For 循环打印到文件永远加载并且文件空白，即使关闭？

Question

我正在尝试编写代码，通过从 10 中选择一个随机数来模拟 1000 多次试验的蒙特卡洛方法，直到数字为 10，然后每次都会增加（观察到的松鼠数量）的计数器，直到随机数数字是 10；然后这个计数器将被打印到一个文件中。然而，这是通过在 in 中嵌套循环的 For 循环完成的，但程序似乎在此 For 循环中永远加载一次，并且即使使用了 close() 文件也保持空白。

import java.io.IOException;

import java.io.PrintWriter;

import java.io.File;

import java.util.Scanner;

import java.util.Random;

public class AnimalPopulation

{

    public static void main(String[] args) throws IOException

    {

    //declare and initialize variables

    Random randsquirrel = new Random();

    Scanner in = new Scanner(System.in);

    PrintWriter outFile = new PrintWriter(new File ("squirreldata.txt"));

    // User input

    System.out.println("Welcome to the Fox Squirrel Simulator");

    System.out.println("\n");

    System.out.println("How many trials should be simulated?");

    System.out.println("Enter a value greater than 1000:");

    int trialcounter = in.nextInt();

    // Input does not match requirements

    while (trialcounter <= 1000)

    {

        System.out.print("\n\n  Please try again. Enter a number greater than 1000.");

        System.out.println();

        System.out.println("How many trials should be simulated?");

        System.out.println("Enter a value greater than 1000:");

        trialcounter = in.nextInt();

    }

    System.out.println("\nsimulating trials now... one moment please ...");

    // Experiment with ratio of 1/10 fox squirrels 

    int randomsquirrel = 0;

    int totalsquirrels = 0;

    for (int i = 1; i <= trialcounter; i++)

    {

        randomsquirrel = randsquirrel.nextInt(10)+1;

            while (randomsquirrel != 10)

            {

                totalsquirrels++;

            }

                if (randomsquirrel == 10);

                {

                    totalsquirrels++;

                }

        outFile.println(totalsquirrels);

    }

Answer 1

你能告诉我这里有什么问题吗？&nbsp; &nbsp; randomsquirrel = randsquirrel.nextInt()+1;&nbsp; &nbsp; while (randomsquirrel != 10)&nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; totalsquirrels++;&nbsp; &nbsp; }While 循环由 3 个部分组成：while 关键字、(condition) 和 {lines to run}while (condition) {&nbsp; &nbsp; //lines to run.}首先检查条件是否轮到它将执行所有要运行的行。完成所有行后，它会再次检查条件。如果条件仍然为真，它将再次运行所有行。它将永远运行这些线路，直到条件变为假或遇到中断为止。

Answer 2

您使用不正确的 while 因为您永远不会更改 while 循环中的值，这会导致无限循环。正确的方法：public static void main(String[] args) throws IOException{&nbsp; &nbsp; SecureRandom randsquirrel = new SecureRandom(); // it is better&nbsp; &nbsp; // rest of your code&nbsp; &nbsp; int randomsquirrel = 0;&nbsp; &nbsp; int totalsquirrels = 0;&nbsp; &nbsp; for (int i = 1; i <= trialcounter; i++)&nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; randomsquirrel = randsquirrel.nextInt(10)+1;&nbsp; &nbsp; &nbsp; &nbsp; while (randomsquirrel != 10)&nbsp; &nbsp; &nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; randomsquirrel = randsquirrel.nextInt(10) + 1:&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; totalsquirrels++;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; if (randomsquirrel == 10);&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; break;&nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp; &nbsp; }&nbsp; &nbsp; // rest of your code}