JAVA实验四集合与函数式编程实验

前言：代码是分开写的，大家用的时候写在一个包里面就行

题目内容：

在com.experiment04.entity下，创建Student类，代码如下；

在com.experiment04.resource下，创建DatabaseUtils类，代码如下；

在com.experiment04.service下，创建StudentService接口，代码如下；

在com.experiment04.service.impl下，创建StudentService接口的实现类StudentServiceImpl，基于集合stream等操作，按接口方法注释需求实现

在com.experiment04下，创建Test类，

为每个接口方法创建静态测试方法，在main()主函数调用

面向接口编程，测试StudentService接口中方法的实现

com/experiment04/entity/Student.java

package com.experiment04.entity;

public class Student {
    public enum Sex {
        MALE, FEMALE
    }
    private int id;
    private Sex sex;
    private String name;
    // 例如2017级
    private int year;
    public Student(int id, Sex sex, String name, int year) {
        this.id = id;
        this.sex = sex;
        this.name = name;
        this.year = year;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public Sex getSex() {
        return sex;
    }

    public void setSex(Sex sex) {
        this.sex = sex;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getYear() {
        return year;
    }

    public void setYear(int year) {
        this.year = year;
    }
}

 com/experiment04/resource/DatabaseUtils.java

    package com.experiment04.resource;
    import com.experiment04.entity.Student;
    import java.util.ArrayList;
    import java.util.List;

    public class DatabaseUtils {
        private static final List STUDENTS = create();
        private static List create() {
            List students = new ArrayList<>();
            students.add(new Student(201001, Student.Sex.FEMALE, "赵阳阳", 2010));
            students.add(new Student(201002, Student.Sex.MALE, "邵鹏", 2010));
            students.add(new Student(201103, Student.Sex.MALE, "高学斌", 2011));
            students.add(new Student(201104, Student.Sex.MALE, "张扬", 2011));
            students.add(new Student(201205, Student.Sex.FEMALE, "吕惠玲", 2012));
            students.add(new Student(201206, Student.Sex.MALE, "曾志优", 2012));
            return students;
        }

        public static List getStudents() {
            return STUDENTS;
        }
    }

 com/experiment04/service/impl/StudentServiceImpl.java

package com.experiment04.service.impl;
import com.experiment04.entity.Student;
import com.experiment04.resource.DatabaseUtils;
import com.experiment04.service.StudentService;

import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;

public class StudentServiceImpl implements StudentService {

    public List addStudent(Student student) {
        List students=DatabaseUtils.getStudents();
        students.add(student);
        return students;
    }

    public List listStudentsByYear(int year) {
        List students=DatabaseUtils.getStudents();
        return students.stream()
                .filter(student -> student.getYear()==year)
                .collect(Collectors.toList());
    }

    public List listStudentsNames(int year, Student.Sex sex) {
        List students=DatabaseUtils.getStudents();
        return students.stream()
                .filter(student -> student.getYear()==year&&student.getSex()==sex)
                .map(student -> student.getName())
                .collect(Collectors.toList());
    }

    public Map> mapStudentsBySex() {
        List students=DatabaseUtils.getStudents();
        return students.stream()
                .collect(Collectors.groupingBy(student -> student.getSex()));
    }

    public boolean removeStudent(int id) {
        List students=DatabaseUtils.getStudents();
        return students.removeIf(student -> student.getId()==id);
    }
}

 com/experiment04/service/StudentService.java

package com.experiment04.service;
import com.experiment04.entity.Student;
import java.util.List;
import java.util.Map;

public interface StudentService {
    /**
     * 向集合添加一个学生，返回当前全部学生
     * @param student
     * @return
     */
    List addStudent(Student student);

    /**
     * 返回指定届的全部学生
     * @param year
     * @return
     */
    List listStudentsByYear(int year);

    /**
     * 返回指定届，指定性别的全部学生的姓名
     * @param year
     * @param sex
     * @return
     */
    List listStudentsNames(int year, Student.Sex sex);

    /**
     * 将所有学生，以性别分组
     * @return
     */
    Map> mapStudentsBySex();

    /**
     * 删除指定学号的学生，返回是否成功删除
     * @param id
     * @return
     */
    boolean removeStudent(int id);
}

 com/experiment04/Test.java

package com.experiment04;

import com.experiment04.entity.Student;
import com.experiment04.service.StudentService;
import com.experiment04.service.impl.StudentServiceImpl;

public class Test {
    private static StudentService stuSer=new StudentServiceImpl();
    public static void addStuTest() {
        Student s=new Student(1001, Student.Sex.FEMALE,"zhangsan",2016);
        System.out.println("-------addStuTest---------");
        stuSer.addStudent(s)
                .forEach(a->{
                    System.out.println(a.getId()+" "+a.getName()+" "+a.getSex()+" "+a.getYear());
                });
    }
    public static void listStudentsByYear(){
        int year=2016;
        System.out.println("-------listStudentsByYear---------");
        stuSer.listStudentsByYear(year)
                .forEach(a->{
                    System.out.println(a.getId()+" "+a.getName()+" "+a.getSex()+" "+a.getYear());
                });
    }
    public static void listStudentsNames(){
        int year=2012;
        Student.Sex sex= Student.Sex.FEMALE;
        System.out.println("-------listStudentsNames---------");
        System.out.println(stuSer.listStudentsNames(year,sex));
    }
    public static void  removeStudent(){
        int id=1001;
        System.out.println("-------removeStudent---------");
        System.out.println(stuSer.removeStudent(id));
    }
    public static void main(String[] args) {
        addStuTest();
        listStudentsByYear();
        listStudentsNames();
        removeStudent();
    }
}