Collections emptyList/singleton/singletonList/List/Set toArray

Question

Suppose I have this code:

String[] left = { \"1\", \"2\" };
String[] leftNew = Collections.emptyList().toArray(left);
System.out.println(Arrays.toString(left         


        

Answer 1

Code of toArray(T[] a) of (for instance) ArrayList is quite clear:

public  T[] toArray(T[] a) {
    if (a.length < size)
        // Make a new array of a's runtime type, but my contents:
        return (T[]) Arrays.copyOf(elementData, size, a.getClass());
    System.arraycopy(elementData, 0, a, 0, size);
    if (a.length > size)
        a[size] = null;
    return a;
}

If input array's size is bigger than this list's (which means that we can copy all the list's content into this array because it's length is big enough), then the next element reference in the array after all lists content copied (actually the index equal to the size of the list) will be set to point to null.