Java Programing laungage

Core Java Tutorial

Introduction of Core Java

How To Install JDk and Set of Path

Syntax of java Program

Difference between Java and C/C++

Advantage and Disadvantage of Java

What is Java

Why Java is not Pure Object Oriented Language

Java has Following Features/Characteristics

Limitation of Java Language and Java Internet

Common Misconception about Java

Simple Program of Java

Integrated Development Environment in java

Compile and Run Java Program

Applet and Comments in Java

Tokens in Java

Keywords in Java

Identifier and Variables in Java

Literals/Constants

Data Type in Java

Assignments and Initialization in Java

Operators in Java

Rule of Precedence in Java

Operator on Integer and Separators in Java Programming

Java Control Flow of Statements

If and If-else Selection Statement

Nested If-else and If-else-If Selection Statement

switch case and conditional operator Selection Statement

for and while Loop

do..while and for each Loop

break and labeled break statement

continue and labeled continue statement

return Statement and exit() Method

Escape Sequence for Special Characters and Unicode Code

Constants and Block or Scope

Statement in Java

Conversions between Numeric Types in Java

Import Statement in Java

User Input in Java using Scanner Class

User Input in Java using Console Class

Array in Java

One Dimensional Array

Two Dimensional Array

Two Dimensional Array Program

Command Line Argument in Java

String args Types in Java

Uneven/Jagged array in java

Math Class Function and Constant

Math Class all Function used in a program

Enumerated Types in Java

Object Oriented Programming v/s Procedural Programming

Object Oriented Programming Concepts in Java

Introduction to Class,Object and Method in Java

Class Declaration in Java

Class & Objects in java

Encapsulation in Java

Modifiers/Visibility for a Class or Interrface or member of a Class

Polymorphism in Java

Runtime polymorphism (dynamic binding or method overriding)

Simple Program of Java
Previous Home Next
/*
This is a sample java program 
Save this file as Hello.java

*/

class Hello
{         //  A java program will start from here.
	public static void main(String args[])
	{
		System.out.println("Hello Delhi ");
	}}

output :

Hello Delhi

Suppose if you are write your program in notepad, then save this file as Hello.java

Compiling the program:After we have written our program we need to compile and run the program. For that we need to use the compiler called javac which is provided by java. Go to the command prompt and type the file name.

c:\>javac Hello.java

 

The javac compiler will create a class file called Hello.class that contains only bytecodes. These bytecodes have to be interpreted by a Java Virtual Machine(JVM) that will convert the bytecodes into machine codes. Once we successfully compiled the program, we need to run the program in order to get the output. So this can be done by the java interpreter called java.

c:\>java Hello

The output will be displayed as

Hello Delhi

Looking into the program line by line

/*This is a sample java program 
Save this file as Hello.java*/

This is called comment. This is for us to enter the comments about the program for our own convenience. The contents of a comment will be ignored by the compiler. Actually java supports three styles of comments. The above one is called multi-line comment which may contain several lines. This type of comment must begin with /* and end with */.

The next line of the code in a program is

class Welcome
{

The word class is a keyword to define a new class and Hello is a name of the class. The class definition must begins with opening curly brace ({) and ends with closing curly brace (}). The rest of the things defined inside these braces are called member of the class. And note that all the program activities are defined inside the class.

//  A java program will start from here.

This is another type of comment. This is called single line comment starts with // and ends with end of the line.

The next line of the code in a program is

public static void main(String args[])

This line begins with main method as like functions. The program will start execute by calling this main method. The keyword public is an access specifier. The keyword static is a kind of modifier. The keyword void means that the method main() does not return any value. As we had seen before all the java program will start execute by calling the main method. If we want to pass any information to a method will be received by the variables declared within the parenthesis is called parameters. In a main() method there is only one parameter ,String args[] . args[] is a name of the parameter that is an array of the objects of data type String. String store sequences of characters and args will receive the command line arguments.

All the method in java must be start with opening curly brace ({) and ends with closing curly brace (}).

The next line of the program is

System.out.println("Hello Delhi");

This System.out.println helps to display the output in the command line. The System.out.println statement ends with ; (semicolon). All statements in java must end with semicolon. And remember that java is case sensitive. So we should be very careful about cases while coding the program. Otherwise it will lead to the serious problems.

Previous Home Next

Tolal:0 Click:

Show All Comments

Did not find what you were looking for leave your name and message. We will revert within 24 hours
Name:
eMail:
Comment / Feedback: