Introduction to Java Programming

Java.....

 A simple language. But it is used in world wide because of its features.

 Yes. It is versatile and portable. It is famous by its robustness.

Who developed Java??

Java is developed by James Gosling at Sun Microsystems at 1991.

What is java?

Java is a high level  and Object Oriented Language. It has JVM(Java Virtual Machine) which is a unique feature in java.

What is JVM?

It is the run time environment which is used to execute the java byte codes. It has following steps.

·       First, the class files are loaded into JVM.

·       Next, it checks the byte codes whether it meets the java constraints.

·       If the constraints met, interpreter executes the code line by line.

·       Finally, Just In Time compiler converts the byte code to machine code.

·       Garbage collector frees the memory.

Java Editions:

Java editions can be classified into three types.

·       JSE(Java Standard Edition)- It develops Desktop applications

·       JEE(Java Enterprise Edition) – It develops Large scale, distributed applications.

·       JME(Java Micro Edition) – It develops applications for small devices like mobile phones.

Basic structure of Java Program:

Basic structure of java program contains a class associated with a main function.

Syntax:

class class_name

{

 public static void main(String args{})

{

 Statements………..

}

}

Let us quote with an example.

class first

{

public static void main(String args[])

{

 System.out.println(“Welcome to Java coding”)

}

}

First, compile this program.

>javac first.java

It converts your java file to class file.

Next, run the class file.

>java first

It shows the output

What are the variables?

              Variables are containers which is used to store the data. To Declare a variable, follow this syntax.

Datatype variable_name;

Eg:

int a;

String b;

To initialize a variable, assign a value to the variable.

Eg:

a = 10;

b = “Sample”;

 This is a simple introduction about java Programming.

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