Unit 9 Retake CSA

The process by which objects of one class acquire the properties of objects of another class is known as

• Polymorphism

• Inheritance

• Data Hiding

• Association

Output of following Java Program?

• 12

• 321

• 123

• 23

What is subclass in java?

• A subclass is a class that extends another class

• A subclass is a class declared inside a class

• Both above.

• None of the above.

Output of following Java program?

• Base

  Derived

  Derived

• Base

  Base

  Derived

• Base

  Derived

  Base

• Compiler Error

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

• super

• this

• extends

• extent

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

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{}

Class Cat extends Animal. Which is NOT a valid declaration?

• Cat x = new Cat();

• Animal X = new Animal();

• Cat x = new Animal();

• Animal x = new Cat();

When overloading a method, the method header ________ .

• Must exactly match the header of the method you are overloading.

• Must have the same name, but differ in order, number, or type of parameters.

• Can differ in name, but must have the same number and order of parameters.

• Can be completely different from the method you are overloading, but must have @Override.