Question

How can I create/instantiate an array to be equal to the substring of another array, where the size of the substring is unknown:

int n; //some number derived somewhere else

String[] grp = elements[i] to elements[i+n];

Answer 1

Use Arrays.copyOfRange:

public static <T> T[] copyOfRange(T[] original,
                                  int from,
                                  int to)

Copies the specified range of the
specified array into a new array. The
initial index of the range (from) must
lie between zero and original.length,
inclusive. The value at original[from]
is placed into the initial element of
the copy (unless from ==
original.length or from == to). Values
from subsequent elements in the
original array are placed into
subsequent elements in the copy. The
final index of the range (to), which
must be greater than or equal to from,
may be greater than original.length,
in which case null is placed in all
elements of the copy whose index is
greater than or equal to
original.length - from. The length of
the returned array will be to - from.

The resulting array is of exactly the
same class as the original array.

In your case:

String[] grp = Arrays.copyOfRange(elements, i, i + n);