1 package cn.demo;
 2
 3 import java.util.ArrayList;
 4 import java.util.List;
 5
 6 public class TestHash {
 7     public static void main(String[] args) throws Exception {
 8         List<String> set = new ArrayList<String>();
 9         set.add("java");
10         set.add("html");
11         set.add("jsp");
12         set.add("ajax");
13         System.out.println(set);
14         System.out.println(set.get(2));
15         System.out.println(set.contains("java"));
16         Object obj [] = set.toArray() ; // 不可能使用
17         for (int x = 0 ; x < obj.length ; x ++) {
18             System.out.println(obj[x]);
19         }
20     }
21 }

 1 package cn.demo;
 2
 3 import java.util.ArrayList;
 4 import java.util.List;
 5
 6 class Phone{
 7     private String name;
 8     private double price;
 9     public Phone(String name,double price){
10         this.name =name;
11         this.price = price;
12     }
13
14     @Override
15     public String toString() {
16         return "Phone [name=" + name + ", price=" + price + "/n";
17     }
18
19     @Override
20     public boolean equals(Object obj) {
21         if (this == obj)
22             return true;
23         if (obj == null)
24             return false;
25         if (getClass() != obj.getClass())
26             return false;
27         Phone other = (Phone) obj;
28         if (name == null) {
29             if (other.name != null)
30                 return false;
31         } else if (!name.equals(other.name))
32             return false;
33         if (Double.doubleToLongBits(price) != Double.doubleToLongBits(other.price))
34             return false;
35         return true;
36     }
37 }
38 public class TestDemo {
39     public static void main(String[] args) {
40         List<Phone> all = new ArrayList<Phone>();
41         all.add(new Phone("xiao米",20.9));
42         all.add(new Phone("大米",20));
43         System.out.println(all.contains(new Phone("大米",20)));
44         all.remove(new Phone("xiao米",20.9));
45         System.out.println(all);
46     }
47 }