C Using new ArrayList()

D Using Arrays.asList()

View Answer

Correct Answer: D

You can use the `Arrays.asList()` method to convert an array to a list in Java.

Question 19:

Which of the following is correct about arrays in Java?

A Array elements must be of different types.

B Arrays are always passed by value.

C Array size is dynamic.

D Arrays are passed by reference.

View Answer

Correct Answer: D

Arrays in Java are passed by reference, meaning changes to the array inside a method will reflect outside the method as well.

Question 20:

What is the result of the following code?

int[] arr = {5, 10, 15};
System.out.println(arr[arr.length - 1]);

A 5

B 10

C 15

D ArrayIndexOutOfBoundsException

View Answer

Correct Answer: C

The expression `arr.length – 1` refers to the last index of the array, which is 2. Therefore, the value at index 2 is 15.

Question 21:

What will be the output of the following code?

int[] arr = new int[3];
arr[0] = 1;
arr[1] = 2;
arr[2] = 3;
System.out.println(arr[5]);

A 1

B ArrayIndexOutOfBoundsException

C 2

D 3

View Answer

Correct Answer: B

Array indices in Java are 0-based. The array has only 3 elements, so trying to access index 5 will throw an ArrayIndexOutOfBoundsException.

Question 22:

Which of the following is the correct way to create a multidimensional array with 2 rows and 3 columns in Java?

A int[][] arr = new int[2][3];

B int[] arr = new int[3][2];

C int[2][3] arr = new int[][];

D int[] arr = new int[2][3];

View Answer

Correct Answer: A

The correct way to create a 2D array with 2 rows and 3 columns is `int[][] arr = new int[2][3];`.

Question 23:

What is the value of arr[0] after executing the following code?

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

A 1

B 0

C 2

D 3

View Answer

Correct Answer: B

After the second line of code, the array is reinitialized with size 2. The default value of integer array elements is 0, so `arr[0]` will be 0.

Question 24:

What happens if you try to access an uninitialized element of an array in Java?

A Nothing happens.

B It returns a default value depending on the array type.

C It causes an error at compile time.

D It throws a NullPointerException.

View Answer

Correct Answer: B

In Java, uninitialized elements of an array are assigned default values, such as 0 for integers and null for object references.

Question 25:

What is the output of the following code?

int[] arr = {1, 2, 3, 4};
arr[0] = 5;
arr[1] = arr[0] + arr[3];
System.out.println(arr[1]);

A 7

B 5

C 10

D 9

View Answer

Correct Answer: D

The value of `arr[1]` becomes the sum of `arr[0]` (which is 5) and `arr[3]` (which is 4). Therefore, `arr[1]` becomes 9.

Question 26:

What is the result of the following code?

int[] arr = {1, 2, 3, 4};
arr = new int[5];
System.out.println(arr[4]);

A 4

B ArrayIndexOutOfBoundsException

C 0

D 1

View Answer

Correct Answer: C

When an array is initialized with a size of 5, all its elements are set to their default values (0 for integers). `arr[4]` will be 0.

Question 27:

Which of the following will cause a compile-time error?

A int[] arr = {1, 2, 3}; arr[5] = 10;

B int[] arr = new int[3]; arr[0] = 5;

C int arr[5] = {1, 2, 3};

D int[] arr = new int[2]; arr[1] = 10;

View Answer

Correct Answer: C

Option 3 causes a compile-time error because the array must be initialized with curly braces `{}` directly after its declaration. `int arr[5] = {1, 2, 3};` is incorrect.

Question 28:

What is the output of the following code?

int[] arr = new int[3];
System.out.println(arr[2]);

A Undefined

B ArrayIndexOutOfBoundsException

C 0

D null

View Answer

Correct Answer: C

Array elements are initialized to 0 by default, so `arr[2]` will output 0.

Question 29:

Which of the following is true about arrays in Java?

A Arrays in Java are always dynamically sized.

B Arrays can store elements of different types.

C The size of an array in Java is fixed once it is initialized.

D Arrays in Java can be resized during execution.

View Answer

Correct Answer: C

In Java, once an array is created, its size is fixed and cannot be changed. Option 2 is correct.

Question 30:

What will happen if you attempt to access a null array in Java?

A Compilation error

B It will return null.

C NullPointerException

D ArrayIndexOutOfBoundsException

View Answer

Correct Answer: C

If you try to access an array that is null, it will result in a `NullPointerException`.

Question 31:

What is the output of the following code?

int[] arr = {1, 2, 3, 4};
arr = new int[4];
System.out.println(arr[0]);

A 0

B 1

C ArrayIndexOutOfBoundsException

D 4

View Answer

Correct Answer: A

When a new array is created with the same size, all elements are initialized to their default value, which is 0 for integers.

Question 32:

How can you initialize a 2D array with the following values: `{{1, 2}, {3, 4}}`?

A int[][] arr = new int[2][2];

B int[][] arr = new int[2]; arr[0] = {1, 2}; arr[1] = {3, 4};

C int[][] arr = {{1, 2}, {3, 4}};

D int[] arr = {1, 2, 3, 4};

View Answer

Correct Answer: C

The correct way to initialize a 2D array with the values `{{1, 2}, {3, 4}}` is `int[][] arr = {{1, 2}, {3, 4}};`.

Question 33:

What is the result of the following code?

int[] arr = new int[3];
arr[0] = 1;
arr[1] = 2;
arr[2] = 3;
System.out.println(Arrays.toString(arr));

A [0, 0, 0]

B [1, 2, 3]

C Compilation error

D [1, 2, 3, 0]

View Answer

Correct Answer: B

The `Arrays.toString()` method converts the array into a string representation. The output will be `[1, 2, 3]`.

Question 34:

What is the output of the following code?

int[] arr = {1, 2, 3};
arr = new int[]{4, 5, 6};
System.out.println(arr[0]);

A 5

B 6

C 4

D 1

View Answer

Correct Answer: C

The array is reinitialized with the values `{4, 5, 6}`, so `arr[0]` will output `4`.

Question 35:

Which of the following will correctly copy the elements of one array to another?

A None of the above

B arr = new int[5]; arr.copyFrom(arr2);

C arr = Arrays.copyOf(arr2, arr2.length);

D arr = arr2;

View Answer

Correct Answer: C

The correct method to copy an array is `Arrays.copyOf(arr2, arr2.length);`.

Question 36:

Which of the following will print the elements of a 2D array in a single line?

A System.out.println(Arrays.toString(arr));

B System.out.println(Arrays.deepToString(arr));

C System.out.println(arr);

D None of the above

View Answer

Correct Answer: B

The `Arrays.deepToString()` method prints the elements of a 2D array in a readable format.

Question 37:

What will happen if you try to access an index outside the bounds of a 2D array?

A No error

B NullPointerException

C IndexOutOfBoundsException

D ArrayIndexOutOfBoundsException

View Answer

Correct Answer: D

Attempting to access an index outside the bounds of a 2D array will result in an `ArrayIndexOutOfBoundsException`.

Question 38:

What is the output of the following code?

int[][] arr = {{1, 2}, {3, 4}};
System.out.println(arr[1][1]);

A 4

B 3

C 2

D 1

View Answer

Correct Answer: A

The value at index `[1][1]` in the 2D array is `4`.

Question 39:

What is the result of calling `Arrays.sort()` on a non-sorted array?

A It throws an exception.

B It sorts the array in ascending order.

C It leaves the array unchanged.

D It sorts the array in descending order.

View Answer

Correct Answer: B

The `Arrays.sort()` method sorts the elements of an array in ascending order.

Question 40:

What is the result of trying to assign a new value to an element of a final array reference?

A It throws a runtime exception.

B You can assign a new value.

C It throws a compile-time error.

D You cannot assign a new value.

View Answer

Correct Answer: B

Even though an array reference is `final`, you can still modify its elements. The `final` keyword only prevents reassigning the reference itself.

Java Arrays MCQs (Easy)

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