Basics for Beginners in java.

If you are the new for java then you must learn the concept given below. First go through the following example and than you will be able to understand the basic logic the JAVA program .

First program in java..

Class A

{

public static void main(String arg[])

{

System.out.println("java is a very interesting language");

}

}

Logic behind the public method in JAVA

The public keyword is an access specifier, which allows the programmer to control

the visibility of class members. When a class member is preceded by public, then that member may be accessed by code outside the class in which it is declared. (The opposite

of public is private, which prevents a member from being used by code defined outside of its class.) In this case, main( ) must be declared as public, since it must be called by code outside of its class when the program is started.

Logic behind the static keyword in the above code.

The keyword static allows main( ) to be called without having to instantiate a particular instance of the class. This is necessary since main( ) is called by the Java interpreter before any objects are made.

Logic behind the void keyword in the above code.

The keyword void simply tells the compiler that main( ) does not return a value.

Logic behind the void keyword in the above code.

In JAVA , main( ) is the method called when a Java application begins. Be careful that Java is case-sensitive. Thus, Main is different from main. It is important to understand that the Java compiler will compile classes that do not contain a main( ) method. But the Java interpreter has no way to run these classes. So, if you had typed Main instead of main, the compiler would still compile your program. However, the Java interpreter would report an error because it would be unable to find the main( ) method.

Logic behind the String arg[] in the above code.

In main( ), there is only one parameter. String args[ ] declares a parameter named args, which is an array of instances of the class String. (Arrays are collections of similar objects.) Objects of type String store character strings. In this case, args receives any command-line arguments present when the program is executed.

Logic behind the System.out in the above code.

System is a class.

Out is a static object.

Println() is the method of PrintStream class.

System.out refers to the standard output stream.