无法从Java文件中读取数据

Question

我正在用Java代码从一个文本文件读取数据并将数据打印到另一个文本文件中。我没有任何错误，但是运行时显示没有输入，而我得到的只是输出和一个空文件（在printwriter文件中）。但是，我非常确定我使用扫描仪读取的文件中有输入。

 Process finished with exit code 0

这是我的代码：

import java.io.*;
import java.util.Scanner;
public class ASSI4 {
    public static void main(String[] args) {
        try {
            Scanner kbd = new Scanner(new File("st.txt"));
            PrintWriter nbb = new PrintWriter((new File("res.txt")));
            long[] ID = new long[30];
            double[][] CM = new double[30][6];
            while (kbd.hasNextLine()) {
                for (int i = 0; i < 30; i++) {
                    String line = kbd.nextLine();
                    String[] arr = line.split("\t");
                    ID[i] = Long.parseLong(arr[0]);

                    {
                        CM[i][0] = Double.parseDouble(arr[1]);
                        CM[i][1] = Double.parseDouble(arr[2]);
                        CM[i][2] = Double.parseDouble(arr[3]);
                        CM[i][3] = Double.parseDouble(arr[4]);
                        CM[i][4] = Double.parseDouble(arr[5]);
                        CM[i][5] = Double.parseDouble(arr[6]);
                    }
                }

                for (int i = 0; i < 30; i++) {
                    double sumA = 0;
                    for (int j = 0; j < 6; j++) {
                        sumA = sumA + CM[i][j];
                    }
                    double avg = sumA / 6;
                    avg = Math.round(avg * 100.0) / 100.0;
                    nbb.println(ID[i] + "  " + CM[i][0] + "  " + CM[i][1] + "  " + CM[i][2] + "  " + CM[i][3] + "  " + CM[i][4] + "  " + CM[i][5] + " " + avg);
                }
            }
            nbb.close();
            kbd.close();


        }
        catch (Exception e) {
            e.getMessage();
        }
    }
}

这是我的st.txt文件：

20186966 90.0 55.8 98.0 67.9 46.0 77.1
20185978 32.0 19.8 49.8 67.0 86.4 46.0
20189409 53.8 79.0 84.6 39.9 74.5 27.0
20183970 39.7 88.0 78.6 66.0 25.4 0.0
20190291 36.9 32.8 10.0 46.8 21.5 65.9 
20196949 99.0 47.6 36.7 85.5 82.9 77.0
20173040 46.8 40.9 30.5 95.9 94.9 99.8 
20171679 55.7 29.0 99.8 36.8 69.0 80.6 
20175747 77.0 100.0 56.7 36.9 34.8 22.9 
20190850 84.0 85.5 68.8 81.7 83.9 57.8 
20193406 20.0 44.5 50.0 18.6 30.9 77.8 
20175802 71.9 80.0 60.8 99.9 31.0 87.9 
20184693 46.0 94.9 58.7 73.0 35.7 29.5
20185769 76.9 67.8 51.8 12.6 96.0 94.0
20181274 28.9 85.9 76.6 42.9 32.0 95.9
20194284 1.0 44.8 75.6 44.8 33.9 30.6
20175501 70.9 24.5 48.8 80.5 76.8 61.9
20198125 6.0 16.0 12.9 25.0 3.0 29.6
20194027 33.0 27.7 83.9 31.0 75.0 74.9
20179253 87.0 100 22.9 68.9 14.8 98.0
20172010 94.0 93.9 31.9 100 70.8 90.0
20177254 11.0 26.5 2.6 30.8 86.0 100.0
20184917 60.9 24.3 49.6 61.9 66.0 80.9
20181322 83.0 45.3 74.5 64.5 50.0 99.7
20196820 78.0 75.0 70.9 56.9 99.0 19.9
20196734 35.4 34.9 84.8 68.0 15.9 70.0
20192018 91.0 59.5 3.4 42.9 81.0 58.8
20178007 55.9 94.8 71.5 38.0 81.7 98.0
20173948 93.0 100.0 9.8 45.7 47.0 9.9
20192749 26.0 45.0 57.4 95.9 14.4 79.0

Answer 1

问题：

您使用了\t而不是\\s+。我们应该使用\\s+来匹配空白字符：[ \t\n\x0B\f\r]。选中this以了解有关模式的更多信息。

旁注：

1. 按照Java naming conventions例如ID应命名为id，CM应命名为cm。
2. 请勿将读取与写入混合使用，即读取源文件并关闭它，然后写入目标文件并关闭它。
3. 用e.getMessage();或至少e.printStackTrace();替换System.out.println(e.getMessage());。>>

解决方案：

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

public class ASSI4 {
    public static void main(String[] args) {
        try {
            Scanner kbd = new Scanner(new File("st.txt"));
            long[] id = new long[30];
            double[][] cm = new double[30][6];
            while (kbd.hasNextLine()) {
                for (int i = 0; i < 30; i++) {
                    String line = kbd.nextLine();
                    String[] arr = line.split("\\s+");
                    id[i] = Long.parseLong(arr[0]);
                    cm[i][0] = Double.parseDouble(arr[1]);
                    cm[i][1] = Double.parseDouble(arr[2]);
                    cm[i][2] = Double.parseDouble(arr[3]);
                    cm[i][3] = Double.parseDouble(arr[4]);
                    cm[i][4] = Double.parseDouble(arr[5]);
                    cm[i][5] = Double.parseDouble(arr[6]);
                }
            }
            kbd.close();

            PrintWriter nbb = new PrintWriter((new File("res.txt")));
            for (int i = 0; i < 30; i++) {
                double sumA = 0;
                for (int j = 0; j < 6; j++) {
                    sumA = sumA + cm[i][j];
                }
                double avg = sumA / 6;
                avg = Math.round(avg * 100.0) / 100.0;
                nbb.println(id[i] + "  " + cm[i][0] + "  " + cm[i][1] + "  " + cm[i][2] + "  " + cm[i][3] + "  "
                        + cm[i][4] + "  " + cm[i][5] + " " + avg);
            }
            nbb.close();

        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}