1 /**
 2  * Created by Luts on 2015/12/5.
 3  */
 4 public class Course {
 5     private String id;
 6     private String name;
 7     public Course(String id, String name){
 8         this.id = id;
 9         this.name = name;
10     }
11 
12     public Course(){}
13 
14     public String getId() {
15         return id;
16     }
17 
18     public void setId(String id) {
19         this.id = id;
20     }
21 
22     public String getName() {
23         return name;
24     }
25 
26     public void setName(String name) {
27         this.name = name;
28     }
29 }

 1 import java.util.*;
 2 
 3 /**
 4  * Created by Luts on 2015/12/5.
 5  */
 6 public class Student {
 7     private String id;
 8     private String name;
 9     private Set<Course> courses;
10 
11     public Student(String id, String name){
12         this.id = id;
13         this.name = name;
14         this.courses = new HashSet<Course>();
15     }
16 
17     public String getId() {
18         return id;
19     }
20 
21     public void setId(String id) {
22         this.id = id;
23     }
24 
25     public String getName() {
26         return name;
27     }
28 
29     public void setName(String name) {
30         this.name = name;
31     }
32 
33     public Set<Course> getCourses() {
34         return courses;
35     }
36 
37     public void setCourses(Set<Course> courses) {
38         this.courses = courses;
39     }
40 
41 }

  1 import javax.swing.text.html.parser.Entity;
  2 import java.util.HashMap;
  3 import java.util.Map;
  4 import java.util.Scanner;
  5 import java.util.Set;
  6 import java.util.Map.*;
  7 
  8 /**
  9  * Created by Luts on 2015/12/5.
 10  */
 11 public class MapTest {
 12 
 13     //创建Map的学生类型
 14     public Map<String, Student> students;
 15 
 16     //初始化学生类型
 17     public MapTest(){
 18         this.students = new HashMap<String, Student>();
 19     }
 20 
 21 
 22     public void testPut(){
 23         Scanner input =  new Scanner(System.in);
 24         int i = 0;
 25         while (i < 3){
 26             System.out.println("输入学生ID");
 27             String ID = input.next();
 28             Student st = students.get(ID);
 29             if (st == null){
 30                 System.out.println("输入学生姓名");
 31                 String name = input.next();
 32                 Student newStudent = new Student(ID, name);
 33                 students.put(ID, newStudent);
 34                 System.out.println("新添加学生：" + students.get(ID).getName());
 35                 i++;
 36             }else {
 37                 System.out.println("该学生ID已被占用");
 38                 continue;
 39             }
 40         }
 41     }
 42 
 43     public void testKeySet(){
 44         Set<String> keySet = students.keySet(); //通过keySet方法返回Map值所有“键”的set集合
 45 
 46         //取得students容量
 47         System.out.println("总共有："+students.size() +"个学生");
 48 
 49         //遍历keySet，取得键对应的值
 50         for (String stuID : keySet){
 51             Student st = students.get(stuID);
 52             if (st != null){
 53                 System.out.println("学生：" + st.getName());
 54             }
 55         }
 56 
 57     }
 58 
 59 
 60     public void testRemove(){
 61         Scanner input = new Scanner(System.in);
 62         while (true){
 63             System.out.println("输入要删除的学生ID");
 64             String ID = input.next();
 65             Student st = students.get(ID);
 66             if (st == null){
 67                 System.out.println("该学生ID不存在");
 68                 continue;
 69             }
 70             System.out.println("成功删除学生：" + students.get(ID).getName());
 71             break;
 72         }
 73     }
 74 
 75     //通过entrySet方法遍历Maop
 76     public void testEntrySet(){
 77         Set<Entry<String, Student>>entrySet = students.entrySet();
 78         for (Entry<String, Student>entry : entrySet){
 79             System.out.println("取得键：" + entry.getKey());
 80             System.out.println("对应的值为：" + entry.getValue().getName());
 81         }
 82     }
 83 
 84     public void testModify() {
 85         // 提示输入要修改的学生ID
 86         System.out.println("请输入要修改的学生ID：");
 87         // 创建一个Scanner对象，去获取从键盘上输入的学生ID字符串
 88         Scanner input = new Scanner(System.in);
 89         while (true) {
 90             // 取得从键盘输入的学生ID
 91             String stuID = input.next();
 92             // 从students中查找该学生ID对应的学生对象
 93             Student student = students.get(stuID);
 94             if (student == null) {
 95                 System.out.println("该ID不存在！请重新输入！");
 96                 continue;
 97             }
 98             // 提示当前对应的学生对象的姓名
 99             System.out.println("当前该学生ID，所对应的学生为：" + student.getName());
100             // 提示输入新的学生姓名，来修改已有的映射
101             System.out.println("请输入新的学生姓名：");
102             String name = input.next();
103             Student newStudent = new Student(stuID, name);
104             students.put(stuID, newStudent);
105             System.out.println("修改成功！");
106             break;
107         }
108     }
109 
110 
111 
112     public static void main(String[] args){
113         MapTest mt = new MapTest();
114         mt.testPut();
115         mt.testKeySet();
116         mt.testRemove();
117         //mt.testEntrySet();
118         // mt.testModify();
119         // mt.testEntrySet();
120 
121     }
122 }