INTRODUCTION II

Question 1

Define programming

Answer 1

Programming is the process of creating a set of instructions that tell a computer how to perform a task

Question 2

What are the advantages of inheritance

Answer 2

Promotes reusability
Code is reliable since it has already been tested and debugged
Effort and time is saved

Question 3

What are the advantages of encapsulation

Answer 3

• Encapsulation protects an object from unwanted access by clients.
• Encapsulation allows access to a level without revealing the complex details below that level.
• It reduces human errors.
• Simplifies the maintenance of the application
• Makes the application easier to understand.

Question 4

What are the advantages of polymorphism

Answer 4

It helps the programmer to reuse the codes, i.e., classes once written, tested and implemented can be reused as required. Saves a lot of time.

Single variable can be used to store multiple data types.

Easy to debug the codes.

Question 5

What are the advantages of abstraction

Answer 5

Encapsulation protects an object from unwanted access by clients.
Encapsulation allows access to a level without revealing the complex details below that level.
It reduces human errors.
Simplifies the maintenance of the application
Makes the application easier to understand.

Question 6

Explain the difference between encapsulation and data abstraction as used in object oriented programming

Answer 6

Abstraction- Problems are solved at the design level
Encapsulation- Problems are solved at the implementation level

In abstraction, implementation complexities are hidden using abstract classes and interfaces. While in encapsulation, the data is hidden using methods of getters and setters.

Question 7

Explain the difference between polymorphism and inheritance as used in object-oriented programming

Answer 7

Inheritance is basically applied to classes. Whereas polymorphism is basically applied to functions or methods.

Question 8

Briefly explain any two different types of inheritance supported in OOP

Answer 8

1. Single-When a class extends another one class only then we call it a single inheritance.
2. Multiple Inheritance- one class extending (Or inherits) more than one base class.
3. Multilevel inheritance -one can inherit from a derived class, thereby making this derived class the base class for the new class.
4. Heirachical -one class is inherited by many sub classes
5. Hybrid inheritance is a combination of Single and Multiple inheritance.

Question 9

Briefly explain the different programming paradigms

Answer 9

Imperative: Programming with an explicit sequence of commands that update state.
Declarative: Programming by specifying the result you want, not how to get it.
Structured: Programming with clean, goto-free, nested control structures.
Procedural: Imperative programming with procedure calls.

Question 10

what are constructors in java?

Answer 10

A Java constructor is special method that is called when an object is instantiated. In other words, when you use the new keyword. The purpose of a Java constructor is to initializes the newly created object before it is used

Question 11

Code excerpt of polymorphism

Answer 11

public class Animal{
   ...
   public void sound(){
      System.out.println("Animal is making a sound");   
   }
}

public class Horse extends Animal{
...
    @Override
    public void sound(){
        System.out.println("Neigh");
    }
}

Question 12

Code excerpt of abstraction

Answer 12

abstract class Shape{
	// code
}

public class Sports implements Shape

[
]

Question 13

Code excerpt of encapsulation

Answer 13

class Account {
    private int account_number;
    private int account_balance;

    public void show Data() {
        //code to show data 
    }

    public void deposit(int a) {
        if (a < 0) {
            //show error 
        } else
            account_balance = account_balance + a;
    }
}

Question 14

Using a code segment (s), explain the usage of keyword super in Java programming.

Answer 14

The super keyword refers to superclass (parent) objects. It is used to call superclass methods, and to access the superclass constructor. The most common use of the super keyword is to eliminate the confusion between superclasses and subclasses that have methods with the same name.

class Vehicle
{
    int maxSpeed = 120;
}

/* sub class Car extending vehicle */
class Car extends Vehicle
{
    int maxSpeed = 180;

    void display()
    {
        /* print maxSpeed of base class (vehicle) */
        System.out.println("Maximum Speed: " + super.maxSpeed);
    }
}

/* Driver program to test */
class Test
{
    public static void main(String[] args)
    {
        Car small = new Car();
        small.display();
    }
}

Question 15

Explain the difference between throw and throws as used in OOP

Answer 15

1. Point of Usage
   The throw keyword is used inside a function. It is used when it is required to throw an Exception logically. The throws keyword is used in the function signature. It is used when the function has some statements that can lead to exceptions.
2. Exceptions Thrown
   The throw keyword is used to throw an exception explicitly. It can throw only one exception at a time. The throws keyword can be used to declare multiple exceptions, separated by a comma. Whichever exception occurs, if matched with the declared ones, is thrown automatically then.
3. Syntax
   Syntax of throw keyword includes the instance of the Exception to be thrown. Syntax wise throw keyword is followed by the instance variable. throw new ArithmeticException(“/ by zero”); Syntax of throws keyword includes the class names of the Exceptions to be thrown. Syntax wise throws keyword is followed by exception class names. public static void main(String[] args)throws InterruptedException