Class as the Basis of All Computation

Chapter : Class as the Basis of All Computation

About Java Programming Language

Topics Covered

• Java: An Introduction
• Java Virtual Machine
  
• Class Libraries
  
• Java Character Set
• Tokens
• Keywords
• Identifiers
• Naming Convention of an Identifier
  
• Literals and its types
  
• Concepts of Data Types
• Variables
• Reference Types
• Constants
• Operators in Java
• Expressions
• Java Statements
• Significance of Classes
  

 JAVA : AN INTRODUCTION

                             Java was first developed by James Gosling at Sun Micro systems. It was released in May 1995 as a core component of Sun Micro systems '. Java was basically designed for electrical and electronic appliances for the operation of it remove and touch screen and finally it was found that Java can be used as a Programming language. It is divided into two types of programming

1. Java Applications
2. Java Applets
   

 The original and reference implementation Java compilers, virtual machines, and class libraries were originally released by Sun under proprietary licenses.

Java compilers: - Compiler is a program used to compile and run Java program.

Java Virtual Machine:-  A Java virtual machine is a virtual machine that enables a computer to run Java programs as well as programs written in other languages that are also compiled to Java byte code. The J.V.M is detailed by a specification that formally describes what is required in a J.V.M.

Class libraries: - The Java Class Library is a set of dynamically loadable libraries that Java Virtual Machine languages can call at run time. Because the Java Platform is not dependent on a specific operating system, applications cannot rely on any of the platform-native libraries.

Tokens:-The Java compiler breaks the line of code into text (words) is called Java tokens. These are the smallest element of the Java program.

Keywords:- These are the reserve words used for writing Java code.

Identifiers:- Identifiers are the name given to different parts of the program.   

Naming conventions Identifiers :-

1. No Identifier (variable / array / method / class) name should starts with a java keyword.

2. There is no space between an identifiers name.

3. No special characters(such as !@#$%^&*) except _ and $.

4. No identifier should starts with a digit.

Literals and its types:- The physical value which is stored or assign in a variable are literals.

Integer Literal (23,44.44)- The integer values are integer literals 

Integer Literal of three types

• Decimal (base 10)
• Octal (base 8)
• Hexadecimal (base 16)
  

Character Literal (A, B, a, b) - The character values are character literals

Floating Literals (23.43) - The small decimal values are float literals. Floating literal are also called Real literal.

Following are the

Double Literals (23.6889897) - The long decimal values are double literals

Boolean Literals (true,false) - The true-false values are boolean literals

Long Literals (38328236889897) - The long integer  values are Long literals

Shot Literals (45) - The shot integer  values are shot literals

Byte Literals (3) - The byte integer  values are byte literals

 

Concepts of Data Types

Sizes and values that can be stored in the variable can be specifies through data types. 

There are two types of data types in Java:

 1. Primitive data types: The primitive data types include

• int   it helps to define integer data(2, 3, 4, -1, -4, -7 etc).           Ex int x=10;
  
• char it helps to define character data(a, b, %, @, %, * etc).
• float (23.43F, 3.33F etc).
  
• short(22, 34, 44)
• long(38829239392398L, 39990284884998949L)
  
• boolean(true, false)
  
• byte(3, 4, 4, 3 etc)

 2. Non-primitive data types: The non-primitive data types include Classes, Interface and Array.

             Class : A prototype definition having data member and member methods.

            Array: A collection set of similar values of same type.

           Interfaces: A collection of classes.

 

Reference Types

 

Constants

 

Operators in Java

 

Expressions

 

Java Statements

 

Significance of Classes