第三个实在不会了，请求帮助

Question

 

Answer 1

如果有帮助,望采纳! 如有任何问题,直接点头像,私信我,看到会及时回答!

 

一: 首先给你提供解决问题的思路(建议先按照这个思路自己尝试做一遍,不懂再看下面的代码)

    题目的意思涉及到的知识点有对象、集合、泛型、IO流、主要是考察你对List集合、Map集合以及IO流的使用。

    题目的考察: 如何将对象存放在List集合,如何将对象通过键值对的方式操作Mapjihe,如何接受输入流的内容!

 

二: 实现结果和代码(可直接复制运行)

 

public class Student {
    /**
     * 姓名
     */
    private String name;
    /**
     * 年龄
     */
    private Integer age;
    /**
     * 性别
     */
    private String sex;

    public String getName() {
        return name;
    }

    public Integer getAge() {
        return age;
    }

    public String getSex() {
        return sex;
    }

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

    public void setAge(Integer age) {
        this.age = age;
    }

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

    public Student(String name, Integer age, String sex) {
        this.name = name;
        this.age = age;
        this.sex = sex;
    }

    @Override
    public String toString() {
        return name + "  "+ age + "  " + sex ;
    }

    public static void main(String[] args) {
        // 3个ArrayList
        ArrayList<Student> studentListOne = new ArrayList<>();
        Student one = new Student("小明",12,"男");
        Student two = new Student("小东",22,"女");
        // 将学生放入集合
        studentListOne.add(one);
        studentListOne.add(two);

        ArrayList<Student> studentListTwo = new ArrayList<>();
        Student three = new Student("仓同学",22,"女");
        Student four = new Student("波同学",32,"女");
        // 将学生放入集合
        studentListTwo.add(three);
        studentListTwo.add(four);

        ArrayList<Student> studentListThree = new ArrayList<>();
        Student five = new Student("小同学",12,"男");
        Student six = new Student("大同学",22,"女");
        // 将学生放入集合
        studentListThree.add(five);
        studentListThree.add(six);

        // 创建键值对,K是String，value是学生集合类型
        HashMap<String, ArrayList<Student>> dataArr = new HashMap<>();

        // 添加一些学生
        dataArr.put("三年级一班",studentListOne);
        dataArr.put("三年级二班",studentListOne);
        dataArr.put("三年级三班",studentListOne);

        System.out.println("输入班级名称:");
        // 等待键盘输入
        Scanner scanner = new Scanner(System.in);
        String next = scanner.next();

        // 从Map中匹配到数据
        ArrayList<Student> list = dataArr.get(next);
        if(CollectionUtils.isEmpty(list)){
            System.out.println(next + "班级没有学生");
        } else {
            System.out.println(next + "的学生列表:");
            for (Student student : list) {
                System.out.println(student);
            }
        }

    }
}