Multiple Choice Questions & Answers – Java

vibssingh

Java – Multiple Choice Questions and Answers – Arrays

Last Updated On

HOME

Welcome to the Java Quiz! This blog post features 25 multiple-choice questions that explore the concepts of Arrays in Java.

1. What is an array in Java?

a) A data structure that can hold elements of different types
b) A class that allows storing single data type elements in a contiguous memory location
c) A collection of elements in no specific order
d) A method for sorting elements

Answer 1

b) A class that allows storing single data type elements in a contiguous memory location

Arrays in Java are used to store multiple values of the same data type in a contiguous memory location.

2. How do you instantiate an array of integers with 10 elements in Java?

a) int[] arr = new int[10];
b) int arr = new int(10);
c) int arr[10] = new int[];
d) int(10) arr = new int[];

Answer 2

a) int[] arr = new int[10];

3. What is the default value of an element in an int array in Java?

Choose one option

a) 1
b) 0
c) null
d) Undefined

Answer 3

b) 0

In Java, arrays of primitive types like int are initialized to their default values. The default value for int is 0

4. What will be the output of the following Java program?

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++;
            }
        } 
   }

Choose one option

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

Answer 4

a) 0 2 4 6 8

When an array is declared using new operator then all of its elements are initialized to 0 automatically. for loop body is executed 5 times as whenever controls comes in the loop i value is incremented twice, first by i++ in body of loop then by ++i in increment condition of for loop.

5. What is the maximum number of dimensions an array can have in Java?

a) 1
b) 255
c) 2
d) No theoretical limit

Answer 5

b) 255 

Java allows arrays to have up to 255 dimensions.

6. What will be the output of the following Java program?

public class array_output {

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

Choose one option

a) 1 2 3 4 5 6 7 8 9 10
b) 0 1 2 3 4 5 6 7 8 9 10
c) i j k l m n o p q r
d) i i i i i i i i i i

Answer 6

d) i i i i i i i i i i

When an array is declared using the new operator, all of its elements are automatically initialized to default values—0 for numeric types, null for reference types, and ‘\0’ (null character) for char.

7. What will be the output of the following Java program?

public class array_output {
    public static void main(String args[])
    {
        double num[] = {5.5, 10.1, 11, 12.8, 56.9, 2.5};
        double result;
        result = 0;
        for (int i = 0; i < 6; ++i)
            result = result + num[i];
            System.out.print(result/6);

    }
}

Choose one option

a) 16.34
b) 16.566666644
c) 16.46666666666667
d) 16.46666666666666

Answer 7

c) 16.46666666666667

8. What happens if you try to access an index of an array that is out of bounds?

Choose one option

a) Compile-time error
b) Returns null
c) Throws ArrayIndexOutOfBoundsException
d) None of the above

Answer 8

c) Throws ArrayIndexOutOfBoundsException

9. How do you declare an array of strings?

a) String[] arr;
b) String arr[];
c) String arr();
d) String arr{};

Answer 9

a) String[] arr;

This is the standard way of declaring an array of strings in Java.

10. Which of the following is a valid declaration and initialization of String array in Java

a) String[] names ={“Tim”,”Mark”,”Charlie”}
b) String names[] ={“Tim”,”Mark”,”Charlie”}
c) String[3] names ={“Tim”,”Mark”,”Charlie”}
d) Both a) and b)
e) Both a) and c)

Answer 10

d) Both a) and b)

String[3] names = {“Tim”, “Mark”, “Charlie”};` is incorrect because Java does not allow specifying the size of the array within square brackets during initialization in this manner.

11. What will be the output?

public class Test {
    public static void main(String[] args) {
        String[] arr = {"Java", "Python", "C++"};
       System.out.println(arr[1]);
    }
}

Choose one option

a) Java
b) Python
c) C++
d) Compilation error

Answer 11

b) Python

arr[1] accesses the second element of the array, which is “Python”.

12.  Which of the following statements is true?

Choose one option

a) Arrays are immutable
b) Arrays are objects
c) Arrays store elements of any data type
d) Arrays automatically grow

Answer 12

b) Arrays are objects

In Java, arrays are objects and are part of the java.lang package.

13. What is the primary use of the `System.arraycopy()` method in Java?

Choose one option

a) To copy one array to another
b) To reverse an array
c) To sort an array
d) To find an element in an array

Answer 13

a) To copy one array to another

System.arraycopy() is used to copy elements from one array to another.

14. What is printed by the following code snippet?

public class Test {
    public static void main(String[] args) {
       int[] arr = new int[5];
      System.out.println(arr[1]);
    }
}

Choose one option

a) 0
b) null
c) undefined
d) Compilation error

Answer 14

a) 0

Integer arrays are initialized to 0 by default.

15. What will be the result of this program?

public class array_output {
    public static void main(String args[])
    {
        int[] arr = {1, 2, 3, 4};
        System.out.println(arr.length);
    }
}

Choose one option

a) 0
b) 3
c) 4
d) Compilation error

Answer 15

c) 4

arr.length returns the number of elements in the array, which is 4.

16.  What exception is thrown by Java code when trying to store values in a sufficiently large dimension of an array but with the wrong data type?

Choose one option

a) ArrayIndexOutOfBoundsException
b) IllegalArgumentException
c) ClassCastException
d) ArrayStoreException

Answer 16

d) ArrayStoreException

ArrayStoreException occurs when attempting to store incorrect types into arrays of object types.

17.  Which of the following is not a valid way to declare a two-dimensional array in Java?

Choose one option

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

Answer 17

d) int[][] arr = new int[][];

Option D is invalid because while it declares a two-dimensional array, it does not specify the size of either dimension at the time of declaration.

18. What is the correct way to iterate over a Java array using an enhanced for loop?

a) for (int i : arr)
b) for (int i = 0; i < arr.length; i++)
c) for (arr : int i)
d) for (arr i : int)

Answer 18

a) for (int i : arr)

The enhanced for loop in Java is written as for (type variable : array).

 19.  What will happen if you try to store a double value into an int array?

a) The value will be rounded
b) The value will be truncated
c) A ClassCastException will be thrown
d) A compile-time error

Answer 19

d) A compile-time error

You cannot store a double value in an int array without explicit casting, leading to a compile-time error.

20. What is the output of the following code?

public class array_output {
    public static void main(String args[])
    {
        int[] arr = {2, 4, 6, 8};
        System.out.println(arr[arr.length]);
    }
}

Choose one option

a) 8
b) 4
c) 0
d) ArrayIndexOutOfBoundsException

Answer 20

d) ArrayIndexOutOfBoundsException

Since array indices are 0-based, accessing arr[arr.length] is out of bounds. The valid indices for this array are from 0 to arr.length – 1.

21. What is the output of the following code?

public class array_output {
    public static void main(String args[]) {
        int[] arr = {1, 2, 3, 4, 5};
        for (int i = 0; i < arr.length; i++) {
            arr[i] = arr[i] * 2;
        }
        System.out.println(arr[2]);
    }
}

Choose one option

a) 3
b) 6
c) 8
d) 10

Answer 21

b) 6

The loop multiplies each element by 2. Therefore, arr[2] becomes 3 * 2 = 6.

22. What will be the output of the below program?

public class array_output {
    
    public static void main(String args[]) {
        int[] arr = {10, 20, 30, 40};
        System.out.println(arr[1] + arr[2]);
    }
}

Choose one option

a) 30
b) 50
c) 60
d) 70

Answer 22

b) 50

arr[1] is 20 and arr[2] is 30, so the sum is 20 + 30 = 50.

23. Can you resize an array in Java after it is created?

Choose one option

a) Yes
b) No

Answer 23

b) No

24. How can you access the element at the second row and third column of a two-dimensional array “matrix”?

a) matrix[3][2]
b) matrix[2, 3]
c) matrix[1][2]
d) matrix[2:3]

Answer 24

c) matrix[1][2]

Array indexing starts at 0 in Java, so the second row is index 1, and the third column is index 2.   

25. What will be the default value of the elements in a two-dimensional array of type `int[][]` in Java?

a) null
b) 0
c) undefined
d) Compilation error

Answer 25

b) 0

For arrays of primitive data types like int, the default value of the elements is 0.

We would love to hear from you! Please leave your comments and share your scores in the section below

vibssingh

Java – Multiple Choice Questions and Answers – Strings

Last Updated On

HOME

Welcome to the Java Quiz! This blog post features 25 multiple-choice questions that explore the concepts of Strings in Java.

1. What is the primary characteristic of strings in Java?

a) Mutable
b) Immutable
c) Dynamic
d) External

Answer 1

b) Immutable

Strings in Java are immutable, meaning their values cannot be changed once created.

2. What is the correct way to declare a String in Java?

a) String str = ‘Hello’;
b) String str = new String(“Hello”);
c) String str = String(“Hello”);
d) String str = Hello;

Answer 2

b) String str = new String(“Hello”);

Strings in Java are declared using String str = new String(“Hello”); or simply String str = “Hello”;.

3. What is the default value of an element in an int array in Java?

Choose one option

a) 1
b) 0
c) null
d) Undefined

Answer 3

b) 0

In Java, arrays of primitive types like int are initialized to their default values. The default value for int is 0

4. What will be the output of the following Java program?

class Test
    {
        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++;
            }
        } 
   }

Choose one option

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

Answer 4

a) 0 2 4 6 8

When an array is declared using new operator then all of its elements are initialized to 0 automatically. for loop body is executed 5 times as whenever controls comes in the loop i value is incremented twice, first by i++ in body of loop then by ++i in increment condition of for loop.

5. Why are Strings immutable in Java?

a) To improve performance
b) To allow modifications in-place
c) To ensure thread safety and security
d) Because Java does not support mutable objects

Answer 5

c) To ensure thread safety and security

String immutability ensures that once created, a String cannot be modified, making it thread-safe and secure.

6. What will be the output of the following Java program?

public class Test {
    
    public static void main(String args[]) {
        String obj = "I" + "like" + "Java";
        System.out.println(obj);
    }
}

Choose one option

a) I
b) like
c) Java
d) IlikeJava

Answer 6

d) IlikeJava

 Java defines an operator +, it is used to concatenate strings.

7. What will be the output of the following Java program?

public class Test {
    
    public static void main(String args[]) {
        String obj = "I LIKE JAVA";
        System.out.println(obj.charAt(3));
    }
}

Choose one option

a) I
b) L
c) K
d) E

Answer 7

a) I

charAt() is a method of class String which gives the character specified by the index. obj.charAt(3) gives 4th character

8. What will be the output of the following Java program?

public class Test {

    public static void main(String args[]) {
        String obj = "I LIKE JAVA";
        System.out.println(obj.length());
    }
}

Choose one option

a) 9
b) 10
c) 11
d) 12

Answer 8

c) 11

The string “I LIKE JAVA” contains 11 characters, including the spaces. The length() method returns the total number of characters in the string. So, the output is 11.

9. What will be the output of the following Java program?

public class Test {

    public static void main(String args[]) {
        String obj = "hello";
        String obj1 = "world";
        String obj2 = obj;
        obj2 = " world";
        System.out.println(obj + " " + obj2);
    }
}

a) hello hello
b) world world
c) hello world
d) world hello

Answer 9

c) hello world

This is the standard way of declaring an array of strings in Java.

10. Which of the following is a valid declaration and initialization of String array in Java

public class Test {

    public static void main(String args[]) {
        String obj = "hello";
        String obj1 = "world";
        String obj2 = "hello";
        System.out.println(obj.equals(obj1) + " " + obj.equals(obj2));
    }
}

a) false false
b) true true
b) true false
d) false true

Answer 10

d) false true

equals() is method of class String, it is used to check equality of two String objects, if they are equal, true is retuned else false.

11. What will be the output?

public class Test {

    public static void main(String args[]) {
        System.out.println("Hello World".indexOf('W'));
    }
}

Choose one option

a) 0
b) 5
c) 6
d) -1

Answer 11

c) 6

The indexOf() method returns the index of the first occurrence of the specified character.

12.   How do you compare two strings in Java?

Choose one option

a) ==
b) equals()
c) compareTo()
d) Both b) and c)

Answer 12

d) Both b) and c)

Use equals() for value comparison and compareTo() for lexicographical order.

13. Which of the following will return a substring from a string?

Choose one option

a) str.sub()
b) str.substring()
c) str.slice()
d) str.split()

Answer 13

b) str.substring()

The substring() method extracts a substring from the string.

14. What is printed by the following code snippet?

public class Test {

    public static void main(String args[]) {
        System.out.println("Java".compareTo("Java"));
    }
}

Choose one option

a) 0
b) 1
c) -1
d) Compilation error

Answer 14

a) 0

The compareTo() method returns 0 if the two strings are equal.

15. What will be the result of this expression?

public class Test {

    public static void main(String args[]) {
        System.out.println("abc".substring(1, 3));
    }
}

Choose one option

a) ab
b) abc
c) bc
d) a

Answer 15

c) bc

The substring(start, end) method returns the substring from start index to end-1.

16.  How can you check if a string is empty?

Choose one option

a) str.isEmpty()
b) str.length() == 0
c) Both a) and b)
d) str.equals(“”)

Answer 16

c) Both a) and b)

Both methods can be used to check if a string is empty.

17.  What does the StringBuilder class do?

Choose one option

a) It creates immutable strings.
b) It creates mutable strings.
c) It converts strings to numbers.
d) It is not a class in Java.

Answer 17

b) It creates mutable strings.

StringBuilder allows for the creation of mutable strings, which can be modified.

18. Which method would you use to split a string into an array based on a delimiter?

a) split()
b) divide()
c) slice()
d) substring()

Answer 18

a) split()

The split() method splits a string into an array based on a specified delimiter.

 19.  Which of the following will convert a string to a number?

a) parseInt()
b) valueOf()
c) toNumber()
d) Both a) and b)

Answer 19

d) Both a) and b)

Both parseInt() and valueOf() can convert a string to a number.

20. What is the output of the following code?

public class Test {

    public static void main(String args[]) {
        System.out.println("abc".repeat(3));
    }
}

Choose one option

a) abcabcabc
b) abc abc abc
c) abcabc abc
d) Compilation Error

Answer 20

a) abcabcabc

The repeat(int) method returns a string whose value is the concatenation of the specified string repeated the given number of times.

21. What is the output of the following code?

public class Test {

    public static void main(String args[]) {
        System.out.println("Hello".replace('e', 'a'));
    }
}

Choose one option

a) Hallo
b) Hello
c) Halla
d) Hella

Answer 21

a) Hallo

The replace() method replaces the specified character with another character.

22. What will be the output of the following program

public class Test {

    public static void main(String args[]) {
        String s1 = new String("Hello");
        String s2 = new String("Hello");
        System.out.println(s1 == s2);
    }
}

Choose one option

a) true
b) false
c) Compilation error
d) Runtime error

Answer 22

b) false

The == operator compares object references, not values. Since s1 and s2 are two different objects, it returns false.

23. Which of these methods can be used to check if two strings are equal, ignoring case considerations?

Choose one option

a) equals()
b) equalsIgnoreCase()
c) compareTo()
d) compareIgnoreCase()

Answer 23

b) equalsIgnoreCase()

The equalsIgnoreCase() method compares two strings, ignoring case differences.

24. What will be the result if you try to modify an existing string?

a) The string will be changed
b) A new string will be created
c) An exception will be thrown
d) Compilation error

Answer 24

b) A new string will be created

Strings in Java are immutable, so any modification creates a new string. 

25. Which method checks if a string starts with a specified prefix?

a) beginsWith()
b) start()
c) startsWith()
d) prefix()

Answer 25

c) startsWith()

The startsWith() method checks if the string begins with the specified prefix.

We would love to hear from you! Please leave your comments and share your scores in the section below

vibssingh

JAVA – Multiple Choice Questions and Answers

Last Updated On

HOME

Java – Multiple Choice Questions and Answers – Basic Java – NEW
Java – Multiple Choice Questions and Answers – Method, Overloading, Overriding – NEW
Java – Multiple Choice Questions and Answers – Exception Handling – NEW
Java – Multiple Choice Questions and Answers – Strings – NEW
Java – Multiple Choice Questions and Answers – Arrays – NEW
Java – Multiple Choice Questions and Answers – Inheritance & Polymorphism – NEW