Executing a class without main in java

You can write a class in java without main() method as here


class DemoFirst{

      static{
      System.out.println("Hello Friends....");
      }
}

and you can execute this class as well , But here is a thing to consider is,  " It is possible with java jdk-1.5 and lower versions ". If you execute this class with jdk-1.6 or higher version you will get an error.
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Compilation and Execution :

D:\Training Data>javac DemoFirst.java

D:\Training Data>java DemoFirst
Error: Main method not found in class DemoFirst, please define the main method as:
   public static void main(String[] args)