NEFU-2023-JAVA实验四

迷南。 2024-04-17 11:43 57阅读 0赞

题目

> 创建实验项目工程java-experiments  
> 在com.experiment04.entity下，创建Student实体类。包含，id，姓名，性别等属性。（附件中已给出）  
> 在com.experiment04.resource下，创建DatabaseUtils类，添加模拟若干对象（附件中已给出）
> 
> 在com.experiment04.service下，StudentService接口中已声明基于集合流操作的方法（附件中已给出）
> 
> 在com.experiment04.service.impl下，创建StudentService接口的实现类StudentServiceImpl，**基于****传统的集合操作和集合****stream操作****两种方法（其中addStudent(）方法用一种方法实现，删除可以有传承的迭代器实现，或者直接用removeIf()方法实现）****，**按接口方法注释需求实现
> 
> 理解项目的包结构
> 
> 在com.experiment04下，创建Test类  
> 为每个接口方法创建静态测试方法，在主函数调用  
> 面向接口编程，测试StudentService接口中方法的实现
> 
> （1）程序上交，只需要上交StudentServiceImpl类的每个方法实现（除了 addStudent(）方法，其他方法用两种方法实现）及Test类中对每个方法的测试代码（测试类只写一个就可以，添加学生信息时添加自己的个人信息）。
> 
> （2）运行结果截图。
> 
> （3）说明实验中出现的问题及解决办法，写出实验的心得体会。

### com/experiment04/entity/Student.java ###

package com.experiment04.entity;
    
    public class Student {
        public enum Sex {
            MALE, FEMALE
    
        }
        private int id;//学生证
        private Sex sex;//性别
        private String name;//名字
        // 例如2017级
        private int year;//入学年份
        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 java.util.ArrayList;
    import java.util.List;
    import com.experiment04.entity.Student;
    
    
    
    public class DatabaseUtils {
    
        private static final List<Student> STUDENTS = create();
    
        private static List<Student> create() {
    
            List<Student> 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<Student> getStudents() {
            return STUDENTS;
    
        }
    
    }

### com/experiment04/service/StudentService.java ###

package com.experiment04.service;
    
    
    import java.util.List;
    
    import java.util.Map;
    
    import com.experiment04.entity.Student;
    
    
    
    public interface StudentService {
    
        /**
    
         * 向集合添加一个学生，返回当前全部学生
    
         * @param student
    
         * @return
    
         */
    
        List<Student> addStudent(Student student);
    
        /**
    
         * 返回指定届的全部学生
    
         * @param year
    
         * @return
    
         */
    
        List<Student> 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<String> listStudentsNames(int year, Student.Sex sex);
    
    
    
        /**
    
         * 将所有学生，以性别分组
    
         * @return
    
         */
    
        Map<Student.Sex, List<Student>> 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/service/impl/StudentServiceImpl.java ###

使用普通方法

package com.experiment04.service.impl;
    
    import java.util.*;
    import java.util.stream.Collectors;
    
    import com.experiment04.entity.Student;
    import com.experiment04.entity.Student.Sex;
    import com.experiment04.resource.DatabaseUtils;
    import com.experiment04.service.StudentService;
    public class StudentServiceImpl implements StudentService{
        @Override
        public List<Student> addStudent(Student student) {
            // TODO Auto-generated method stub
            List<Student> students=DatabaseUtils.getStudents();
            students.add(student);
            return students;
        }
    
        @Override
        public List<Student> listStudentsByYear(int year) {
            List<Student> students = DatabaseUtils.getStudents();
            List<Student> result = new ArrayList<>();
            for (Student student : students) {
                if (student.getYear() == year) {
                    result.add(student);
                }
            }
            return result;
        }
        @Override
        public List<String> listStudentsNames(int year, Sex sex) {
            List<Student> students = DatabaseUtils.getStudents();
            List<String> result = new ArrayList<>();
            for (Student student : students) {
                if (student.getYear() == year && student.getSex() == sex) {
                    result.add(student.getName());
                }
            }
            return result;
        }
        @Override
        public Map<Sex, List<Student>> mapStudentsBySex() {
            List<Student> students = DatabaseUtils.getStudents();
            Map<Sex, List<Student>> result = new HashMap<>();
            for (Student student : students) {
                Sex sex = student.getSex();
                if (!result.containsKey(sex)) {
                    result.put(sex, new ArrayList<>());
                }
                result.get(sex).add(student);
            }
            return result;
        }
        @Override
        public boolean removeStudent(int id) {
            List<Student> students = DatabaseUtils.getStudents();
            for (Iterator<Student> iterator = students.iterator(); iterator.hasNext();) {
                Student student = iterator.next();
                if (student.getId() == id) {
                    iterator.remove();
                    return true;
                }
            }
            return false;
        }
    
    }

使用流方法

package com.experiment04.service.impl;
    
    import java.util.ArrayList;
    import java.util.List;
    import java.util.Map;
    import java.util.stream.Collectors;
    
    import com.experiment04.entity.Student;
    import com.experiment04.entity.Student.Sex;
    import com.experiment04.resource.DatabaseUtils;
    import com.experiment04.service.StudentService;
    public class StudentServiceImpl implements StudentService{
    	@Override
    	public List<Student> addStudent(Student student) {
    		// TODO Auto-generated method stub
    		List<Student> students=DatabaseUtils.getStudents();
    		students.add(student);
    		return students;
    	}
    
    	@Override
    	public List<Student> listStudentsByYear(int year) {
    		// TODO Auto-generated method stub
    		List<Student> students = DatabaseUtils.getStudents();
    		return students.stream()
    				.filter(student -> student.getYear()== year)
    				.collect(Collectors.toList());
    	}
    	@Override
    	public List<String> listStudentsNames(int year, Sex sex) {
    		// TODO Auto-generated method stub
    		List<Student> students = DatabaseUtils.getStudents();
    		return students.stream()
    				.filter(student -> student.getYear() == year && student.getSex() == sex)
    				.map(Student::getName)
    				.collect(Collectors.toList());
    	}
    	@Override
    	public Map<Sex, List<Student>> mapStudentsBySex() {
    		// TODO Auto-generated method stub
    		List<Student> students = DatabaseUtils.getStudents();
    		return students.stream()
    				.collect(Collectors.groupingBy(student -> student.getSex()));
    	}
    	@Override
    	public boolean removeStudent(int id) {
    		// TODO Auto-generated method stub
    		List<Student> students = DatabaseUtils.getStudents();
    		return students.removeIf(student -> student.getId() == id);
    	}
    
    }

### com/experiment04/Test.java ###

package com.experiment04;
    
    import java.util.*;
    import java.util.stream.Collectors;
    
    import com.experiment04.entity.*;
    import com.experiment04.resource.*;
    import com.experiment04.service.impl.*;
    
    public class Test {
    	public static StudentServiceImpl t=new StudentServiceImpl();
    	public static void addTest(){
    		Student student = new Student(201207, Student.Sex.MALE,"高喜乐",2002);
    		System.out.println("-------addStudent测试-----------");
    		t.addStudent(student)
    				.forEach(a->{
    					System.out.println("ID: "+a.getId()+" "+"性别: "+a.getSex()+" "+"姓名: "+a.getName()+" "+"入学年份: "+a.getYear());
    				});
    	}
    	public static void listStudentsByYearTest(){
    		System.out.println("-------listStudentsByYearTest测试-----------");
    		t.listStudentsByYear(2010)
    				.forEach(a->{
    					System.out.println("ID: "+a.getId()+" "+"性别: "+a.getSex()+" "+"姓名: "+a.getName()+" "+"入学年份: "+a.getYear());
    				});
    	}
    
    	public static void listStudentsNamesTest(){
    		System.out.println("-------listStudentsNamesTest测试-----------");
    		System.out.println(t.listStudentsNames(2012,Student.Sex.FEMALE));
    	}
    	public static void printList(List<Student> list){
    		for (Student s : list) {
    			System.out.print(s.getId() + " " + s.getName());
    			if (s.getSex() == Student.Sex.FEMALE) System.out.print(" 女");
    			else System.out.print(" 男");
    			System.out.println(s.getYear());
    		}
    
    	}
    	public static void mapStudentsBySexTest(){
    		System.out.println("-------mapStudentsBySexTest测试-----------");
    		Map<Student.Sex, List<Student>> map=t.mapStudentsBySex();
    		List<Student> list=map.get(Student.Sex.MALE);
    		printList(list);
    		list=map.get(Student.Sex.FEMALE);
    		printList(list);
    	}
    
    	public static void removeStudentTest(){
    		System.out.println("-------mapStudentsBySex测试-----------");
    		t.removeStudent(201205);
    		List<Student> students = DatabaseUtils.getStudents();
    		for (Student a : students) {
    			System.out.println("ID: " + a.getId() + " " + "性别: " + a.getSex() + " " + "姓名: " + a.getName() + " " + "入学年份: " + a.getYear());
    		}
    
    	}
    	public static void main(String[] args) {
    		//addTest();
    		//listStudentsByYearTest();
    		//listStudentsNamesTest();
    		//mapStudentsBySexTest();
    		removeStudentTest();
    	}
    }