CBSE Class 12 Informatics Practices Concept Of Inheritance In Java

UNSOLVED QUESTIONS

1. What are the different types of access specifier supported by java?

2. Which is the default package of java?

3. What is friendly access of class member?

4. How does a class enforce information hiding?

5. Define an abstract class and abstract methods.

6. What is an interface? What is the use of Interface.

CONCEPT OF INHERITANCE IN JAVA

Solved Questions:

1. What is inheritance ?

Ans: Inheritance is a form of software reusability in which new classes are created from existing classes by absorbing their attributes and behaviours.

2. What is the primary purpose of inheritance ?

Ans: The primary purpose of inheritance is code reusability.

3. Name three basic concepts in Java which are used in Object oriented programming.

Ans:The three basic concepts are Classes , Objects and inheritance.

4. Which constructor is called first: subclass or superclass ?

Ans: A subclass constructor always calls the constructor for its superclass first explicitly or implicitly to create and initialize the subclass members.

5. What is abstract class?

Ans:An Abstract class is the one that simply represents a concept and whose objects can’t be created. It is created through the use of keyword abstract. The superclass set up as an abstract class does not allow objects of its prototype to be created. In this case only objects of the subclass are used.

6. What is method overriding in Java?

Ans:A method in a subclass hides or overshadows a method inherited from the superclass if both methods have same signature.(i.e. the same name, number and type of arguments and the same return type.) This property is known as Overriding the Inherited method.

7. What is an Interface in Java?

Ans: An Interface defines a protocol of behaviour or it is a collection of constants and abstract methods. These are not classes, but they can be used in the definition of a class.

8. What is the significance of abstract class in Java program?

Ans: When a class defines a method using the same namem return type, and arguments as a method in its superclass, the method in the class overrides the method in the superclass. When the method is invoked for an object of the class, it is the new definition of the method that is called, and not the method definition from superclass. Methods may be overridden to be more public, not more private.

9. What types of inheritance does Java have?

Ans: Java supports only these inheritance types:

i. Single inheritance ii. Multilevel inheritance iii. Hierarchical

10. State True and False

a. A subclass inherits both member variables and member methods of superclass.

b. A class created with keyword abstract can have at the most one object.

c. Overloading and Overriding are similar concepts in Java.

d. Java supports single inheritance only at multiple levels of inheritance.

e. Interfaces are used for multiple inheritance.

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