Siraj Choudhary code will work.

class Sample
{

    static String str="Hello";

    static {

        System.out.println(str);

    }

    public static void main(String [] args)
    {
           System.out.println("in main method");
    }
}

Print the statement inside a static block of code. Static blocks get executed when the class gets loaded into the memory and even before the creation of an object. Hence it will be executed before the main() method. And it will be executed only once.