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Java Interview Questions on Classes & Objects - 24

Question: 1

public class Main
{
private int a;
public Main(){
            a = -10;
        }
  
public static void main(String[] args) {
	Main obj = new Main();
 	System.out.println(obj.a);
	}
}

(A) 0
(B) Compilation Error
(C) -10
(D) Garbage Value

Level: Beginner Category of MCQ: classesAndobjects

Question: 2

public class Main
{
private int a;
public Main(){
        
    }
public Main(int temp){
        a = -10;
    }

public static void main(String[] args) {
    Main obj = new Main();
	System.out.println(obj.a);
}
}

(A) -10
(B) Undefined
(C) Compilation Error
(D) 0

Level: Practitioner Category of MCQ: classesAndobjects

Question: 3

public class Main
{
private int a;    

public Main(){
    a = 10;
}

public static void main(String[] args) {
    Main obj = new Main();
    obj.a = -10;
    System.out.println(obj.a);
}
}

(A) 0
(B) 10
(C) -10
(D) Compilation Error

Level: Beginner Category of MCQ: classesAndobjects

Question: 4

class cppbuzz{
    private void sum(){
        System.out.println("hi");
    }
}

public class Main
{
	public static void main(String[] args) {
		cppbuzz obj = new cppbuzz();
		obj.sum();
	}
}

(A) hi
(B) nothing is printed
(C) error: sum() has private access
(D) Exception

Level: Beginner Category of MCQ: classesAndobjects

Question: 5

class cppbuzz{
    protected void sum(){
        System.out.println("hi");
    }
}

public class Main
{
	public static void main(String[] args) {
		cppbuzz obj = new cppbuzz();
		obj.sum();
	}
}

(A) hi
(B) Compilation Error
(C) Nothing is printed
(D) Exception

Level: Beginner Category of MCQ: classesAndobjects

Question: 6

class cppbuzz{
    public static void sum(){
        System.out.println("hi");
    }
}
public class Main
{
	public static void main(String[] args) {
		cppbuzz obj = new cppbuzz();
		obj.sum();
	}
}

(A) hi
(B) Compilation Error
(C) Exception
(D) None of the above

Level: Beginner Category of MCQ: classesAndobjects

Question: 7

class cppbuzz{
    public static void sum(){
        System.out.println("hi");
    }
}
public class Main
{
	public static void main(String[] args) {
	    cppbuzz.sum();
	}
}

(A) hi
(B) Compilation Error
(C) Exception
(D) None of the above

Level: Beginner Category of MCQ: classesAndobjects

Question: 8

class cppbuzz{
    protected static void sum(){
        System.out.println("hi");
    }
}
public class Main
{
	public static void main(String[] args) {
	    cppbuzz.sum();
	}
}

(A) hi
(B) Compilation Error
(C) Exception
(D) None of the above

Level: Beginner Category of MCQ: classesAndobjects

Question: 9

class cppbuzz{
    private static void sum(){
        System.out.println("hi");
    }
}
public class Main
{
	public static void main(String[] args) {
	    cppbuzz.sum();
	}
}

(A) hi
(B) Compilation Error
(C) Exception
(D) None of the above

Level: Beginner Category of MCQ: classesAndobjects

Question: 10

class cppbuzz{
    static void sum(){
        System.out.println("hi");
    }
}
public class Main
{
	public static void main(String[] args) {
	    cppbuzz.sum();
	}
}

(A) error: sum() is private default
(B) hi
(C) Exception
(D) Nothing is printed

Level: Practitioner Category of MCQ: classesAndobjects

Question: 11

How does below code behaves?

public class Main
{
private static void main(String[] args) {
	    
	}
}

(A) Code runs but nothing is printed
(B) Code runs in infinite loop
(C) error: Main method not found
(D) Exception

Level: Expert Category of MCQ: classesAndobjects

Question: 12

How may main() methods are allowed in a project of Java?

(A) 1
(B) 2
(C) 3
(D) Max 256

Level: Beginner Category of MCQ: classesAndobjects

Question: 13

class ITCompanies{

    private void Capgemini(){
        System.out.print("Cap ");
    }
    private void Cognizant(){
        System.out.print("Cog ");
    }
    public void func(){
        Capgemini();
        Cognizant();
    }
    public ITCompanies(){
        func();
    }
}

public class Main
{
	public static void main(String[] args) {
	      ITCompanies javaObj = new ITCompanies();
	      javaObj.func();
	}
}

(A) Cap Cog
(B) Cap Cap
(C) Cog Cog
(D) Cap Cog Cap Cog

Level: Expert Category of MCQ: classesAndobjects

Question: 14

class ITCompanies{

    private void Capgemini(){
        System.out.print("Cap ");
    }
    private void Cognizant(){
        System.out.print("Cog ");
    }
    public void func(){
        Capgemini();
        Cognizant();
    }
    public ITCompanies(){
        func();
    }
}

public class Main
{
	public static void main(String[] args) {
	      ITCompanies javaObj = new ITCompanies();
	}
}

(A) Cap Cog
(B) Cap Cap
(C) Cog Cog
(D) Cap Cog Cap Cog

Level: Expert Category of MCQ: classesAndobjects

Question: 15

Can we call Constructor without creating an object ?

(A) Yes
(B) No

Level: Practitioner Category of MCQ: classesAndobjects

Question: 16

package com.google.test;

public class Abc {

	private int a = 10;
	int b = 20;
	protected int c = 30;
	public int d = 40;

	public void Abc() {
		System.out.print(a);
		System.out.print(b);
		System.out.print(c);
		System.out.print(d);
	}

	public void xyz() {
		System.out.println("Hello");
	}

	public static void main(String[] args) {
		Abc obj = new Abc();
		obj.xyz();
	}
}

(A) 10203040
(B) 10203040Hello
(C) Hello
(D) None of these

Level: Expert Category of MCQ: classesAndobjects

Question: 17

package com.google.test;

public class Abc {

private int a = 10;
int b = 20;
protected int c = 30;
public int d = 40;

public void Abc() {
System.out.print(a);
System.out.print(b);
System.out.print(c);
System.out.print(d);
}

public void xyz() {
System.out.println("Hello");
}

public static void main(String[] args) {
Abc obj = new Abc();
}
}

(A) 10203040
(B) 10203040Hello
(C) Hello
(D) Nothing is printed

Level: Expert Category of MCQ: classesAndobjects

Question: 18

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

(A) null
(B) Nothing is printed
(C) Exception
(D) Compilation Error

Level: Expert Category of MCQ: classesAndobjects

Question: 19

public class Main
{
System.out.print("Hello");
    
public static void main(String[] args) {
         
     }
}

(A) Hello
(B) Compilation Error
(C) Exception
(D) None of these

Level: Practitioner Category of MCQ: classesAndobjects

Question: 20

Enum is most useful in creating

(A) Singletons
(B) Java Beans
(C) Transactions
(D) None of the above

Level: Expert Category of MCQ: classesAndobjects

Question: 21

Which of the following reference types cannot be generic?

(A) Anonymous inner class
(B) Interface
(C) Inner class
(D) All of the mentioned

Level: Expert Category of MCQ: classesAndobjects

Question: 22

Find the output of below Java program:

public class Main
{
    public int a;
    
    public Main(int a){
        a = a;
        System.out.print(a);
    }
	public static void main(String[] args) {
		Main obj = new Main(5);
		System.out.print(obj.a);
	}
}

(A) 00
(B) 05
(C) 50
(D) 55

Level: Practitioner Category of MCQ: classesAndobjects

Question: 23

public class Main {
 int num = 100;
 
 public void calc(int num) {
 this.num = num * 10;
 }
 
 public void printNum(){
 System.out.println(num);
 }
 
 public static void main(String[] args) {
 Main obj = new Main ();
 obj.calc(2);
 obj.printNum();
 }
}

(A) 100
(B) 1000
(C) 2
(D) 20

Level: Practitioner Category of MCQ: classesAndobjects

Question: 24

public class Calculator {
 int num = 100;
 public void calc(int num) {
 this.num = num * 10;
 }
 public void printNum(){
 System.out.println(num);
 }
 public static void main(String[] args) {
 Calculator obj = new Calculator ();
 obj.calc(2);
 obj.printNum();
 }
}

(A) 100
(B) 1000
(C) 2
(D) 20

Level: Practitioner Category of MCQ: classesAndobjects

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Java Interview Questions on Classes & Objects - 24

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