package com.imooc.collection;

import java.util.HashSet;

import java.util.Objects;

import java.util.Set;

/**

 * 学生类

 * Set中的元素是唯一的，不会重复，但是没有顺序。

 */

public class Student implements Comparable<Student>{



    private String id;

    private String name;

    // set集合只能使用 foreach 或 iterator进行遍历，不能使用get()来获取元素

    public Set <Course> course;

    public Student(){

    }

    public Student(String id, String name){

        this.id = id;

        this.name = name;

        this.course = new HashSet<>();

    }

    public void setId(String id) {

        this.id = id;

    }

    public void setName(String name) {

        this.name = name;

    }

    public void setCourse(Set<Course> course) {

        this.course = course;

    }

    public String getId() {

        return id;

    }

    public String getName() {

        return name;

    }

    @Override

    public boolean equals(Object o) {

        if (this == o) return true;

        if (o == null || getClass() != o.getClass()) return false;

        Student student = (Student) o;

        return Objects.equals(name, student.name);

    }

    @Override

    public int hashCode() {

        return Objects.hash(name);

    }

    public Set getCourse() {

        return this.course;

    }

    @Override

    public int compareTo(Student o) {

        // 对ID进行排序

        return this.id.compareTo(o.id);

    }

}

package com.imooc.collection;

import java.util.*;

public class SetTest {

    private final List <Course> coursesToSelect = new ArrayList<>();

    private final Scanner scanner = new Scanner(System.in);

    private Student student;

    public SetTest(){

    }

    // 用于往courseToSelect中添加备选课程

    public void testAdd(){

        // 创建一个课程对象，并通过调用add方法，添加到备选课程List中

        Course cr1 = new Course("1", "数据结构");

        coursesToSelect.add(cr1);

        Course cr2 = new Course("2", "C语言");

        coursesToSelect.add(0, cr2);

        // Course数组

        Course[] course = {new Course("3", "离散数学"), new Course("4", "汇编语言")};

        coursesToSelect.addAll(Arrays.asList(course));

        Course[] course2 = {new Course("5", "高等数学"), new Course("6", "大学英语")};

        coursesToSelect.addAll(2, Arrays.asList(course2));

    }

    /**

     * 通过 foreach 方法来遍历List

     */

    public void testForeach(){

        // System.out.println("(foreach)有如下课程待选：");

        for (Object obj: coursesToSelect) {

            Course cr = (Course) obj;

            System.out.println("课程：" + cr.getId() + "：" + cr.getName());

        }

    }

    /**

     * 遍历Student集合中的所有元素

     * @param student

     */

    public void testForeachSet(Student student){

        // 打印学生所选课程

        for(Course cr: student.course) {

            System.out.println("选择了课程:" + cr.getId() + ":" + cr.getName());

        }

    }

    /**

     * 测试List的 contains 方法

     * @param

     */

    public void testListContainers(){

        // 获取备选课程序列的第0个元素

        Course course = coursesToSelect.get(0);

        // 打印输出coursesToSelected是否包含course对象

        System.out.println("取得课程：" + course.getName());

        System.out.println("备选课程中是否包含课程：" + course.getName() + "," + coursesToSelect.contains(course));

        // 提示输入课程名称

        System.out.println("请输入课程名称：");

        String name = scanner.next();

        Course course2 = new Course();

        course2.setName(name);

        // 创建一个新的课程对象, ID和名称 与course对象完全一样

        // Course course2 = new Course(course.getId(), course.getName());

        System.out.println("新创建课程对象：" + course2.getName());

        System.out.println("备选课程中是否包含课程：" + course2.getName() + ","+ coursesToSelect.contains(course2));

        // 通过indexOf()方法来获取某元素的索引位置

        if(coursesToSelect.contains(course2)){

            System.out.println("课程：" + course2.getName() + "的索引位置为：" + coursesToSelect.indexOf(course2));

        }

        coursesToSelect.sort(new Comparator<Course>() {
　　　　　　　// 重写compare方法　

            @Override

            public int compare(Course o1, Course o2) {

                if(Integer.parseInt(o1.getId()) > Integer.parseInt(o2.getId())){

                    return 0;

                }

                return -1;

            }

        });

        for(Course cr: coursesToSelect){

            System.out.println("课程ID:" + cr.getId() + "课程名称:" + cr.getName());

        }

    }public static void main(String args[]){

        SetTest st = new SetTest();

        st.testAdd();

        st.testForeach();

        st.testListContainers();

    }

}