package com.imooc.collection;import java.util.HashSet;
import java.util.Set;
/*** 学生类* @author Monica**/public class Student {public String id;public String name;public Set<Course> courses;public Student(String id,String name){this.id = id;this.name = name;this.courses = new HashSet<Course>();//set接口调用}@Overridepublic int hashCode() {final int prime = 31;int result = 1;result = prime * result + ((name == null) ? 0 : name.hashCode());return result;}@Overridepublic boolean equals(Object obj) {if (this == obj)return true;if (obj == null)return false;if (!(obj instanceof Student))return false;Student other = (Student) obj;if (name == null) {if (other.name != null)return false;} else if (!name.equals(other.name))return false;return true;}}

package com.imooc.collection;import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Scanner;
import java.util.Set;public class MapTest {/*** 用来承装学生类型对象* @param args*/public Map<String,Student> students;/*** 在构造方法中初试化students属性* @param args*/public MapTest(){this.students = new HashMap<String,Student>();}/*** 测试添加：输入学生ID，判断是否被占用* 若未被占用，则输入姓名，创建新学生对象，并且添加到students中* @param args*/public void testPut(){//创建一个Scanner对象，用来获取输入的学生ID和姓名Scanner console = new Scanner(System.in);int i = 0;while (i<3){System.out.println("请输入学生ID：");String ID = console.next();//判断该ID是否被占用Student st = students.get(ID);if(st==null){System.out.println("请输入学生姓名：");String name = console.next();//创建新的学生对象Student newStudent = new Student(ID,name);//通过调用students的put方法，添加ID-学生映射students.put(ID, newStudent);System.out.println("成功添加学生："+students.get(ID).name);i++;}else{System.out.println("该学生ID已被占用！");continue;}}}/*** 测试Map中是否包含某个Key值或value值*/public void testContainsKeyOrValue(){//提示输入学生idSystem.out.println("请输入要查询的学生ID：");Scanner console = new Scanner(System.in);String id = console.next();//在Map中，用containsKey()方法，来判断是否包含某个Key值System.out.println("您输入的学生ID为："+id+",在学生映射表中是否存在："+students.containsKey(id));if(students.containsKey(id))System.out.println("对应的学生为："+students.get(id).name);//提示输入学生姓名System.out.println("请输入要查询的学生姓名：");String name = console.next();//在containsValue()方法，来判断是否包含某个Value值if(students.containsValue(new Student(null,name)))System.out.println("在学生映射表中，确实包含学生："+name);elseSystem.out.println("在学生映射表中不存在该学生！");}/*** 测试Map的keySet方法* @param args*/public void testKeySet(){//通过keySet方法，返回Map中的所有“键”的Set集合Set<String> keySet = students.keySet();//取得Map的容量，调用set方法System.out.println("总共有"+keySet.size()+"个学生");//通过遍历KeySet对象，取得每一个键，在调用get方法取得每个键对应的valuefor(String stuId:keySet){Student st = students.get(stuId);if(st!=null)System.out.println("学生："+st.name);}}/*** 测试删除Map中的映射* @param args*/public void testRemove(){//获取从键盘输入的待删除学生Id字符串Scanner console = new Scanner(System.in);while(true){//提示输入待删除的学生的ID System.out.println("请输入要删除的学生ID！");String ID = console.next();//判断该ID是否有对应的学生对象Student st = students.get(ID);if(st==null){//提示输入的ID并不存在System.out.println("该ID不存在！");continue;}else{students.remove(ID);System.out.println("成功删除学生："+st.name);break;}}}/*** 通过entrySet方法来遍历Map* @param args*/public void testEntrySet(){//通过entrySet方法，返回Map中的所有键值对Set<Entry<String,Student>> entrySet = students.entrySet();for(Entry<String,Student> entry:entrySet){System.out.println("取得键："+entry.getKey());System.out.println("对应的值为："+entry.getValue().name);}}/*** 利用put方法修改Map中已有映射* @param args*/public void testModify(){//提示输入要修改的学生IdSystem.out.println("请输入要修改的学生ID：");//创建一个Scanner对象，去获取从键盘输入的学生ID字符串Scanner console = new Scanner(System.in);while(true){//取得从键盘输入的学生IDString stuID = console.next();//从students中查找该学生ID对应的学生对象Student student = students.get(stuID);if(student == null){System.out.println("该ID不存在！请重新输入！");continue;}//提示当前对应的学生对象的姓名System.out.println("当前该学生ID，所对应的学生为："+student.name);//提示输入新的学生姓名，来修改已有的映射System.out.println("请输入新的学生姓名：");String name = console.next();Student newStudent = new Student(stuID,name);students.put(stuID, newStudent);System.out.println("修改成功！");break;}}public static void main(String[] args) {// TODO Auto-generated method stubMapTest mt = new MapTest();mt.testPut();mt.testKeySet();//mt.testRemove();//mt.testEntrySet();//mt.testModify();//mt.testEntrySet();mt.testContainsKeyOrValue();}}