为什么从java中的文件读取int阵列时会引发异常

Question

我正在尝试从文件中读取整数数组。文件格式如下：

893

410

243

264

357

33

793

...

...

我稍后将该数组拆分为4并使用MPI计算它的总和，但我似乎无法读取该文件。我得到这个异常：

java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at runtime.starter.MulticoreStarter$1.run(MulticoreStarter.java:281)
at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.NumberFormatException: For input string: "893"
at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
at java.lang.Integer.parseInt(Integer.java:580)
at java.lang.Integer.parseInt(Integer.java:615)
at lab3.main(lab3.java:28)
... 6 more

Process finished with exit code 0

所以根据我的理解，读取字符串的格式不正确，无法转换为整数，这里是代码：

        //create an array of length 400
        int[] array = new int[400];

        //read the array from the file using the scanner class
        try {
            Scanner scanner = new Scanner(new File("random1000.txt"));
            for (int i = 0; i < array.length; i++) {
                array[i] = Integer.parseInt(scanner.nextLine());

            }
        }
        catch (FileNotFoundException e) {
            System.out.println("File not found");
        }

我还尝试了 scanner.nextInt() 和 Integer.valueof() 而不是 parseInt，这是我在 scanner.nextInt() 中遇到的错误

java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at runtime.starter.MulticoreStarter$1.run(MulticoreStarter.java:281)
at java.lang.Thread.run(Thread.java:748)
Caused by: java.util.InputMismatchException
at java.util.Scanner.throwFor(Scanner.java:864)
at java.util.Scanner.next(Scanner.java:1485)
at java.util.Scanner.nextInt(Scanner.java:2117)
at java.util.Scanner.nextInt(Scanner.java:2076)
at lab3.main(lab3.java:30)
... 6 more

这是我第一次使用 Scanner 类，而且我对 java 还很陌生，我做错了什么我该如何解决这个问题？

这是完整的代码，我还没有测试任何 mpi 的东西，但我尝试在没有 mpi 代码的情况下读取文件，并且遇到了同样的问题。

import mpi.*;

import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;

public class lab3 {


//Build a program that sums a big array (for example 1000 elements) over four processes
public static void main(String[] args) {

    //initialize MPI
    MPI.Init(args);

    //get the rank of the process
    int rank = MPI.COMM_WORLD.Rank();

    //if the rank is 0
    if (rank == 0) {
        // read the array from the file
        int[] array = new int[400];

        //read the array from the file using file reader
        try {
            Scanner scanner = new Scanner(new File("random1000.txt"));
            for (int i = 0; i < array.length; i++) {
                array[i] = scanner.nextInt();

            }
        }
        catch (FileNotFoundException e) {
            System.out.println("File not found");
        }


        //divide the array into 4 parts and send it to the other processes
        int[] array1 = new int[array.length / 4];
        int[] array2 = new int[array.length / 4];
        int[] array3 = new int[array.length / 4];
        int[] array4 = new int[array.length / 4];
        for (int i = 0; i < array.length / 4; i++) {
            array1[i] = array[i];
            array2[i] = array[i + array.length / 4];
            array3[i] = array[i + array.length / 2];
            array4[i] = array[i + array.length / 4 + array.length / 2];
        }
        //send each part to the other processes
        MPI.COMM_WORLD.Send(array2, 0, array2.length, MPI.INT, 1, 0);
        MPI.COMM_WORLD.Send(array3, 0, array3.length, MPI.INT, 2, 0);
        MPI.COMM_WORLD.Send(array4, 0, array4.length, MPI.INT, 3, 0);

        //calculate the sum of the array 1
        int sum1 = 0;
        for (int i = 0; i < array1.length; i++) {
            sum1 += array1[i];
        }

        //receive the summation from the other processes
        int sum2 = 0;
        MPI.COMM_WORLD.Recv(sum2 ,0, 0, MPI.INT, 1, 0);
        int sum3 = 0;
        MPI.COMM_WORLD.Recv(sum3 ,0, 0, MPI.INT, 2, 0);
        int sum4 = 0;
        MPI.COMM_WORLD.Recv(sum4 ,0, 0, MPI.INT, 3, 0);

        //calculate the final sum
        int sum = sum1 + sum2 + sum3 + sum4;

        //print the final sum
        System.out.println("The Final sum is: " + sum);

        //finalize MPI
        MPI.Finalize();
    }
    else {
        //receive the array from the process 0
        int[] array = new int[1000 / 4];
        MPI.COMM_WORLD.Recv(array, 0, array.length, MPI.INT, 0, 0);

        //calculate the sum of the array
        int sum = 0;
        for (int i = 0; i < array.length; i++) {
            sum += array[i];
        }

        //send the sum to the process 0
        MPI.COMM_WORLD.Send(sum, 0, 0, MPI.INT, 0, 0);
        //print local sum and rank
        System.out.println("The sum of the array is: " + sum + " and the rank is: " + rank);
    }
}


}

IntelliJ Idea，Windows 11。

编辑：

我尝试这样做：

List<Integer> ints = Files.lines(Paths.get("random1000.txt"))
                    .map(Integer::parseInt)
                    .collect(Collectors.toList());
array = ints.stream().mapToInt(i -> i).toArray();

抛出java.lang.NumberFormatException：对于输入字符串：“893”

Answer 1

我创建了一个新文件，并手动添加了一些随机数，据我了解，我用来创建文本文件的随机数生成器可能在开始时添加了一些额外的字节，这可能是问题的原因。