Array -Java Programming MCQ Questions and Answers

41

What would be the result of attempting to compile and run the following code?

public class HelloWorld{
      public static void main(String[] args){
            double[] x = new double[]{1, 2, 3};
            System.out.println("Value is " + x[1]);
      }
}

A) The program has a compile error because the syntax new double[]{1, 2, 3} is wrong and it should be replaced by {1, 2, 3}. B) The program has a compile error because the syntax new double[]{1, 2, 3} is wrong and it should be replaced by new double[3]{1, 2, 3}; C) The program has a compile error because the syntax new double[]{1, 2, 3} is wrong and it should be replaced by new double[]{1.0, 2.0, 3.0}; D) The program compiles and runs fine and the output

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Answer & Solution

Answer: Option D

Solution:

new double[]{1, 2, 3} is correct. This is the syntax I have not covered in this edition, but will be covered in the future edition. In this question, double[] x = new double[]{1, 2, 3} is equivalent to double[] x = {1, 2, 3};

42

Which will legally declare, construct, and initialize an array?

A) int [] myList = {}; B) int [] myList = (5, 8, 2); C) int myList [] [] = {4,9,7,0}; D) int myList [] = {4, 3, 7};

Discuss

Answer & Solution

Answer: Option D

Solution:

The only legal array declaration and assignment statement is Option D
Option A is wrong because it initializes an int array with String literals.
Option B is wrong because it uses something other than curly braces for the initialization.
Option C is wrong because it provides initial values for only one dimension, although the declared array is a two-dimensional array.

43

What will be the output of the program?

public class Test{
      public static void main(String [] args){
            String s1 = args[1];
            String s2 = args[2];
            String s3 = args[3];
            String s4 = args[4];
            System.out.print(" args[2] = " + s2);
      }
}

and the command-line invocation is C:Java> java Test 1 2 3 4

A) args[2] = 2 B) args[2] = 3 C) args[2] = null D) An exception is thrown at runtime.

Discuss

Answer & Solution

Answer: Option D

Solution:

An exception is thrown because in the code String s4 = args[4];, the array index (the fifth element) is out of the bounds. The exception thrown is the ArrayIndexOutOfBoundsException.

44

What is the value of a[1] after the following code is executed?

int[] a = {0, 2, 4, 1, 3};
for(int i = 0; i < a.length; i++)
a[i] = a[(a[i] + 3) % a.length];

A) 0 B) 1 C) 2 D) 3 E) 4

Discuss

Answer & Solution

Answer: Option B

Solution:

Here's an explanation of the code:

1. The array a is initialized with values: {0, 2, 4, 1, 3}.
2. The for loop iterates over each element of the array using the variable i.
3. Inside the loop, the value of a[i] is updated using the expression a[(a[i] + 3) % a.length].
(i) For i = 0, a[i] is 0. So, a[(0 + 3) % 5] becomes a[3 % 5] which is a[3] (value 1).
(ii) For i = 1, a[i] is 2. So, a[(2 + 3) % 5] becomes a[5 % 5] which is a[0] (value 0).
(iii) For i = 2, a[i] is 4. So, a[(4 + 3) % 5] becomes a[7 % 5] which is a[2] (value 4).
(iv) For i = 3, a[i] is 1. So, a[(1 + 3) % 5] becomes a[4 % 5] which is a[4] (value 3).
(v) For i = 4, a[i] is 3. So, a[(3 + 3) % 5] becomes a[6 % 5] which is a[1] (value 2).
4. After the loop finishes, the modified array a becomes {0, 1, 4, 3, 2}.
5. Finally, the code prints the value of a[1] using System.out.println(a[1]), which outputs 1.

Therefore, the output of the code is 1.

45

Predict the output:

public class Test{
public static void main(String... args){
            int[] index = new int[5];
            System.out.println(index instanceof Object);
      }
}

A) true B) false C) Compilation fails with an error at line 3 D) Compilation fails with an error at line 4 E) None of these

Discuss

Answer & Solution

Answer: Option A

Solution:

An array is always an instance of Object.

46

Which of these operators is used to allocate memory to array variable in Java?

A) malloc B) alloc C) new D) new malloc

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Answer & Solution

Answer: Option C

No explanation is given for this question. Let's Discuss on Board

47

Which of these is an incorrect array declaration?

A) int arr[] = new int[5] B) int [] arr = new int[5] C) int arr[] = new int arr[5] D) int arr[] = int [5] new

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Answer & Solution

Answer: Option D

No explanation is given for this question. Let's Discuss on Board

48

What will be the output of the following Java code?

int arr[] = new int [5];
System.out.print(arr);

A) 0 B) value stored in arr[0] C) 00000 D) Class name@ hashcode in hexadecimal form

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Answer & Solution

Answer: Option D

No explanation is given for this question. Let's Discuss on Board

49

What will be the output of the following Java code?

class array_output 
{
    public static void main(String args[]) 
    {
        int array_variable [] = new int[10];
  for (int i = 0; i < 10; ++i) 
        {
            array_variable[i] = i;
            System.out.print(array_variable[i] + " ");
            i++;
        }
    } 
}

A) 0 2 4 6 8 B) 1 3 5 7 9 C) 0 1 2 3 4 5 6 7 8 9 D) 1 2 3 4 5 6 7 8 9 10

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Answer & Solution

Answer: Option A

No explanation is given for this question. Let's Discuss on Board

50

What will be the output of the following Java code?

class evaluate 
{
    public static void main(String args[]) 
        {
      int arr[] = new int[] {0 , 1, 2, 3, 4, 5, 6, 7, 8, 9};
      int n = 6;
            n = arr[arr[n] / 2];
      System.out.println(arr[n] / 2);
        } 
}

A) 3 B) 0 C) 6 D) 1

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Answer & Solution

Answer: Option D

No explanation is given for this question. Let's Discuss on Board