如何将用户限制为仅输入 1-3

Question

import java.util.Random;
import java.io.*;
import java.util.*;
/**
    Courtney Fox 
    Professor Yao
    Midterm Part 1
    10/10/17
    Purpose:
      The purpose of this program is to develop a Nim game that consists of a
      pile of stones ranging from 10-16. From that pile, both the player and 
      computer have to pick up to 3 stones and whoever gets the last stone 
      loses. 
   Logic:
**/   
public class FoxMidQ1
{
   public static void main(String[] args)
   {
      //Variables
      int user = 0;
      //int computer;
      //int loser;
      int gamenum = 0;
      //Scanner
      Scanner input = new Scanner(System.in);
     //Welcome Output
     System.out.println("Welcome to Nim Game!");
     //Get pile size: Randomly generate 10-16
     int[] pile = {10, 11, 12, 13, 14, 15 , 16};
     int stones = pile[(int)(Math.random() * pile.length)];
     System.out.println("Game #"+ (gamenum + 1) +": There are "+ stones + " 
     stones in the pile.");
     System.out.println("You can remove up to 3 stones from pile at a 
     time.");
     //User takes stones
     System.out.println("How many stones would you like to remove? ");
     user = input.nextInt();

我开始了，但我被困在用户只应该从堆中取出 1、2 或 3 块石头的部分。我尝试做 do，while，for，if，else，这些循环都没有做我想让它做的事情，因为用户只假设有一个回合，然后是计算机轮到从堆中捡起最多 3 块石头。

Answer 1

在这里，您正在从用户那里获取输入

 System.out.println("How many stones would you like to remove? ");
 user = input.nextInt();

输入后，只需比较值，如果它在 1 和 3 之间，则提示更正，如果它不在 1 和 3 之间，

则只需显示一条消息，说"输入应该在 1 和 3 之间"。

if(user >0 && user <= 3) {
  //do the needful
} else {
  //Print the custom message saying that wrong input
}

Answer 2

在user = input.nextInt();之后添加这个

boolean testForCorrectInput = true;
while(testForCorrectInput)
{
      if(user < 1 || user >3)
      {
           System.out.println("nWrong input. Please enter a number between 1 and 3");
           user = input.nextInt();    
      }
      else
           testForCorrectInput = false;
 }

这将测试用户是否输入了正确的输入，并提示他们输入该输入，直到输入了介于 1 和 3 之间的值。