Java学习笔记 黑马微项目二

1 随机点名器 1

代码实现：

import java.util.ArrayList;
import java.util.Random;
import java.util.Scanner;

public class shu20_1 {
    public static void main(String[] args) {
        ArrayList<String> list = new ArrayList<>();
        Scanner sc = new Scanner(System.in);
        System.out.println("需要添加多少个学生");
        int n = sc.nextInt();
        sc.nextLine();
        while (n-- > 0) {
            System.out.println("输入学生姓名：");
            String s = sc.nextLine();
            list.add(s);

        }

        System.out.println(list);
        Random rand = new Random();
        int i = rand.nextInt(list.size());
        String s = list.get(i);
        System.out.println(s);
    }
}

注意事项

2 随机点名器 2

代码实现：

public class Students {
    private String name;
    private String sex;

    public Students(String name, String sex) {
        this.name = name;
        this.sex = sex;
    }

    public Students() {
    }

    public String getName() {
        return name;
    }

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

    public String getSex() {
        return sex;
    }

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

    @Override
    public String toString() {
        return "姓名:"+name+" 性别:"+sex;
    }
}

方法调用：

import itheima.shu20.s5.Students;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Random;
import java.util.Scanner;

public class shu20_2 {
    static Scanner input = new Scanner(System.in);

    public static void main(String[] args) {
        System.out.println("这是一个学生点名系统");
        System.out.println("请输入学生人数");
        int a = input.nextInt();
        input.nextLine();
        //定义三个集合分别存储学生，男学生，女学生
        ArrayList<Students> s = new ArrayList<>();
        ArrayList<Students> s1 = new ArrayList<>();
        ArrayList<Students> s2 = new ArrayList<>();
        while (a-- > 0) {
            Students students = new Students();
            System.out.printf("输入姓名 %d号：", 3 - a);
            students.setName(input.nextLine());
            System.out.printf("输入性别 %d号：", 3 - a);
            students.setSex(input.nextLine());
            System.out.println();
            s.add(students);
        }
        for (int i = 0; i < s.size(); i++) {
            if (s.get(i).getSex().equals("男")) {
                s1.add(s.get(i));
            } else {
                s2.add(s.get(i));
            }
        }
        System.out.println(s);

        ArrayList<Integer> list = new ArrayList<>();
        Collections.addAll(list, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0);
        Collections.shuffle(list);
        Integer i = list.get(0);
        Random r = new Random();
        if (i == 0) {
            int i2 = r.nextInt(s2.size());
            Students students = s2.get(i2);
            System.out.println("最后点了" + students);
        } else {
            int i1 = r.nextInt(s1.size());
            Students students = s1.get(i1);
            System.out.println("最后点了" + students + "同学");
        }


    }
}

3 随机点名器 3

代码实现：

import java.util.ArrayList;
import java.util.Random;
import java.util.Scanner;

public class shu20_3 {
    static Scanner input = new Scanner(System.in);

    public static void main(String[] args) {
        System.out.println("下面是一个点名器");
        System.out.print("输入学生人数：");
        int n = input.nextInt();
        input.nextLine();
        ArrayList<String> list0 = new ArrayList<>();
        ArrayList<String> list1 = new ArrayList<>();
        while (n-- > 0) {
            list0.add(input.nextLine());
        }
        Random r = new Random();
        while (!list0.isEmpty()) {
            System.out.println("输入1 开始点名 \n输入2 退出");
            if (input.nextInt() == 1) {
                int i = r.nextInt(list0.size());
                System.out.println("点到了" + list0.get(i));
                System.out.println();
                //原集合删除元素，另一个集合添加进去
                list1.add(list0.get(i));
                list0.remove(i);
                //如果集合中的人全点完了，那就将两个集合互换进行下一轮操作
                if (list0.isEmpty()) {
                    list0 = new ArrayList<>(list1);
                    list1 = new ArrayList<>(list0);
                }
            } else {
                System.exit(0);
            }
        }
    }
}