每个switch语句块结束一定要加 ;  不然会出出现 fall through 的问题

System.out.println("please choice:");

System.out.println(" 1: 石头");

System.out.println(" 2: 剪刀");

System.out.println(" 3: 布");

Scanner scanner = new Scanner(System.in); // 创建Scanner对象

System.out.print("Input your choice: "); // 打印提示

int choice = scanner.nextInt(); // 读取一行输入并获取字符串

if (choice<1 || choice>3) {

System.out.println("wrong choice");

}

// 计算机随机数 1, 2, 3:

int random = 1 + (int) Math.random() * 3;

System.out.println("Random Number:"+random);

switch (choice) {

case 1 ->{

switch (random) {

case 1 -> System.out.println("平手");

case 2 -> System.out.println("You win");

case 3 -> System.out.println("You lose");

default -> System.out.println("default");};

}

case 2 ->{

switch (random) {

case 1 -> System.out.println("You lose");

case 2 -> System.out.println("平手");

case 3 -> System.out.println("You Win");

default -> System.out.println("default");};

}

case 3 ->{

switch (random) {

case 1 -> System.out.println("You Win");

case 2 -> System.out.println("You lose");

case 3 -> System.out.println("平手");

default -> System.out.println("default");};

}

default -> System.out.println("Default");

};