I didn't like how this essay misunderstood the design principles in Java's class files. With dynamic binding to the runtime, you can't know for certain the layout of a data structure in memory (e.g. what is the ideal memory alignment?). If the class file is untrusted, you can't even be sure you have a valid data structure in the first place. So allocating the array and then assigning elements one at a time is what you do.