Q. a) State the difference between token and identifier, variable.
Ans. A token is the smallest individual unit in a program for e.g.:
Keyword, Identifiers, Literals etc. where as an identifier is the name given to
different parts of a program e.g. variable, functions, classes etc.
Variable: A memory location that stores a value is known as
variable. E.g. int a;
b) What is variable. Give an example.
Ans. Place holder of data in computer memory. E.g. Int a,b,c;
Q.
Define Byte code and JVM.
Ans. Byte code is the
compiled format for Java programs. Once a Java program has been converted to
byte code, it can be transferred across a network and executed by Java Virtual
Machine (JVM). Byte code files generally have a .class extension
Ans: JVM is a
platform-independent execution environment that converts Java byte code into
machine language and executes it. Most programming languages compile source
code directly into machine code that is designed to run on a specific
microprocessor architecture or operating system, such as Windows or UNIX. A JVM
-- a machine within a machine -- mimics a real Java processor, enabling Java
byte code to be executed as actions or operating system calls on any processor
regardless of the operating system.
Q.
Example the term Object and Class using an example.
Ans. Object: An instance of a class called Object. Table is an
instance of class Furniture.
Class: Blue print of an object
is called Class. Example, mango, apple and orange are members of the class
fruit.
Q. Name
four OOP’S principles.
Ans. Abstraction, Encapsulation, Polymorphism, Inheritance
Abstraction:
Abstraction refers to the act of representating essential features without
including the background details or explanations.
Encapsulation:
The wrapping up of data and methods into a single unit is called Encapsulation.
Polymorphism: polymorphism refers to a
programming language's ability to process objects differently depending on
their data type or class. More specifically, it is the ability to redefine
methods for derived classes. For example, given a base class shape,
polymorphism enables the programmer to define different area methods for any
number of derived classes, such as circles, rectangles and triangles. No matter
what shape an object is, applying the area method to it will return the correct
results.
Inheritance: Inheritance is the process by which objects of one class acquire the
properties of objects of anther class. Different kinds of objects often
have a certain amount in common with each other. Mountain bikes, road bikes,
and tandem bikes, for example, all share the characteristics of bicycles
(current speed, current pedal cadence, current gear). Yet each also defines
additional features that make them different: tandem bicycles have two seats
and two sets of handlebars; road bikes have drop handlebars; some mountain
bikes have an additional chain ring, giving them a lower gear ratio.
Q. Mention any two
attributes required for class declaration.
Ans: Variables and function or state and behaviour.
Q. Differentiate between base and derived class.
The base class is a class whose properties will be inherited and
the derived class is a class which inherits the base class. E.g. Of base class
is Super and derived class is sub.
Q. What is data types?
A data
type in a programming language is a set of data with values having predefined
characteristics. Examples of data types are: int, float,char etc.
The following chart
summarizes the default values for the above data types.
Data Type
|
Default Value (for fields)
|
byte
|
0
|
short
|
0
|
int
|
0
|
long
|
0L
|
float
|
0.0f
|
double
|
0.0d
|
char
|
'\u0000'
|
String
(or any object)
|
null
|
boolean
|
false
|
