Java List toArray(T[] a) implementation

Question

I was just looking at the method defined in the List interface:

Returns an array containing all of the elements in this list in the correct order; the

Answer 1

This method is a holdover from pre-1.5 Java. Here is the link to javadoc

Back then it was the only way to convert a list to a reifiable array.

It is an obscure fact, but although you can store anything in the Object[] array, you cannot cast this array to more specific type, e.g.

Object[] generic_array = { "string" };

String[] strings_array = generic_array; // ClassCastException

Seemingly more efficient List.toArray() does just that, it creates a generic Object array.

Before Java generics, the only way to do a type-safe transfer was to have this cludge:

String[] stronglyTypedArrayFromList ( List strings )
{
    return (String[]) strings.toArray( new String[] );
    // or another variant
    // return (String[]) strings.toArray( new String[ strings.size( ) ] );
}

Thankfully generics made these kind of machinations obsolete. This method was left there to provide backward compatibility with pre 1.5 code.