java - 错误 :Exception in thread "main" java. lang.ArrayIndexOutOfBoundsException:0

Question

运行代码时出现此错误:

线程“main”中出现异常 java.lang.ArrayIndexOutOfBoundsException: 0 在 Module11_13_RealWorldProblem.main(Module11_13_RealWorldProblem.java:194)

我不知道如何解决它。我有一个文本文档，它应该读取该文档以获取信息，但它没有运行。

import java.io.File;

import java.io.FileWriter;

import java.io.IOException;

import java.io.PrintWriter;

import java.nio.file.Files;

import java.nio.file.Paths;

import java.util.ArrayList;

import java.util.List;

import java.util.Scanner;

class User

{

private final String id;

private final String lstName;

private final String FstName;

private final String addressLine1;

String addressLine2;

private final String City;

private final String State;

private final long zip;

long zipPlus4;

private final double payAmount;

private final String payDate;

private final double payDue;

public User(String id,String lstName,String fstName,

String addressLine1,String addressLine2,String City,

String State,long zip,long zipPlus4,

String payDate,double payAmount,double payDue)

{

this.id=id;

this.lstName=lstName;

this.FstName=fstName;

this.addressLine1=addressLine1;

this.addressLine2=addressLine2;

this.City=City;

this.State=State;

this.zip=zip;

this.zipPlus4=zipPlus4;

this.payAmount=payAmount;

this.payDate=payDate;

this.payDue=payDue;

}

public void setAddLine2(String add){

this.addressLine2=add;}

public void setZipPlus4(long zip){

this.zipPlus4=zip;}

public long getZip()

{

return zip;

}

public double getPayAMount()

{

return payAmount;

}

public double getDueAMount()

{

return payDue;

}

public String getDate()

{

return payDate;

}

public String getaddressLine1()

{

return addressLine1;

}

public String getaddressLine2()

{

return addressLine2;

}

public String getCity()

{

return City;

}

public String getState()

{

return State;

}

public String getlstName()

{

return lstName;

}

public String getId()

{

return id;

}

public String getfstName()

{

return FstName;

}

public long getZipPlus4(){

return zipPlus4;}

}

public class Module11_13_RealWorldProblem {

public static void main(String[] args){

List<User> lst=new ArrayList<User>();


Scanner in=new Scanner(System.in);

File file = new File(args[0]);

if (!file.exists()) {

System.out.println(args[0] + " does not exist.");

return;

}

if (!(file.isFile() && file.canRead())) {

System.out.println(file.getName() + " cannot be read from.");

return;

}

try {

List<String> allLines = Files.readAllLines(Paths.get(args[0]));

for (String line : allLines) {

//System.out.println(line);

String[] str=line.split("\\^");

User user=new User(str[0],str[1],str[2],

str[3],"".equals(str[4])?"NoValue":str[4],str[5],str[6],

Long.valueOf(str[7]),"".equals(str[8])?Long.MAX_VALUE:Long.valueOf(str[8]),

str[9],Double.valueOf(str[10]),Double.valueOf(str[11]));

lst.add(user);

}

} catch (IOException e) {

e.printStackTrace();

}

System.out.println("Do opertauiosn,");

System.out.println("Do you want to output the report to the screen ('S'), to a file ('F') or both ('B')");

String ch=in.nextLine();

StringBuilder sb=new StringBuilder();

for (User user : lst) {

sb.append(user.getId()+"^"+user.getlstName()+","+user.getfstName()+"^"+user.getaddressLine1()

+"^"+("NoValue".equals(user.getaddressLine2())?"":user.getaddressLine2())+"^"+user.getCity()+"^"+user.getState()+"^"+user.getZip()+"^"+(

Long.MAX_VALUE==user.getZipPlus4()?"":user.getZipPlus4())

+"^"+user.getPayAMount()+"^"+user.getPayAMount()+"^"+user.getDueAMount());

sb.append("\n");

}

if("S".equalsIgnoreCase(ch))

{

System.out.println(sb.toString());

}

else if("F".equalsIgnoreCase(ch))

{

System.out.println("Enter output file name with full path");

String outputFilename=in.nextLine();

log(sb.toString(),outputFilename);

System.out.println("File successfully written");

}

else if("B".equalsIgnoreCase(ch))

{

System.out.println(sb.toString());

System.out.println("Enter output file name with full path");

String outputFilename=in.nextLine();

log(sb.toString(),outputFilename);

System.out.println("File successfully written");

}

}

public static void log(String message,String fName){

try {

PrintWriter out = new PrintWriter(new FileWriter(fName, true), true);

out.write(message);

out.close();

} catch (Exception e) {

System.out.print("There is something wrong in output file/file path..retry !");

}



}

}

生成报告时跳过那些不属于报告格式的字段重新排列不同顺序的字段，使其符合报告格式向用户添加提示“您要将报告输出到屏幕('S')、文件('F')还是两者('B')”。如果用户输入“S”，您的代码应该像当前一样在屏幕上显示报告。用户输入大写字母还是小写字母都无关紧要。例如“S”或“s”应该不重要。在这两种情况下，用户都应按上述方式显示数据。如果用户输入“F”(或“f”)，那么应用程序应该提示用户输入所需的文件名(包括文件路径)使用用户输入的文件名/路径将报告输出到文件。如果发送到屏幕，此输出的格式应与报告完全相同，只是它将报告输出到文件。如果用户输入“B”(或“b”)，则应用程序应将报告输出到屏幕并将其输出到文件。

Answer 1

程序在运行程序时需要来自命令行的输入。

File file = new File(args[0]);

args 是一个空数组，抛出一个indexOutOfBoundException。

确保在运行程序时传递文件名。