java 集合练习题2（配有实例代码）

Posted 2022-12-03 施莱

java 集合练习题2（配有实例代码）

**问题：3.编写Java程序，创建学员类Student,并添加姓名、年龄、性别等字段，创建3个ArrayList<T>对象， 指定T为Student 类，每个ArrayList<T> 中添加一些学员对象，
再创建HashMap<K,V> 对象，以年级名称为键，指定为String 类型，指定value 类型为
ArayList<Student>， 值为存放学员的ArrayList<T>对象，然后从HashMap<K,V>对象
中获取某个班级的学员信息并输出。**   

package shiYan;

public class Student 

    String name;
    int age;
    String sex;


    public Student() 
    

    public Student(String name, int age, String sex) 
        this.name = name;
        this.age = age;
        this.sex = sex;
    

    public String getName() 
        return name;
    

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

    public int getAge() 
        return age;
    

    public void setAge(int age) 
        this.age = age;
    

    public String getSex() 
        return sex;
    

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

package shiYan;

import ZuoYe.Student1;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;

public class Test 

    public static void main(String[] args) 
        ArrayList<Student> student1 = new ArrayList<>();
        ArrayList<Student> student2 = new ArrayList<>();
        ArrayList<Student> student3 = new ArrayList<>();

        Student stu1 = new Student("ewh0", 20, "男");
        Student stu2 = new Student("ewh01", 21, "男");
        Student stu3 = new Student("ewh02", 22, "男");


        Map<String, ArrayList<Student>> hashMap = new HashMap<>();

        student1.add(stu1);
        student1.add(stu2);
        student1.add(stu3);

        String key1="三年级一班";

        hashMap.put(key1, student1);

        Scanner scanner = new Scanner(System.in);
        System.out.println("输入班级名称：");
        String s = scanner.nextLine();
        System.out.println(s+"学生列表");

        ArrayList<Student> students = hashMap.get(key1);

        for (Object value:students)
            Student student=(Student)value;
            System.out.println(student.getName()+"   "+student.getSex()+"   "+student.getAge());
        

    


运行结果
输入班级名称：
三年级一班
三年级一班学生列表
ewh0   男   20
ewh01   男   21
ewh02   男   22

进程已结束，退出代码 0