1 package list;
 2 
 3 import java.util.HashMap;
 4 import java.util.Map;
 5 
 6 /**
 7  * 测试map的基本用法
 8  * @author acer
 9  *
10  */
11 public class Hashmap {
12     public static void main(String[] args)
13     {
14         Map map=new HashMap();
15         System.out.println(map.isEmpty());
16         map.put("日本汽车", new car("丰田"));
17         map.put("德国汽车", new car("奥迪"));
18         map.put("日本电器", new camera("canon"));
19         map.put("one", new Integer(1));
20         System.out.println(map.size());
21         car c=(car)map.get("日本汽车");
22         System.out.println(c.name);
23         System.out.println(map.containsKey("日本汽车"));
24         System.out.println(map.containsValue(new car("canon")));
25         System.out.println(map.containsValue(new Integer(1)));
26         map.remove("日本");
27     }
28 }
29 class car{
30     String name;
31     public car(String name)
32     {
33         this.name=name;
34     }
35 }
36 class camera{
37     String name;
38     public camera(String name)
39     {
40         this.name=name;
41     }
42 }

 1 package list;
 2 /**
 3  * 实现较为粗糙的HashMap类
 4  * Map：1，存放键值对2根据键对象找相应的值对象3键值不能重复
 5  * @author acer
 6  *
 7  */
 8 public class myHashMap {
 9     arrmap[] arr=new arrmap[100];//此时暂时不考虑数组扩容问题，只实现一些基本的方法
10     int size;
11     public void put(Object key,Object value)
12     {
13         arrmap newarr=new arrmap(key,value);
14         //解决键值重复的问题
15         for(int i=0;i<size;i++)
16         {
17             if(arr[i].key.equals(key))
18             {
19                 arr[i].value=value;
20                 return;
21             }
22         }
23         arr[size++]=newarr;
24     }
25     public Object get(Object key)
26     {
27         for(int i=0;i<size;i++)
28         {
29             if(arr[i].key.equals(key))
30                 return arr[i].value;
31         }
32         return null;

33     }
34     public boolean containsKey(Object key)
35     {
36         for(int i=0;i<size;i++)
37         {
38             if(arr[i].key.equals(key))
39             {
40                 return true;
41             }
42         }
43         return false;
44     }
45     public boolean containsValue(Object value)
46     {
47         for(int i=0;i<size;i++)
48         {
49             if(arr[i].value.equals(value))
50             {
51                 return true;
52             }
53         }
54         return false;
55     }
56     public static void main(String[] args)
57     {
58         myHashMap arr=new myHashMap();
59         arr.put("日本", new car("丰田"));
60         arr.put("德国", new car("奔驰"));
61         arr.put("美国", new car("福特"));
62         arr.put("日本电器", new camera("canon"));
63         car c=(car)arr.get("日本");
64         System.out.println(c.name);
65         camera d=(camera)arr.get("日本电器");
66         System.out.println(d.name);
67         System.out.println(arr.containsKey("日本"));
68         System.out.println(arr.containsValue(new car("丰田")));
69         arr.put("日本", new car("本田"));
70         c=(car)arr.get("日本");
71         System.out.println(c.name);
72     }
73 }
74  class arrmap
75 {
76     Object key;
77     Object value;
78     public arrmap(Object key,Object value)
79     {
80         this.key=key;
81         this.value=value;
82     }
83 }

 1 package list;
 2 
 3 import java.util.LinkedList;
 4 
 5 /**
 6  * 完善粗糙的myhashmap
 7  * 提高查询效率
 8  * @author acer
 9  *
10  */
11 public class myHashMapUpdate {
12     LinkedList[] arr=new LinkedList[999];
13     int size;
14     public void put(Object key,Object value)
15     {
16         arrmap arra=new arrmap(key,value);
17         int a=key.hashCode()%999;
18         if(arr[a]==null)
19         {
20             LinkedList list=new LinkedList();
21             arr[a]=list;
22             list.add(arra);
23         }
24         else
25         {
26             LinkedList list=arr[a];
27             for(int i=0;i<list.size();i++)
28             {
29                 arrmap arra1=(arrmap)list.get(i);
30                 if(arra1.key.equals(key))
31                 {
32                     arra1.value=value;
33                     return;
34                 }
35             }
36             arr[a].add(arra);
37         }
38     }
39     public Object get(Object key)
40     {
41         int a=key.hashCode()%999;
42         if(arr[a]!=null)
43         {
44             LinkedList list=arr[a];
45             for(int i=0;i<list.size();i++)
46             {
47                 arrmap arra=(arrmap)list.get(i);
48                 if(arra.key.equals(key))
49                 {
50                     return arra.value;
51                 }
52             }
53         }
54         return null;
55     }
56     public static void main(String[] args)
57     {
58         myHashMapUpdate arr=new myHashMapUpdate();
59         arr.put("日本", new car("丰田"));
60         arr.put("日本", new car("本田"));
61         arr.put("德国", new car("奔驰"));
62         arr.put("美国", new car("福特"));
63         arr.put("日本电器", new camera("canon"));
64         car c=(car)arr.get("日本");
65         System.out.println(c.name);
66     }
67 }