01: import java.util.Comparator;
02: import java.util.Iterator;
03: import java.util.Set;
04: import java.util.TreeSet;
05: 
06: /**
07:    A program to test hash codes of coins.
08: */
09: public class TreeSetTester
10: {
11:    public static void main(String[] args)
12:    {
13:       Coin coin1 = new Coin(0.25, "quarter");
14:       Coin coin2 = new Coin(0.25, "quarter");
15:       Coin coin3 = new Coin(0.01, "penny");
16:       Coin coin4 = new Coin(0.05, "nickel");
17: 
18:       class CoinComparator implements Comparator<Coin>
19:       {
20:          public int compare(Coin first, Coin second)
21:          {
22:             if (first.getValue() < second.getValue()) return -1;
23:             if (first.getValue() == second.getValue()) return 0;
24:             return 1;
25:          }
26:       }
27: 
28:       Comparator<Coin> comp = new CoinComparator();
29:       Set<Coin> coins = new TreeSet<Coin>(comp);
30:       coins.add(coin1);
31:       coins.add(coin2);
32:       coins.add(coin3);
33:       coins.add(coin4);
34: 
35:       for (Coin c : coins)
36:          System.out.println(c);
37:    }
38: }