实验18:迭代器模式

发布时间 2024-01-09 15:10:38作者: wardream

 


[实验任务一]JAVAC++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;

List是有序的Collection,使用此接口能够精确的控制每个元素插入的位置。用户能够使用索引(元素在List中的位置,类似于数组下标)来访问List中的元素,这类似于Java的数组。和下面要提到的Set不同,List允许有相同的元素。

除了具有Collection接口必备的iterator()方法外,List还提供一个listIterator()方法,返回一个ListIterator接口,和标准的Iterator接口相比,ListIterator多了一些add()之类的方法,允许添加,删除,设定元素,还能向前或向后遍历。

Vector非常类似ArrayList,但是Vector是同步的。由Vector创建的Iterator,虽然和ArrayList创建的Iterator是同一接口,但是,因为Vector是同步的,当一个Iterator被创建而且正在被使用,另一个线程改变了Vector的状态(例如,添加或删除了一些元素),这时调用Iterator的方法时将抛出ConcurrentModificationException,因此必须捕获该异常。

Set是一种不包含重复的元素的Collection,即任意的两个元素e1和e2都有e1.equals(e2)=false,Set最多有一个null元素。

2.      提交源代码;

package test18;

 

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(20214116, "张榕", 19, "软件工程专业");

        Student s2 = new Student(20214117, "李四", 30, "材料专业");

        Student s3 = new Student(20214118, "王五", 29, "机械专业");

        Student s4 = new Student(20214119, "赵六", 34, "工商管理专业");

        Student s5 = new Student(20214120, "张三", 34, "土木专业");

        Student s6 = new Student(20214121, "孙七", 34, "电气专业");

        Student2 s7 = new Student2(20214122, "张榕", 19, "软件工程专业");

        Student2 s8 = new Student2(20214213, "李四", 30, "材料专业");

        Student2 s9 = new Student2(20214124, "王五", 29, "机械专业");

        Student2 s10 = new Student2(20214125, "赵六", 34, "工商管理专业");

        Student2 s11 = new Student2(20214126, "张三", 34, "土木专业");

        Student2 s12 = new Student2(20214127, "孙七", 34, "电气专业");

        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());

        }

    }

}

 

 

 

package test18;

 

public class Student2 implements Comparable<Student2>{

    private int studentid;

    private String name;

    private int age;

    private String major;

 

    public Student2(int studentid, String name, int age, String major) {

        super();

        this.studentid = studentid;

        this.name = name;

        this.age = age;

        this.major = major;

    }

 

    // 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

                + ". 专业: " + this.major;

    }

}

 

 

 

package test18;

 

public class Student implements Comparable<Student>{

    private int studentid;

    private String name;

    private int age;

    private String major;

 

    public Student(int studentid, String name, int age, String major) {

        super();

        this.studentid = studentid;

        this.name = name;

        this.age = age;

        this.major = major;

    }

 

    // 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

                + ". 专业: " + this.major;

    }

}

 

 

 

#include<iostream>

#include <vector>

using namespace std;

class Student{

public:

     long studentid;

     string name;

     int age;

     string major;

public:

     Student(long studentid, string name, int age, string major) {

        this->studentid = studentid;

        this->name = name;

        this->age = age;

        this->major = major;

    }

    void show(){

        cout<<"姓名: "<<this->name<<". 学号: "<<this->studentid <<". 年龄: "<< this->age<< ". 专业: " << this->major<<endl;

    }

};

bool compMax(Student *a,Student *b){

    if (a->studentid> b->studentid)

         return true;

     else

         return false;

}

bool compMin(Student *a,Student *b){

    if (a->studentid< b->studentid)

         return true;

     else

         return false;

}

int main(){

    Student *s1 = new Student(20204410, "狗蛋", 19, "软件工程专业");

    Student *s2 = new Student(20201234, "李四", 30, "材料专业");

    Student *s3 = new Student(20201564, "王五", 29, "机械专业");

    Student *s4 = new Student(20203698, "赵六", 34, "工商管理专业");

    Student *s5 = new Student(20201564, "张三", 34, "土木专业");

    Student *s6 = new Student(20204966, "孙七", 34, "电气专业");

    vector<Student*> vec;

    vec.push_back(s1);

    vec.push_back(s2);

    vec.push_back(s3);

    vec.push_back(s4);

    vec.push_back(s5);

    vec.push_back(s6);

    cout<<"按照学号从大到小输出: "<<endl;

    vector<Student*>::iterator it;

    sort(vec.begin(), vec.end(),compMax);

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

        (*it)->show();

    }

    cout<<"-----------------------------------------------------------------"<<endl;

    cout<<"按照学号从小到大输出: "<<endl;

    sort(vec.begin(), vec.end(),compMin);

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

        (*it)->show();

    }

}

3. 注意编程规范。