Question

我已经制作了一段代码，用于读取包含此信息的csv文件。它包含学生姓名和考试成绩。

Christopher Lee，54.0

Stanley Wright，90.5

Oliver Stewart，75.8

Jessica Chang，34.65

在文件中读取时，文件名由用户输入为String。文件的内容必须同时存储在两个数组中，其中学生名称将存储为字符串，测试标记将存储为实数。我有一个选择菜单，有两个选项，显示标记和退出。当选择“显示标记”时，用户输入学生的名称，程序在数组中找到名称的索引号，然后程序打印出相同的索引号但在包含测试标记的数组中，从而打印出来相应的测试标记。

我已经完成了大部分代码，但我需要一些帮助来排除故障并修复IO逻辑。我是文件IO的新手。感谢

以下是代码：

import java.util.*;
import java.io.*;

public class MarksIO
{

    public static void main(String[] args)
    {
        Scanner sc = new Scanner(System.in);
        String fileName;

        fileName = sc.nextLine();
        boolean valid;
        valid = false;
        while (valid)
        {
            int choice = 0;
            System.out.println("Select an Option: ");
            System.out.println("Display Mark = 1.\nExit = 2.");
            if (choice == 1)
            {
                System.out.println("Enter the name of the Student.");
                String name;
                name = sc.nextLine();
                int lines = getNumLines(fileName);
                String[] arrayString = new String[lines];
                double[] arrayReal = new double[lines];
                readFile(arrayString, arrayReal, fileName);
                System.out.println("Test Mark is: " + arrayReal[index]);
            }
            else if (choice == 2)
            {
                System.exit(0);
            }
        }

    }

    public static int indexCalc(String name, double[] arrayReal,
            String[] arrayString)
    {
        for (int index = 0; index < arrayString.length; index++)
        {
            if (arrayString[index].equals(name))
            {
                return index;
            }
        }
    }

    public static void readFile(String fileName, double[] arrayReal,
            String[] arrayString)
    {
        FileInputStream fileStream = null;
        InputStreamReader reader;
        BufferedReader bufferedReader;
        int lineNum;
        String line;

        try
        {
            fileStream = new FileInputStream(fileName);
            reader = new InputStreamReader(fileStream);
            bufferedReader = new BufferedReader(reader);

            for (int i = 0; i <= arrayString.length; i++)
            {
                lineNum = 0;
                line = bufferedReader.readLine();
                while (line != null)
                {
                    lineNum++;
                    arrayString[i] = processString(line);
                    arrayReal[i] = processReal(line);
                }
            }
            fileStream.close();
        }
        catch (IOException ex)
        {
            if (fileStream != null)
            {
                try
                {
                    fileStream.close();
                }
                catch (IOException ex2)
                {

                }
                System.out.println("Error in file processing: "
                        + ex.getMessage());
            }

        }

    }

    public static String processString(String line, String[] arrayString)
    {
        String[] stringArray = line.split(",");
        String string = stringArray[0];
        return string;
    }

    public static double processReal(String line, double[] arrayReal)
    {
        double[] realArray = line.split(",");
        double real;
        real = (double)(realArray[1]);
        return real;

    }

    public static int getNumLines(String fileName)
    {
        FileInputStream fileStream;
        InputStreamReader reader;
        BufferedReader bufferedReader;
        try
        {
            fileStream = new FileInputStream(fileName);
            reader = new InputStreamReader(fileStream);
            bufferedReader = new BufferedReader(reader);
        }
        catch (FileNotFoundException e)
        {
            System.out.println("Error in file processing: " + e.getMessage());
        }
        int numLines;
        numLines = 0;
        int lineNum = 0;
        String line = bufferedReader.readLine();
        while (line != null)
        {
            lineNum++;
            numLines = numLines + 1;
            line = bufferedReader.readLine();

        }

    }

}

Answer 1

您可以使用Scanner类完成此任务。喜欢

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

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

        Scanner s = null;

        try {
            s = new Scanner(new BufferedReader(new FileReader("xanadu.txt")));

            while (s.hasNext()) {
                System.out.println(s.next());
            }
        } finally {
            if (s != null) {
                s.close();
            }
        }
    }
}

文件IO帮助 - 读入

1 个答案: