Introduction To Java



History

Java is an object-oriented programming language. Java was developed by James Gosling and colleagues at Sun Microsystems in the year 1990. Java was started as a project called "Oak" by James Gosling in June 1991. Java is the most popular language. Java is used for programming, games, mobile devices, etc Java is used. The Java team members(also known as Green Team).

Introduction To Java

Java is a programming language. Java released by Sun Microsystems in the year 1995.There are many website, application are work on java. Java is free and open source. Java is object-oriented programming language. It is plateform Independent. Java is the most popular language and highly used programming language. It is simple and easy to learn and use.

Java is :- 
- Object-Oriented
- Simple
- Plateform Independent
- Portable
- Dynamic
- Secure

Editor For Java

To Write Java program there are lot of editor where you can write and run java program. The basic java editor are :
1) Notepad
2) Netbeans
3) Eclipse

Java is the highly used programming language in the modern world most desktop, android application, websites, etc. are used java programming.

Java Bytecode

Java programs are written in the Java language and are compiled into Java bytecode which can be executed by the Java Virtual Machine(JVM).

The java Bytecode are stored in .class file.

Java Virtual Machine(JVM)

The Java language is compiled into Java bytecode. This Java bytecode is  executed by the Java Virtual Machine(JVM).

The JVM is like a computer. 

The JVM is implemented for the several different operating systems, like Windows, Mac OS, Linux, IBM mainframes, etc. Thus, the Java program can run on a Java Virtual Machine on Windows. Sun referred to this as "Write once, run anywhere".


Java Runtime Environment(JRE)

The Java Runtime Environment (JRE) is the Java Virtual Machine. The JRE contains enough to execute a Java application, but not to compile it.

Java Software Development Kit(Java SDK)

The Java Software Development Kit (Java SDK) is the JRE plus the Java compiler, and also a set of another tools.

If you think you need to develop a Java programs you must have to need the Java SDK. The JRE is not efficient. Only the Java SDK contains the Java compiler which convert your .java source files into byte code .class files.

Java Enterprise Edition(JEE)

Java Enterprise Edition contains a many of extra tools and APIs for executing Java components inside a Java Enterprise Server. Examples of enterprise Java components are:

1) Servlets
2) Java Server Pages (JSP)
3) Java Server Faces (JSF)
4) Enterprise Java Beans (EJB)
5) Two-phase commit transactions
6) Etc.


When we write a java program, the following things must include are :

1) Object

2) Class

3) Method

4) Instance Variable

Basic Syntax Of Java

The basic structure of java program are as follow :

Public class class_Name{  // This is Class Name
    public function_Name{
                                // This is Function (if required)
      }
    
   public static void main(String args[])
  {
      // This is Main Method
  }
  
} // End of class

Note : In java program there are multiple classes but only have on main method.

Simple Hello World Program In Java

public class HelloWorld{

   public static void main(String args[])
    {
        System.out.println(" Hello World ");
    }
 
}


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