Unit 9 CSA

Which of this keyword must be used to inherit a class?

• super

• this

• extends

• extent

class A

{

int i;

void display()

{

System.out.println(i);

}

}

class B extends A

{

int j;

void display()

{

System.out.println(j);

}

}

class inheritance_demo

{

public static void main(String args[])

{

B obj = new B();

obj.i=1;

obj.j=2;

obj.display();

}

}

• 0

• 1

• 2

• Compilation Error

What will be the output of the following Java program?

class A

{

int i;

}

class B extends A

{

int j;

void display()

{

super.i = j + 1;

System.out.println(j + " " + i);

}

}

class inheritance

{

public static void main(String args[])

{

B obj = new B();

obj.i=1;

obj.j=2;

obj.display();

}

}

• 2 2

• 3 3

• 2 3

• 3 2

In order to restrict a variable of a class from inheriting to subclass, how variable should be declared?

• Protected

• Private

• Public

• Static

If super class and subclass have same variable name, which keyword should be used to use super class?

• super

• this

• upper

• classname

If class B is subclassed from class A then which is the correct syntax

• class B:A{}

• class B extends A{}

• class B extends class A{}

• class B implements A{}

What does polymorphism mean?

• Changing shapes
• Having many forms
• Being unchangeable
• Easy

A class that is inherited is called a ______ .

• superclass

• Subclass

• subsetclass

• Relativeclass

The following Syntax is used for?

class Subclass-name extends Superclass-name

{

//methods and fields

}

• Polymorphism

• Encapsulation

• Inheritance

• None of the above

What is the output of the following Java program?

class A

{

int i = 5;

}

class B extends A

{

int j = 10;

void display()

{

System.out.println(i + " " + j);

}

}

class inheritance_test

{

public static void main(String args[])

{

B obj = new B();

obj.display();

}

}

• Compilation Error

• 0 0

• 10 5

• 5 10