Function reverse() directly works on 5 primitive data-types ( boolean, byte, char, int, float) + String objects.

byte[] b = {1, 2, 3, 4, 5};
println(b);
println();

b = reverse(b);
println(b);

exit();

For the less fortunate primitive data-types ( short, long and double) + for any object which isn't a String,
we gotta explicit use a (cast[]) operator on a returning Array from reverse().

That is so b/c they're internally treated as a generalized Object data-type.
And needs to be converted back to their specific data-type.

Outta curiosity, check out how the short primitive data-type is so prejudiced and ignored by Processing,
that even println() doesn't work on it! 

short[] s = {1, 2, 3, 4, 5};
println(s);
println();

s = (short[]) reverse(s);
println(s);

exit();

And finally an example using PVector objects, which you can use as a template for your RPoint ones:

final int NUM = 5;
PVector[] vecs = new PVector[NUM];

for (int i = 0; i != NUM; ++i)
  vecs[i] = new PVector(i, i+i, i*i);

println(vecs);
println();

vecs = (PVector[]) reverse(vecs);

println(vecs);

exit();