软件设计实验18：迭代器模式

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；

Java:

数据结构：

 

1.ArrayList:

 

   ArrayList<Integer> arrayList = new ArrayList<>();

   arrayList.add(1);

   arrayList.add(2);

   arrayList.add(3);

 

 

2.LinkedList:

 

   LinkedList<String> linkedList = new LinkedList<>();

   linkedList.add("A");

   linkedList.add("B");

   linkedList.add("C");

 

 

3.HashMap:

 

   HashMap<String, Integer> hashMap = new HashMap<>();

   hashMap.put("one", 1);

   hashMap.put("two", 2);

   hashMap.put("three", 3);

 

 

4.HashSet:

 

   HashSet<String> hashSet = new HashSet<>();

   hashSet.add("apple");

   hashSet.add("orange");

   hashSet.add("banana");

 

迭代器：

 

5.Iterator (for ArrayList, LinkedList):

 

   Iterator<Integer> iterator = arrayList.iterator();

   while (iterator.hasNext()) {

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

   }

 

 

6.HashMap EntrySet Iterator:

 

   for (Map.Entry<String, Integer> entry : hashMap.entrySet()) {

       System.out.println(entry.getKey() + ": " + entry.getValue());

   }

 

 

7.HashSet Iterator:

 

   Iterator<String> iterator = hashSet.iterator();

   while (iterator.hasNext()) {

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

   }

 

C++:

数据结构：

 

8.Vector:

 

   #include <vector>

   std::vector<int> vectorInt = {1, 2, 3};

 

 

9.List:

 

   #include <list>

   std::list<std::string> listString = {"A", "B", "C"};

 

 

10.Map:

 

   #include <map>

   std::map<std::string, int> mapInt = {{"one", 1}, {"two", 2}, {"three", 3}};

 

 

11.Set:

 

   #include <set>

   std::set<std::string> setString = {"apple", "orange", "banana"};

 

迭代器：

 

12.Iterator (for Vector, List):

 

   for (auto it = vectorInt.begin(); it != vectorInt.end(); ++it) {

       std::cout << *it << std::endl;

   }

 

 

13.Map Iterator:

 

   for (auto it = mapInt.begin(); it != mapInt.end(); ++it) {

       std::cout << it->first << ": " << it->second << std::endl;

   }

 

 

14.Set Iterator:

 

   for (auto it = setString.begin(); it != setString.end(); ++it) {

       std::cout << *it << std::endl;

   }

 

需要注意的是，C++11及以后版本引入了更方便的范围-based for 循环，可以简化上述的迭代器使用。例如：

// 使用范围-based for 循环遍历 Vector

for (const auto& element : vectorInt) {

    std::cout << element << std::endl;

}

 

// 使用范围-based for 循环遍历 Map

for (const auto& entry : mapInt) {

    std::cout << entry.first << ": " << entry.second << std::endl;

}

 

// 使用范围-based for 循环遍历 Set

for (const auto& element : setString) {

    std::cout << element << std::endl;

}

2. 提交源代码；

 

public class Student2 implements Comparable<Student2>{
    private int studentid;
    private String name;
    private int age;

    public Student2(int studentid, String name, int age) {
        super();
        this.studentid = studentid;
        this.name = name;
        this.age = age;
    }

    // 三个返回结果都要写出来
    public int compareTo(Student2 o) {
        if(this.studentid < o.studentid){
            return -1;
        }else if(this.studentid > o.studentid){
            return 1;
        }else {
            return 0;
        }
    }

    @Override
    public String toString(){
        return "姓名: " + this.name + ". 学号: " + this.studentid + ". 年龄: " + this.age;
    }
}

 

public class Student implements Comparable<Student>{
    private int studentid;
    private String name;
    private int age;

    public Student(int studentid, String name, int age) {
        super();
        this.studentid = studentid;
        this.name = name;
        this.age = age;
    }

    // 三个返回结果都要写出来
    public int compareTo(Student o) {
        if(this.studentid > o.studentid){
            return -1;
        }else if(this.studentid < o.studentid){
            return 1;
        }else {
            return 0;
        }
    }

    @Override
    public String toString(){
        return "姓名: " + this.name + ". 学号: " + this.studentid + ". 年龄: " + this.age;
    }
}

 

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

public class Client {
    public static void main(String[] args) {
        Student s1 = new Student(20213825, "杰克逊", 20);
        Student s2 = new Student(20213999, "孙文亮", 20);
        Student s3 = new Student(20216654, "阿giao", 20);
        Student s4 = new Student(20213367, "丽丽", 20);
        Student s5 = new Student(20213396, "全险半挂", 20);
        Student s6 = new Student(20213396, "农村国宝", 20);
        Student2 s7 = new Student2(20213825, "杰克逊", 20);
        Student2 s8 = new Student2(20213999, "孙文亮", 20);
        Student2 s9 = new Student2(20216654, "阿giao", 20);
        Student2 s10 = new Student2(20213367, "丽丽", 20);
        Student2 s11 = new Student2(20213396, "全险半挂", 20);
        Student2 s12 = new Student2(20213396, "农村国宝", 20);
        List<Student> list = new ArrayList<Student>();
        list.add(s1);
        list.add(s2);
        list.add(s3);
        list.add(s4);
        list.add(s5);
        list.add(s6);
        Collections.sort(list);
        System.out.println("按照学号从大到小输出: ");
        for(Student stu : list){
            System.out.println(stu.toString());
        }
        System.out.println("---------------------------------------");
        List<Student2> list2 = new ArrayList<Student2>();
        list2.add(s7);
        list2.add(s8);
        list2.add(s9);
        list2.add(s10);
        list2.add(s11);
        list2.add(s12);
        Collections.sort(list2);
        System.out.println("按照学号从小到大输出: ");
        for(Student2 stu : list2){
            System.out.println(stu.toString());
        }
    }
}

 

 

3. 注意编程规范。