Random类

 1 import java.util.Random;
 2 import java.util.Scanner;
 3 
 4 public class RandomPractice {
 5     public static void main(String[] args) {
 6         Scanner scanner = new Scanner(System.in);
 7         Random random = new Random();
 8         int index = random.nextInt(101);
 9         while (true) {
10             System.out.print("请输入0-100的数字：");
11             int n = scanner.nextInt();
12             if (n > index) {
13                 System.out.println("输入的数字过大");
14             } else if (n < index) {
15                 System.out.println("输入的数字过小");
16             } else {
17                 System.out.println("输入正确");
18                 break;
19             }
20         }
21         System.out.println("游戏结束！");
22     }
23 }