package com.lanxi.demo1_3;

 public class Student {

     private String name;

     private String sex;

     private int age;

     @Override//重写toString方法

     public String toString() {

         return "Student [name=" + name + ", sex=" + sex + ", age=" + age + "]";

     }

     public Student() {//无参构造方法

         super();

     }

     public Student(String name, String sex, int age) {//有参构造方法

         super();

         this.name = name;

         this.sex = sex;

         this.age = age;

     }

     //getter，setter方法

     public String getName() {

         return name;

     }

     public String getSex() {

         return sex;

     }

     public int getAge() {

         return age;

     }

 }

 package com.lanxi.demo1_3;

 import java.util.HashMap;

 import java.util.Iterator;

 import java.util.Map;

 import java.util.Map.Entry;

 import java.util.Scanner;

 public class Test {

     public static void main(String[] args) {

         System.out.println("请输入学生编号");

         Scanner input=new Scanner(System.in);

         Integer num=input.nextInt();

         Map map=new HashMap();

         map.put(1, new Student("张三","男",18));

         map.put(2, new Student("李四","男",20));

         map.put(3, new Student("小花","女",16));

         map.put(4, new Student("大花","女",18));

         //遍历

         Iterator it=map.entrySet().iterator();

         while(it.hasNext()){

             Entry en=(Entry)it.next();

             //查看输入的学生编号，集合中是否存在

             if ((map.containsKey(num))||(num==(Integer)en.getKey())) {

                 //如果存在，输出“存在”，并输出该学生信息

                 System.out.println("存在");

                     System.out.println(map.get(num));

                     break;

             }else{

                 //如果不存在，则输出“不存在”

                 System.out.println("不存在");

                 break;

             }

         }

         System.out.println();

         System.out.println("移除后遍历");

         map.remove(4);

         Iterator it1=map.entrySet().iterator();

         while(it1.hasNext()){

             System.out.println(it1.next());

         }

     }

 }