welcome to hello word program

Here let us c the how a basic java program works

class HelloWorld                            // here classname is hello world
{
   public static void main(String args[])
   {
      System.out.println("Hello World");
   }
}

Basic structure of java program is 

class classname                          
{
   public static void main(String args[])
   {
      statement 1;

      statement 2;  

      statement 3; 

      statement 4;  

 } 

 } 

 WHATEVER I SPECIFIED IN RED COLOR ,IT IS MUST FOR ANY A JAVA PROGRAM.

public: public is an access specifier,it can be available anywhere.

public functions are everywhere available.Jvm can be able to call correspondence 

main() function.

static: whenever we mention static keyword ,according to java it can be 

called by classname.Static functions are common functions,they can be called 

without the helpof object.according to java,JVM can be able to call main function

 with the help ofclassname.

void: whenever the main function execution is completed

In c/c++ it has to return a value to the os,since application is directly 

interacting with os .If main function is not returning a value ,

the os is unable to understand the program memory and it is ready to clean up .

That's why to cleanthe memory ,main function has to return a value in c/c++.

Best example is,my mom kept food for me,in the middle i went out what should

my mom think ? similarly os also unable to understand .This problem will be 

identified at large projects in real time,memory is not handling properly,

that is chance of system performance down.

but in java ,we will go for void after complication of program ,JVM will take care .

so no chance of memory wastage. 

main() : main is a name of a function,where program execution is started.

main is the starting point of the program execution and it is ending point 

of program execution.

Every program execution is done inside the stack memory.

when main() is started,stack memory is started,when main is completed stack memory 

also completed.