> -it uses 52 cards,

Each card  would be a Object that hold information about the kind of card
it is.

Card[] cards  = new Card[52];

Place Card objects into the array.

> -randomized piling of cards

There is a randomize in the collections framework. If you are not using
a collection you could always make the cards comparable.

> -4 cards per pile

A pile could be a List of some kind.

> -line up 8 piles with the topmost card shown.

Textualy or Graphicly?

> -If any of that card has the same with any card in different
> pile, they get paired and the two cards disappear

Same face? Same value? Same face and value?

Anyway comparable might be the answer, or if not that I would imagine
that the cards would all have a int value for both the face and the card
value.

> -then, the next cards will be shown  where the previous  cards are
> located

Textualy or graphicly?

Textualy it is realy simple, graphicly you are probably asking for quite
a bit of work all on its own.

The making of card games seems to be used quite often in teaching
collections.