Question

   public static void userClass() throws IOException
   String data="";
    String classroom="";
    System.out.println("Please enter the class");
    classroom = sc.nextLine().toLowerCase();
    String subject=classroom.toUpperCase();
    boolean match=false;
    BufferedReader input = new BufferedReader(new FileReader("data.txt"));
    data = input.readLine();
    Scanner scanner = new Scanner(System.in);
    data = input.readLine();
    int subjectIndex = 10;
    String items[]=new String [11]; // rows
    while(data!=null)
    {
        data=input.readLine();
        if (data==null)
            break; 
        items=data.split(",");
        for (int x=0; x<items.length; x++)
        {
            if (items.length>10)
            {
                if (items[10].contains(classroom))
                {
                    match=true;
                }
            }
        }
    }
    if (match==true)
    {
        System.out.println("There are " + items[0] + "," + items[1]+  "(" +items[2]+ ")" + " student's enrolling in" +classroom);
    }
    else if (match==false)
    {
        System.out.println("The subject " +subject+ " is not taught at our school");
    }

所有注册用户指定课程的学生

这是我尝试过这两个问题，但我一直在收到错误ArraylangIndexBoundException :10。

Answer 1

您在userClass（）中将项目声明为10个元素的字符串数组，然后您尝试使用该行访问其第11个元素

java.util.Arrays.toString(items[10].split("(?<=\\G.......)"));

Answer 2

String items[]=new String [10];
boolean match = false; 
int count=0;

这一行总是会失败，因为Java数组从0开始，所以items [9]是最大值

java.util.Arrays.toString(items[10].split("(?<=\\G.......)"));

此外，所有数组元素都是空的。

Answer 3

在您的文件中，您有11个元素，因此您的作业应该是：
```
String items[]=new String [11];
```
虽然它没有必要，但您可以在以下代码中看到：

您不需要最后一列的数组。您只需使用.contains方法来确定用户输入的字符串是否在最后一列中。

BufferedReader input = new BufferedReader(new FileReader("data.txt"));
int count=0;    
while ((data = input.readLine()) != null) {
    String[] items = data.split(",");
    if (items[10].toLowerCase().contains(subject)) {
        System.out.println("There students in enrolling in "  +classroom+ " are " +items[0]+ " " + items[1] + " (" + items[2] + ")");
        count++;            
    }
}
if (count==0)
{
    System.out.println("There subject " + classroom+ " is not taught at our school");
}

编辑： 3.如果要使用布尔变量，则代码看起来像。

boolean match=false;
while(data!=null)
{
    data=input.readLine();
    if (data==null)
        break;
    items=data.split(",");
    if (items[10].toLowerCase().contains(subject)) {
        System.out.println("There students in enrolling in "  +classroom+ " are " +items[0]+ " " + items[1] + " (" + items[2] + ")");
        match=true;           
    }
}
if (!match)
{
    System.out.println("There subject " + classroom+ " is not taught at our school");
}

Answer 4

试试这个

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.util.Scanner;

public class ReadFile {

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


        Scanner scanner = new Scanner(System.in);
        String classroom = scanner.nextLine().toLowerCase();
        BufferedReader input = new BufferedReader(new FileReader("data.txt"));
        String data = input.readLine();
        int subjectIndex = 10;
        String[] items = new String[0];
        boolean match=false;
        while (data != null) {
            items = data.split(",");

            if (items.length > 10) {
                if (items[subjectIndex].toLowerCase().contains(classroom)) {
                    System.out.println("There students in enrolling in "  +classroom+ " are " +items[0]+ " " + items[1] + " (" + items[2] +")");
                    match = true;
                }
            }
            data = input.readLine();
        }

        if(!match)
        {
            System.out.println("The subject " +classroom+ " is not taught at our school");
        }

    }
}

输入

AWQ2O0ECHC2D0ECHV2O0BENG2D0DFSF2D0AGLC2O0BMPM2D0APPL2OMBSNC2D0C

输出

There students in enrolling in awq2o0echc2d0echv2o0beng2d0dfsf2d0aglc2o0bmpm2d0appl2ombsnc2d0c are Amath Brandon (522442)
 There are 1 students in awq2o0echc2d0echv2o0beng2d0dfsf2d0aglc2o0bmpm2d0appl2ombsnc2d0c

文件处理比较字符串和文本文件

4 个答案: