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;}@Overridepublic 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);}}}
}

4 随机点名器 4

代码实现：