集合课后练习

练习1

 

练习2

package JUL.JUL.Jul17;

import java.util.*;

public class Demo01 {
    static Scanner input = new Scanner(System.in);

    // 创建数组
    public List addList(String[] strs) {
        List<String> list = new ArrayList<String>();
        for (int i = 0; i < strs.length; i++) {
            list.add(strs[i]);
        }
        return list;
    }

    public static void main(String[] args) {
        Map<String, List> map = new HashMap<String, List>();
        String[] str1 = {"A1", "A2", "A3"};
        String[] str2 = {"B1", "B2", "B3"};
        String[] str3 = {"C1", "C2", "C3"};
        Demo01 demo01 = new Demo01();
        List<String> list1 = demo01.addList(str1);
        List<String> list2 = demo01.addList(str2);
        List<String> list3 = demo01.addList(str3);

        map.put("一班", list1);
        map.put("二班", list2);
        map.put("三班", list3);

        System.out.println("请输入班级名：");
        String name = input.next();

        List<String> l = map.get(name);
        Iterator<String> iterator = l.iterator();

       for (int i= 0;i<l.size();i++){
           if(iterator.hasNext()){
               System.out.println(iterator.next()+"\n");
           }
       }
    }
}

 练习3

package JUL.JUL.Jul17;

public class Student {
    private String name;
    private int age;
    private String sex;

    public Student() {
    }

    public Student(String name, int age, String sex) {
        this.age = age;
        this.name = name;
        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 JUL.JUL.Jul17;

import java.util.*;

public class TestStudent {
    static Scanner input = new Scanner(System.in);
    public static void main(String[] args) {
        List<Student> list1 = new ArrayList<Student>();
        List<Student> list2 = new ArrayList<Student>();
        List<Student> list3 = new ArrayList<Student>();
        for (int i = 1; i <= 5; i++) {
            Student stu1 = new Student("张" + i, 18, "男");
            Student stu2 = new Student("李" + i, 18, "男");
            Student stu3 = new Student("王" + i, 28, "女");
            list1.add(stu1);
            list2.add(stu2);
            list3.add(stu3);

        }
        HashMap<String,List<Student>> has = new HashMap<String,List<Student>>();
        has.put("一班",list1);
        has.put("二班",list2);
        has.put("三班",list3);
        System.out.println("请输入班级名：");
        String name = input.next();
        List<Student> list = has.get(name);
        System.out.println(name+"学生列表：");
        for(Student st:list){
            System.out.println(st.getName()+"\t"+st.getAge()+"\t"+st.getSex());
        }


    }
}