Question

我目前有一些可以接受控制台输入的代码，但我需要让它识别名称和测试分数列表。我目前拥有的代码：

import java.io.*;
import utils.io.*;

class student
{
   String name;
   double sResult[];
   int result;
   double sum;

   void getdata()
   {
      System.out.println("Enter name:");
      Name = (string) system.in.read();
      int index=0;

      for (int counter=1; counter<=5; counter++)
      {
         System.out.println("Enter result for subject"+counter+":");
         sResult[count] = (double) system.in.read();
      }
   }

   public static void CalculateAverage()
   {
      sum = 0;
      for (int i=1;i<=5;i++)
      {
         sum += sResult[i];
      }
      return (int) Math.round(sum/(values.length-1));
   }

   Public static char calculateGrade()
   {
      result=sum;
      if (result>=0 && result <=59)
      {
         return ('F');
      }
      else
      if (result >=60 && result<=69)
      {
         return ('E');
      }
      else
      if (result>=0 && result<79)
      {
         return ('D');
      }
      else
      if (result >=70 && result<=79)
      {
         return ('C');
      }
      else
      if (result>=80 && result<=89)
      {
         return ('B');
      }
      else
      if (result>=90 && result<=100)
      {
         return ('A');
      }
   }
}

和班级考试

public class test
{
   public static void main(String[] args)
{
   Student std;
   do
   {
      std=new Student();
      std.getdata();
      System.out.println("Student Name:"+std.Name);
      System.out.println("Average for"+std.Name+" "+"is:"+std.average());
      System.out.println("Grade for"+std.Name+" "+"is:"+std.gradecal());
      System.out.println("Want to continue (1-Yes,2-No");
   }
   while(System.in.read()==1);
}

文本文档格式为name score1 score2 score3 score4 score5

我只需要帮助搞清楚如何导入值，然后我就可以弄清楚如何使用PrintWriter重写.txt。

提前感谢您的帮助！

Answer 1

首先，你不应该有以大写字母开头的变量名，即：

string Name;

只有班级名称应以大写字母开头。

另外，我甚至不确定你的代码是否编译。您system.out.println所在的任何地方都应该是System.out.println。请注意，System是一个类，因此第一个字母是大写

要阅读数据，您可以使用BufferedReader进行编写，您可以使用BufferedWriter。用法：

BufferedReader in = new BufferedReader(new FileReader("FileName.txt"));
BufferedWriter out = new BufferedWriter(new FileWriter("OutputFileName.txt"));

in.readLine(); //This reads a single line from the text file
out.write("Your Output Text");
in.close(); // Closes the file input stream
out.close(); // Closes the file output stream

因为您正在阅读以下格式：

名称得分1得分2得分3得分4得分5

你可以使用一些String函数来获取每个字段。

String inputLine = in.readLine();
String [] fields = inputLine.split(" "); // Splits at the space
System.out.println(fields[0]); //prints out name
System.out.println(fields[1]); //print out score1
...

Answer 2

以下是Scanner的使用方法。

Scanner inputFile = new Scanner(new File("inputfile.txt"));
while(inputFile.hasNext()){ //if there is still something to read
     String name = inputFile.next();
     int score1 = inputFile.nextInt();    
     ....
     int score5 = inputFile.nextInt();
     //Do something here with the scores
     inputFile.next(); //Read the new line character and prepare for the next iteration 
}

要写回文件，您可以查看Davy的答案并使用Buffered Writer。请注意，write()方法的工作方式与System.out.println()类似，但您需要自行打印\n才能转到新行。

Answer 3

public static void main(String... args) throws IOException {
    Scanner s = new Scanner(new BufferedReader(new FileReader("textfile.txt")));
    while(s.hasNext()){
        Student student = new Student(s.next(), s.nextDouble(), s.nextDouble(),
                                      s.nextDouble(), s.nextDouble(), s.nextDouble() ));
        // Do something with student
        s.next() // consume endline
    }
}

如何从Java中的.txt文件中提取信息？

3 个答案: