1 //: SpringDetector2.java 2 package cn.skyfffire; 3  4 import java.util.Enumeration; 5 import java.util.Hashtable; 6  7 /** 8 * @user: skyfffire 9 * @data: 2017年3月14日 10 * @time: 下午6:31:1311 */12 class Groundhog2 {13     int ghNumber;14     15     Groundhog2(int n) {16         ghNumber = n;17     }18     19     // Hashtable的get方法要使用这个方法20     @Override21     public int hashCode() {22         return ghNumber;23     }24     25     // HashTable的containsKey要使用26     @Override27     public boolean equals(Object o) {28         return (o instanceof Groundhog2) 29                 && (ghNumber == ((Groundhog2)o).ghNumber);30     }31 }32 33 public class SpringDetector2 {34     public static void main(String[] args) {35         // 为了方便查看其中的键值对，复写了Hashtable的toString36         Hashtable
     
       ht = 37                 new Hashtable
      
       () {38                     private static final long serialVersionUID = -8222553412985239408L;39 40                     @Override41                     public String toString() {42                         String str = "";43                         Enumeration
       
         ge = this.keys();44                         45                         while (ge.hasMoreElements()) {46                             Groundhog2 gh2 = ge.nextElement();47                             48                             str += (gh2 + " = " + this.get(gh2) + "\n");49                         }50                         51                         return str;52                     }53         };54         55         // 添加十个键值对56         for (int i = 0; i < 10; i++) {57             ht.put(new Groundhog2(i), new Prediction());58         }59         60         // 查看键值对中的内容61         System.out.println(ht.toString());62         System.out.println(63                 "Looking up prediction for groundhog #3:");64         65         // 复写了hashCode之后可以方便地比较ghNumber相同的键66         Groundhog2 hg = new Groundhog2(3);67         68         if (ht.containsKey(hg)) {69             System.out.println((Prediction)ht.get(hg));70         }71     }72 }73 74 ///:~