java - Trying to shuffle a "Deck" class, doesn't seem to be shuffling -

i've written deck class , have shuffle it, , print out few hands check how works. however, doesn't seem shuffle anything, rather give exact same deck.

public void makehands () {     deck deck = new deck ();     deck shuffled = shuffledeck (deck);     printdeck (subdeck (shuffled, 0, 4));     printdeck (subdeck (shuffled, 5, 9));     printdeck (subdeck (shuffled, 10, 14));     printdeck (subdeck (shuffled, 15, 19)); }  public static int randomint (int length, int i) {     double x = math.random () * length;     int g = (int) x;     return g; }  public deck shuffledeck (deck deck) {     (int i=0; i<deck.cards.length; i++) {         int g = randomint (deck.cards.length, i);         swapcards (i, g);     }     return deck; } }   public void swapcards (int first, int swap) {          card temp = cards[first];          cards[first] = cards[swap];          cards[swap] = temp; } 

the code looks incomplete.

it looks need pass deck object swapcards method.

swapcards() referring cards array. n't clear array declared. instead should pass deck method , swap deck.cards[first] , deck.cards[swap].