Quiz on Java Classes and Objects

What will be the value of x printed?

1. class MyExample {

int x = 10;

}

public static void main ( String args [] )

{

MyExample object = new MyExample;

object.x = 15;

system.out.println(x);

}

What will be the output of the program?

class Sample {

string name;

int number;

} 

public static void main ( String args [] ) {

Sample object = new Sample;

object.name(“DataFlair”);

object.number();

system.out.println( name +  “ “ + “ , “ + number );

}

}

What is the error in the program?

class Demo {

}

demo ( String name) {

void display()

{

system.out.println(name);

}

}

public static void main ( String args [] )

{

Demo object = new Demo;

object.display();

}

What will be the output of the program?

 public static void add(int a , int b , int sum)

{

sum = a + b ;

}

public static void main ( String args [] )

{

int a = 1;

int b = 2;

int sum ;

add(a,b);

system.out .println(“ Sum is “ + sum );

}

These are two separate files saved with .java extension. Which file has to be executed to display the output?

Class First {

String name = “DataFlair”;

Int branches = 3;

Void display ( ) {

system.out.println(“Company name is “ + name + “ and it has “ + branches + “ branches “);

}

Public static void main ( String args [] ) {

First object = new First;

object.display();

}

Which of the following is the syntax for abstract classes in Java?

Which of the following is a mutable class in Java?

Which of the following is true about Static classes in Java?

From the program given below select the type of class it exhibits?

Class Organisms {

     String human;

     Class Humans {

           system.out.println(“We are Humans”);

}

}

This program exhibits sum and product calculation. All the methods are implemented and this can also be instantiated. What type of class is this?

 class Main {

    static int product(int a, int b)

    {

        return a * b;

    }

    static int sum(int a, int b)

    {

        return a + b;

    }

    public static void main(String args[])

    {

        int p = product(5, 10);

        int s = sum(5, 10);

        System.out.println(“Product: ” + p);

        System.out.println(“Sum: ” + s);

    }

}

Where the variable data should  be declared in a non static class?

class Outer{  

 class Inner

{  

 void msg() {

System.out.println(“data is “+data); 

}  

 }  

 public static void main(String args[]){  

  Outer obj=new TestMemberOuter1();  

  Outer.Inner in=obj.new Inner();  

  in.msg();  

 }  

}  

Which of the following is not a rule for writing singleton classes?

The given program is an example program for inheritance. Object should be created for which class to invoke both the methods?

Class organisms {

String Human = “people” , animals = “ Lion “;

Void display () {

system.out.println( Human + animals );

}

}

Class animals extends organisms {

Void display2() {

system.out.println(“The king of jungle is “ + animals );

}

}

Class Main {

Public static void main ( String args [] )

{

}

}

What will be the output of the given program?

public class Sample

{

}

public class Main

{

  public static void main(String[] args)

  {

    System.out.println(“DataFlair”);

  }

}

What will be the output of the program?

 class DataFlair

{ 

int branches; 

 }

class Main

{

  public static void main( String  args [ ]   )

  {

    DataFlair b = new DataFlair();

    b.branches = 30;

    DataFlair b2 = b;

    b = null;

    System.out.println(” No. of branches =” + b.branches);

  }

}