Java Classes and Objects

Here are 10 essential multiple-choice questions on Java Classes and Objects, covering key concepts.

Last Updated : Mar 27, 2025

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Question 1

Which of the following is NOT an OOP concept in Java?

A
Encapsulation
B
Inheritance
C
Polymorphism
D
Compilation

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Question 2

What is an object in Java?

A
A class template
B
An instance of a class
C
A function
D
A primitive data type

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Question 3

What is the primary purpose of a constructor in Java?

A
To allocate memory
B
To initialize an object
C
To call methods
D
To delete objects

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Question 4

Which keyword is used to create an object in Java?

A
class
B
this
C
new
D
void

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Question 5

What will be the output of the following code?

Java

class Test {
    int x;
}
public class Main {
    public static void main(String[] args) {
        Test t = new Test();
        System.out.println(t.x);
    }
}

A
0
B
null
C
Compilation Error
D
Runtime Exception

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Question 6

What is encapsulation in Java?

A
Wrapping data and methods into a single unit
B
Allowing multiple forms of a method
C
Inheriting properties from a parent class
D
Overriding methods from an interface

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Question 7

What will be the output of the following code?

Java

class Car {
    String model;
}
public class Main {
    public static void main(String[] args) {
        Car c = null;
        System.out.println(c.model);
    }
}

A
null
B
Compilation Error
C
NullPointerException
D
Empty String

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Question 8

Which of the following is TRUE about constructors?

A
Constructors must always have a return type
B
Constructors cannot be overloaded
C
Constructors can have parameters
D
A class cannot have multiple constructors

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Question 9

What will be the output of the following code?

Java

class Example {
    Example() {
        System.out.println("Constructor called");
    }
}
public class Main {
    public static void main(String[] args) {
        Example e = new Example();
    }
}

A
Constructor called
B
No output
C
Compilation Error
D
Runtime Error

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Question 10

What is the correct way to define a class in Java?

A
public Example {}
B
class Example {}
C
void Example {}
D
object Example {}

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