1 import java.util.*;
2 class HashMapTest //无序
3 {
4 public static void main(String [] args)
5 {
6 HashMap<Student,String> hs=new HashMap<Student,String>();
7 hs.put(new Student("lisi01",21),"beijing");
8 hs.put(new Student("lisi02",22),"tianjing");
9 hs.put(new Student("lisi02",22),"dongjing");
10 hs.put(new Student("lisi04",24),"shanghai");
11 hs.put(new Student("lisi03",23),"xiamen");
12 //第一种取出方式
13 /*
14 Set<Student> en=hs.keySet(); //这里取出的是student的键，非<Student,String>
15 for(Iterator<Student> it=en.iterator();it.hasNext();)
16 {
17 Student stu=it.next();
18 String address=hs.get(stu);
19 //System.out.println(stu);
20 System.out.println(stu.getName()+".."+stu.getAge()+".."+address); //或者在student类中覆写ｔｏＳｔｒｉｎｇ方法
21 }
22 */
23 //第二种取出方式 entrySet
24 Set<Map.Entry<Student,String>> et=hs.entrySet();
25 for(Iterator<Map.Entry<Student,String>> it=et.iterator();it.hasNext();) //Iterator 泛型别忘了<Map.Entry<Student,String>>
26 {
27 Map.Entry<Student,String> me=it.next();
28 String address=me.getValue();
29 Student info =me.getKey();
30 System.out.println(info.getName()+".."+info.getAge()+".."+address);
31 }
32
33 }
34
35 }
36 class Student implements Comparable<Student> //泛型的使用
37 {
38 private String name;
39 private int age;
40 private String address;
41 Student(String name,int age)
42 {
43 this.name=name;
44 this.age=age;
45 }//用来初始化实例
46 public void setName(String name) //eclipse 用多了，容易写错 （传参）
47 {
48 this.name=name;
49 }
50 public String getName() //类型 以及return语句（无参）
51 {
52 return name;
53 }
54 public void setAge(int age)
55 {
56 this.age=age;
57 }
58 public int getAge()
59 {
60 return age;
61 }
62 /*
63 public String toString()
64 {
65 return this.name+"..."+this.age;
66 }
67 */
68 /*只要是哈希表结构的集合 都需要覆写这两个方法*/
69 public int hashCode() //整型 ,注意Code 首字母大写
70 {
71 return name.hashCode()+age*23;
72 }
73 public boolean equals(Object obj)
74 {
75 if(!(obj instanceof Student))
76 {
77 throw new ClassCastException("类型不匹配");
78 }
79 Student s=(Student)obj;
80 return this.name.equals(s.name)&&this.age==s.age; //别什么都写成this.age.equals(s.age)
81 }
82 //如果存储对象使用到二叉树结构集合，则需要进行内部排序。
83 public int compareTo(Student s)
84 {
85 int num =new Integer(this.age).compareTo(new Integer(s.age));
86 if(num==0)
87 {
88 return this.name.compareTo(s.name);
89 }
90 return num;
91 }
92 }