在控制台中显示来自文本文件的信息

Question

我正在开发一个 Java 程序，该程序的行为应该类似于“虚拟寻宝游戏”，基本上它随机遍历数字，直到找到与您正在寻找的动物相匹配的数字，然后显示结果。该信息应该存储在一个文件中，然后显示在控制台中，但它只是在我单击运行时终止。我认为存在某种逻辑错误，因为我没有得到任何有关语法的信息。

import java.io.IOException; 
import java.io.PrintWriter;
import java.io.File;
import java.util.Scanner; 
public class AnimalPopulation {

public static void main(String[] args) throws IOException
{
    // TODO Auto-generated method stub

    int totalTrials = 0;
    int animalsSpotted = 0; 
    double randNum = 0;
    double myAnimal = 4.0;
    double notMyAnimal = 0; 
    String data = "int";

    Scanner in = new Scanner(System.in);
    Scanner inFile = new Scanner ("animals.txt");

    PrintWriter outFile = new PrintWriter(new File("animals.txt"));
    //BufferedReader in = new BufferedReader(new FileReader("animals.txt"));

System.out.println("How many trials will you be running? (It must be greater than or equal to 1,000.)");
totalTrials = in.nextInt();

    while(animalsSpotted < totalTrials) {
        animalsSpotted++; 
        randNum = (1 + (Math.random()* 9));

        if(randNum < myAnimal) {

            outFile.println(notMyAnimal++);
        }else if(randNum > myAnimal) {

            outFile.println(notMyAnimal++);
        }else if(randNum == myAnimal) {

            outFile.println(myAnimal++);


            while(inFile.hasNext()) {

                data = inFile.next();
                System.out.println(data);
            }

            inFile.close();



        }


    }

outFile.close();
}

}

Answer 1

第一件事是您必须将 randNum 更改为 int 并使用ThreadLocalRandom 如答案中所述，另一件事首先将所有数据写入文件然后读取它不要并行执行操作，这是一个程序以你为例：

import java.io.*;
import java.util.Scanner;
import java.util.concurrent.ThreadLocalRandom;

public class AnimalPopulation{
   public static void main(String[] args) throws IOException {
       // TODO Auto-generated method stub

    int totalTrials = 0;
    int animalsSpotted = 0;
    int randNum = 0;
    double myAnimal = 4.0;
    double notMyAnimal = 0;
    String data = "int";

    Scanner in = new Scanner(System.in);

    PrintWriter outFile = new PrintWriter(new File("animals.txt"));
    //BufferedReader in = new BufferedReader(new FileReader("animals.txt"));

    System.out.println("How many trials will you be running? (It must be greater than or equal to 1,000.)");
    totalTrials = in.nextInt();

    while(animalsSpotted < totalTrials) {
        animalsSpotted++;
        randNum = ThreadLocalRandom.current().nextInt(1,11);

        if(randNum < myAnimal) {

            outFile.println(notMyAnimal++);
        }else if(randNum > myAnimal) {

            outFile.println(notMyAnimal++);
        }else if(randNum == myAnimal) {

            outFile.println(myAnimal++);
        }
    }
    outFile.close();
    File file = new File("animals.txt");

    BufferedReader br = new BufferedReader(new FileReader(file));

    String st;
    while ((st = br.readLine()) != null)
        System.out.println(st);
}
}

Answer 2

randNum 是 double 和 (1 + (Math.random()* 9)) 产生 1 到 10 之间的一些小数值，因此它极不可能等于 4.0。相反，您可能希望将类型更改为 int 并使用 ThreadLocalRandom.current().nextInt(1,11) 生成介于 1 和 10 之间的值。