is it necessary to create main function in java code example

Example 1: java define main function

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

Example 2: explain main method in java

Main() method is starting point of execution for all java applications.
public static void main(String[] args) {}

String args[] are array of string objects we need to pass from command line 
arguments.
Every Java application must have atleast one main method.
  
public : “public” is an access specifier which can be used outside the class. 
When main method is declared
public it means it can be used outside class.
static : To call a method we require object. Sometimes it may be required 
to call a method without the
help of object. Then we declare that method as static. JVM calls the main() 
method without creating
object by declaring keyword static.
void : void return type is used when a method does’nt return any value . 
main() method does’nt return
any value, so main() is declared as void.