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 TreeSetTest
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
19:       {
20:          public int compare(Object firstObject, Object secondObject)
21:          {
22:             Coin first = (Coin)firstObject;
23:             Coin second = (Coin)secondObject;
24:             if (first.getValue() < second.getValue()) return -1;
25:             if (first.getValue() == second.getValue()) return 0;
26:             return 1;
27:          }
28:       }
29: 
30:       Comparator comp = new CoinComparator();
31:       Set coins = new TreeSet(comp);
32:       coins.add(coin1);
33:       coins.add(coin2);
34:       coins.add(coin3);
35:       coins.add(coin4);
36: 
37:       Iterator iter = coins.iterator();
38:       while (iter.hasNext())
39:          System.out.println(iter.next());
40:    }
41: }