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NullPointer 异常，无法使用 BufferedReader 调用 String.split [关闭]

[英]NullPointer Exception, Cannot invoke String.split with BufferedReader [closed]

原文 2022-02-06 00:59:27 4 0 java/ csv/ nullpointerexception/ bufferedreader

我目前正在为课程编写一段代码，它涉及从 CSV 文件中获取数据，获取该信息并让用户知道哪些打印机墨水不足。 当我尝试像这样调用 String.split 方法时，我不断收到此错误消息，告诉我我的 String 行为空

import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class Reader {
    private static final String COMMA_DELIMITER = ",";
    public static void main(String[] args) throws IOException {
    //String path = "D:/MiniProjectToner.csv";


    BufferedReader reader = null;
    try{
        reader = new BufferedReader(new FileReader("D:/MiniProjectToner.csv"));
        String lines= "";
        List<Printer> printerList = new ArrayList<Printer>();
        List<Printer> printerLow = new ArrayList<Printer>();
        reader.readLine();




       while((lines = reader.readLine()) != null);
        {
            String[] printer =lines.split(COMMA_DELIMITER);


            if(printer.length > 0){
                Printer printObj = new Printer(printer[0],printer[1],printer[2],printer[3],Integer.parseInt(printer[4]),
                        Integer.parseInt(printer[5]),Integer.parseInt(printer[6]));
                printerList.add(printObj);


            }
            else{
                Printer printLowWarn = new Printer(printer[0], printer[3],Integer.parseInt(printer[4]),Integer.parseInt(printer[5]));
                printerLow.add(printLowWarn);
            }
            for (Printer f : printerLow){

                System.out.println(f.getPrinterName()+ " " + f.getSerialNumber() + "" + f.getBlackCart() + " " + f.getColorCart());
            }
            for(Printer e : printerList)
            {
                System.out.println(e.getPrinterName()+" " + e.getIpAddress()+ " " +e.getLastComment()+ " " +e.getSerialNumber()+ " "
                        +e.getBlackCart() +" " +e.getColorCart()+ " " +e.getPageCount());
            }

        }

它说它在第 30 行（String[] 打印机 = lines.split(COMMA_DELIMITER)。

在弄乱它的同时，我注意到当我使该错误消失时，它给了我另一个错误，说索引 1 超出了长度 1 的范围。任何帮助将不胜感激！