Introductions of Java programming language

 Over view of java:

• Java was invented by James Gosling at Sun Microsystems, Inc in 1991.
• It took 18 months to develop the 1^st versions of java.
• This language is initially called “Oak” but was renamed “Java” in 1995.
• Java has become the most important programming language because it is a language for the internet.

Features in Java:

• It is a very simple programming language.
• Java is a popular language because it is Object Oriented Programming language like C++.
• Platform independence (It can be executed on a variety of systems so write once, run anywhere, and at any time, forever).
• Java supports multithreading programming which allows a programmer to write such a program that can perform many tasks simultaneously.
• Java is designed for distributed systems. Hence two different objects on a different computer can communicate with each other. This can be achieved by remote Method Invocation (RMI). This feature is very much useful in client-server communication.

Types of Java:

• JAVA2SE - Standard Edition - This provides basics and for the desktop application. 
• JAVA2EE - Enterprise Edition -This is for web application development.  
• JAVA2ME - Micro Edition -This is to develop the application for mobile, tablet.ect.

Java Programs

Java programs fall into two categories:

1.     Applications

2.     Applets

Applications:

An application in java is a program that you can execute from any operating system prompt.

Stand-alone applications can either be,

1.     Window-based applications

2.     Console based applications

Applets:

Applets are programs that execute inside a web page.

Applications of java:

• Desktop GUI Applications
• Mobile Applications
• Scientific Applications
• Web-based Applications
• Big Data Technologies
• Distributed Applications
• Cloud-based Applications
• Web servers
• Software Tools
• Gaming Applications

Working in an environment of java:

Download net beans with JDK, click the below link to download.

https://www.oracle.com/technetwork/java/javase/downloads/jdk-netbeans-jsp-3413139-esa.html

Basic structure of Java:

Syntax of java:

1. package package_name; // Optional part

   import package_names;//Optional part

   class class_name

   {

   main method()

   {

   //variable declaration

   //Method declaration

   }

   }

Example program:

1. // Write a program to add two number and value get from user.

   package exampleprogram;

   import java.util.Scanner;

   public class Exampleprogram {

       public static void main(String[] args) {

          Scanner input = new Scanner(System.in);

          int a,b;

          System.out.println("Enter two value  : ");

          a = input.nextInt();

          b = input.nextInt();

          int c=a+b;

          System.out.println("Additions of a and b value is : "+c);

       }

   }

Output:

Program Explanation:

// Write a program to add two numbers... – This is a command-line for human understanding and not be executed in output.

Package – It is used to hold a number of classes.

Import – It is used to calling the external packages.

java.util.Scanner – This package is used to calling the scanner function(To get values from the user).

public class Exampleprogram: class definition part

• public – it is access specifiers and it can be used anywhere.
• Class – it is a keyword.
• Exampleprogram – class name
• Class is used to bind the variables and methods.

public static void main(String[] args): Mani method

• public - it is access specifiers from anywhere we can access it.
• static - it is an access modifier we can call the methods directly by class name without creating its objects.
• void - it is the return type of your output.
• main() - it is a standard method name and used to indicate starting your program here to the compiler.
• String [] args - in java accept only the string type of argument and store it.

Scanner – It is used to get value from users.

input – It is an object name for scanner and this is a user-defined name.

int a,b – variable declaration part

• int – it is a data type i.e. declaring kinds of your data format.
• a,b -  variable i.e. used to hold the values.

System.out.println – Print function.

• It is used to display any sentence on the user's system.

nextInt() – It is a method for integer data types and gets values from users.

Execution process of java:

Backend process of java when executing the program:

Step 1: Source code – your program

Step 2: Code editor

• It is used to edit the programs.

Step 3: Compiler

• It is used to check errors.
• If your program has an error then go to step 2 to solve an error.

Step 4: Byte code convertor

• If no error in your program then it’s converted to byte code that means machine code (0’s and 1’s).

Step 5: JVM (Java Virtual Machine)

• JVM is nothing but, it is your platform like a laptop, phone, computer, etc.
• It is used to execute the byte codes.

Step 6: JIT (Just In Time compiler)

• It is used to convert byte code into running machine code i.e. English language.

Step 7: Output

• The final result is displaying in your systems.

Note:

If you need to learn about what is a programming language? then click the below link to learn.

 https://www.whereisstuff.com/2020/09/introductions-of-programming-language.html

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