What's the reason I can't create generic array types in Java? - Stack Overflow

It's because Java's arrays (unlike generics) contain, at runtime, information about its component type. So you must know the component type when you create the array. Since you don't know what T is at runtime, you can't create the array.

Arrays of generic types are not allowed because they're not sound. The problem is due to the interaction of Java arrays, which are not statically sound but are dynamically checked, with generics, which are statically sound and not dynamically checked. Here is how you could exploit the loophole:

Box<String>[] bsa = null // new Box<String>[3]; This is why we can't allow generic array
        Object[] oa = bsa;
        oa[0] = new Box<Integer>(3); // error not caught by array store check
        String s = bsa[0].x; // BOOM!

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