From http://gihyo.jp/dev/serial/01/java-calculation/0076?page=2

HashSearch.java

01:import java.util.Hashtable;
02:
03:public class HashSearch {
04:
05:  public static int exec(Hashtable vals, int target) {
06:    if (vals.containsKey(target)) {
07:      return (Integer) vals.get(target);
08:    } else {
09:      return -1;
10:    }
11:  }// end of exec
12:
13:  public static void main(String[] args) {
14:    int len = 100000;
15:    int[] data;
16:    data = new int[len];
17:    for(int i=0; i<len; ++i) data[i]=i;
18:    Hashtable <Integer, Integer>hasharray = new Hashtable<Integer, Integer>();
19:    for (int i=0; i<data.length; ++i){
20:      hasharray.put(data[i],i);
21:    }
22:    int result;
23:    int repeat = 10000;
24:    long time;
25:    time = System.currentTimeMillis();
26:    for (int i=0; i<repeat; ++i){
27:      HashSearch.exec(hasharray,3);
28:      HashSearch.exec(hasharray,27);
29:      HashSearch.exec(hasharray,(int)(len/2));
30:      HashSearch.exec(hasharray,(int)(len*2));
31:   }
32:   time = System.currentTimeMillis() - time;
33:   System.out.println(time + "[msec]passed.");
34:  }// end of main
35:
36:
37:  private static void resultPrint(int result){
38:   if (result != -1) {
39:     System.out.println("[ Found ] index key = " + result);
40:   } else {
41:     System.out.println("[Not Found]");
42:   }
43:  }// end of resultPrint
44:
45:}// end of HashSearch