ICSE CLASS 10 COMPUTER APPLICATION - Chapter 1: Concept of Objects

1.  Give two examples of real-world objects. Also specify their characteristics and behaviour.

Ans. Real Life Objects

Example1:

Object Name:   Pen

Characteristics: Company made, Colour, Body Shape and Nip.

Behaviour:

1)      Used for writing.

2)      Used for correction

3)      Used for drawing or sketching

Example 2:

Object Name:     Dog

Characteristics: Name, Colour and Breed.

Behaviour:

1)      Barking

2)      Wagging its tail

3)      Running speed

2.  What do you understand by state of an object? Explain with an example.

Ans. State of an object refers to the condition in which an object is in. Thus the values/attributes of its characteristics is represented For example, a book is an object, which may be either in “open” or “closed” state, similarly a bulb may be in switched on or switched off state.

3.  How are objects implemented in Software?

Ans. Every object in real life has certain characteristics and behavior. It is the characteristic that is represented by data variables and behaviour by methods or functions encapsulated in a class using a software.

4.  What is abstraction? How is encapsulation related to it?

Ans. Abstraction is the process of hiding the complexity and giving a simple interface and encapsulation is the process of implementing abstraction.

Using encapsulation, the data and the code is wrapped round inside a class.

5. Define encapsulation.                                                                                 [ICSE 2006]

Ans. Encapsulation is the process of wrapping/combining the characteristics and behavior into a single unit of an object to form a unique identit.

6. Explain the term object using an example. [ICSE 2006] Ans. An object is an entity with certain characteristics and behaviour making it having its own individuality and distinguishable. For example a pen has certain characteristics, for example its colour, shape, size, etc. and behaviour which is used to write, sketch or draw, etc. Even though two pens are identical with the same colour, texture, shape and size, yet they are two distinguishable pens.

7.  What is a class?

Ans. A class is a method to implement encapsulation is programming. It is the class keyword in Java that is used to wrap around the data members and member methods into a single unit. It acts as a template that allows instances of it to be created, which are called objects.

8.  What is Message Passing?

Ans. When the objects need to interact with one another, they pass or request information to or from one another. This interaction is knows as message passing.

9.  What is Object-Oriented Programming?

Ans. Object Oriented Programming is a technique of implementing programs which are organized as a co-interactive collection of objects, each of which represents an instance of a class.

10. State the 4 characteristics/principles of Object-Oriented Programming.        [ICSE 2005]

Ans. The 4 characteristics/principles of Object Oriented Programming are:

i)                    Abstraction

ii)                  Encapsulation

iii)                Polymorphism

iv)                Inheritance

11.  Explain briefly:

a) Abstraction                                b) Inheritance             c) Polymorphism

Ans. a) Abstraction: Abstraction refers to the art of hiding the complexities and giving a simple interface. For example in a car, for a layman, it is good enough to know driving. Hardly will he know the intricacies of movement of the engine, the working of the electrical and electronic components; what he will know or will be interested with is the steering for turning, the accelerator for speed and the switches. This is because he has been given a simple interface and the complexity of the car engine movement has been kept completely hidden from him. Thus he doesn’t bother about the intricacies of the car’s engine movement, but concentrates only on driving.

b)   Inheritance: Inheritance is the ability to inherit characteristics from another object. In more concrete terms, an object is able to pass on its state and behaviours to its children. For inheritance to work, the objects need to have characteristics in common with each other. It is basically a term that is used to represent hierarchical relationship of generalization.

c)  Polymorphism: The term Polymorphism is actually a combination of two terms

Poly and Morphism. Here the term Poly means many and Morphism means forms. It is the ability of objects to have many methods of the same name, but each one responds to different types of specific behaviour as they have different forms.

12.  How does class acts as a blueprint for an object?

Ans. A class acts as a blueprint or template that defines certain characteristics and behaviour and an object is an instance or copy of a class.

13.  How does encapsulation acts as a protective layer for an object?

Ans. Encapsulation is a technique that binds together function and the data into a single unit. You can imagine it to be as a protective wrapper that prevents the code and data from being accessed by other codes defined outside the wrapper.

14.    How does modularity helps in reducing the complexity of a program? 

Ans. Modularity helps in breaking a huge task into smaller units called functions for easy maintainability and reusability thus reducing the complexity of the task at large.

15.  What do you understand by data abstraction? Explain with an example. [ICSE 2006 & 2010] Ans. Data abstraction refers to, providing only essential information to the outside world and hiding their background details, i.e., to represent the needed information in program without presenting the data.

Let's take one real life example of a TV, which you can turn on and off, change the channel, adjust the volume, and add external components such as speakers, VCRs, and DVD players, BUT you do not know its internal details, that is, you do not know how it receives signals over the air or through a cable, how it translates them, and finally displays them on the screen.

16.  Give a real world explanation about abstraction.

Ans. A switch board is an example of abstraction. Imagine if the concept of switchboard did not exist. You would find a great number of wires hanging round your room. To start with an appliance, you needed to join two wires. But essentially you need to know which group of wires should be joined to start an appliance. Moreover, more the number of wires, more will it be confusing to identify the wires to start an appliance. Thus joining of wires is not only confusing but may also prove fatal as far as safety is concerned. Thus, the electrician installs a switchboard that connects each of the wires to a switch. Hence, it is just enough to know for the user to switch on that switch that starts an appliance.

17.  Why is abstraction often referred to be as relative?

Ans. Abstraction is often referred to as relative because abstraction is the selective examination of certain aspects of a problem. The goal of abstraction is to isolate those aspects that are important for some purpose and suppress or hide those aspects that are unimportant. Abstraction must always be for some purpose, because the purpose determines what is important and what is not. Many different abstractions of the same thing are possible, depending on the purpose for which they are made.