11.7

实验18：迭代器模式

本次实验属于模仿型实验，通过本次实验学生将掌握以下内容： 

1、理解迭代器模式的动机，掌握该模式的结构；

2、能够利用迭代器模式解决实际问题。

 

[实验任务一]：JAVA和C++常见数据结构迭代器的使用

信1305班共44名同学，每名同学都有姓名，学号和年龄等属性，分别使用JAVA内置迭代器和C++中标准模板库（STL）实现对同学信息的遍历，要求按照学号从小到大和从大到小两种次序输出学生信息。

实验要求：

1. 搜集并掌握JAVA和C++中常见的数据结构和迭代器的使用方法，例如，vector, list, map和set等；

2. 提交源代码；

3. 注意编程规范。

import java.util.*;

 

class Student

{

    int id;

    String name;

    int age;

 

    public Student(int id, String name, int age)

    {

        this.id = id;

        this.name = name;

        this.age = age;

    }

}

 

public class List_Iterator

{

    public static void sortById(List list)

    {

        Iterator<Student> sIterator = list.iterator();

        while (sIterator.hasNext())

        {

            Student student = sIterator.next();

            System.out.println("学号: " + student.id + ", 姓名: " + student.name + ", 年龄: " + student.age);

        }

    }

 

    public static void main(String[] args)

    {

        List<Student> studentList = new ArrayList<>();

        studentList.add(new Student(20213971, "门殿宇", 20));

        studentList.add(new Student(20211234, "张三", 20));

        studentList.add(new Student(20214352, "李四", 20));

        studentList.add(new Student(20210123, "王五", 20));

        studentList.add(new Student(20214444, "小明", 20));

        studentList.add(new Student(20215423, "小李", 20));

        studentList.add(new Student(20217462, "小王", 20));

        studentList.add(new Student(20212344, "小张", 20));

        studentList.add(new Student(20213888, "小刘", 20));

        studentList.add(new Student(20219999, "小马", 20));

 

 

        //按学号升序排序

        Collections.sort(studentList, Comparator.comparingInt(student -> student.id));

 

        //用迭代器打印

        System.out.println("按学号升序:");

        sortById(studentList);

 

 

        Collections.reverse(studentList);

        //迭代器打印降序学号

        System.out.println("\n按学号降序:");

        sortById(studentList);

    }

}

 

 

#include <iostream>

#include <vector>

#include <algorithm>

 

using namespace std;

 

// 自定义数据类型

class Student

{

public:

    int id;

    string name;

    int age;

 

public:

    Student(int id, string name, int age) : id(id), name(name), age(age)

    {}

};

 

// 比较函数，按学号升序排序

bool compareByIdUp(const Student &a, const Student &b)

{

    return a.id < b.id;

}

 

//按学号降序排序

bool compareByIdDown(const Student &a, const Student &b)

{

    return a.id > b.id;

}

 

// 打印学生信息

void printStudentInfo(vector<Student> &v)

{

    for (vector<Student>::iterator it = v.begin(); it != v.end(); it++)

    {

        cout << "学号:" << (*it).id << "  姓名:" << (*it).name << "  年龄:" << (*it).age << endl;

    }

    cout << endl;

}

 

int main()

{

    vector<Student> students;

    students.emplace_back(20213971, "门殿宇", 20);

    students.emplace_back(20211234, "张三", 20);

    students.emplace_back(20214352, "李四", 20);

    students.emplace_back(20210123, "王五", 20);

    students.emplace_back(20214444, "小明", 20);

    students.emplace_back(20215423, "小李", 20);

    students.emplace_back(20217462, "小王", 20);

    students.emplace_back(20212344, "小张", 20);

    students.emplace_back(20213888, "小刘", 20);

    students.emplace_back(20219999, "小马", 20);

 

    // 使用 sort 函数和比较函数按学号升序排序

    sort(students.begin(), students.end(), compareByIdUp);

 

    cout << "按学号升序排列" << endl;

    // 打印排序后的学生信息

    printStudentInfo(students);

 

 

    // 使用 sort 函数和比较函数按学号降序排序

    sort(students.begin(), students.end(), compareByIdDown);

 

    cout << "按学号降序排列" << endl;

    // 打印排序后的学生信息

    printStudentInfo(students);

 

    return 0;

}