将csv文件读入数组后获取OutOfBounds异常[重复]

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How to avoid ArrayIndexOutOfBoundsException or IndexOutOfBoundsException? [duplicate] 2 answers

如何避免ArrayIndexOutOfBoundsException或IndexOutOfBoundsException? [重复] 2个答案

I'm writing a program that takes a csv file, and reads each of the lines into an array of USCrimeClass objects that have their own field. I want to see if the arrays are being made correctly by printing one of them out, but I am getting an OutOfBounds exception.

我正在编写一个带有csv文件的程序,并将每行读入一个具有自己字段的USCrimeClass对象数组。我想通过打印其中一个来查看阵列是否正确,但我得到一个OutOfBounds异常。

import java.io.*;
import java.util.*;
public class USCrimeClass
{
    public int year;
    public int population;
    public int violentCrime;
    public double violentCrimeRate;
    public int manslaughter;
    public double manslaughterRate;
    public int rape;
    public double rapeRate;
    public int robbery;
    public double robberyRate;
    public int assault;
    public double assaultRate;
    public int propertyCrime;
    public double propertyCrimeRate;
    public int burglary;
    public double burglaryRate;
    public int larcenyTheft;
    public double larcenyTheftRate;
    public int vehicleTheft;
    public double vehicleTheftRate;

    public USCrimeClass(String line)
    {
        String[]split=line.split(",");
        year=Integer.parseInt(split[0]);
        population=Integer.parseInt(split[1]);
        violentCrime=Integer.parseInt(split[2]);
        violentCrimeRate=Double.parseDouble(split[3]);
        manslaughter=Integer.parseInt(split[4]);
        manslaughterRate=Double.parseDouble(split[5]);
        rape=Integer.parseInt(split[6]);
        rapeRate=Double.parseDouble(split[7]);
        robbery=Integer.parseInt(split[8]);
        robberyRate=Double.parseDouble(split[9]);
        assault=Integer.parseInt(split[10]);
        assaultRate=Double.parseDouble(split[11]);
        propertyCrime=Integer.parseInt(split[12]);
        propertyCrimeRate=Double.parseDouble(split[13]);
        burglary=Integer.parseInt(split[14]);
        burglaryRate=Double.parseDouble(split[15]);
        larcenyTheft=Integer.parseInt(split[16]);
        larcenyTheftRate=Double.parseDouble(split[17]);
        vehicleTheft=Integer.parseInt(split[18]);
        vehicleTheftRate=Double.parseDouble(split[19]);
    }

    public static void main(String[] args)
    {
        Scanner read = null;
        {
            try
            {
                read=new Scanner(new File("C:\\Crime.csv"));
            }
            catch(FileNotFoundException e)
            {
                System.out.println("The file can't be opened");
                System.exit(0);
            }



            String[] lines = null;

            read.nextLine();
            while(read.hasNextLine())
            {
                lines=read.nextLine().split(",");
            }

            USCrimeClass[] CrimeYear=new USCrimeClass[lines.length];

            for(int i=0;i<lines.length;i++)
            {
                CrimeYear[i]=new USCrimeClass(lines[i]);
            }
            read.close();

            System.out.println(CrimeYear[0]);
        }
    }
}

Here is what the csv file should look like

这是csv文件应该是什么样子

1994,260327173,1130,3.7,3890,39.5,...
1995,250692382,2478,21.5,2230,28.6,...
1996,230492492,4092,22.8,3202,39.4...

And here is the error message

这是错误信息

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 1
at USCrimeClass.<init>(USCrimeClass.java:30)
at USCrimeClass.main(USCrimeClass.java:84)

1 个解决方案

#1

Regarding this code:

关于这段代码:

while(read.hasNextLine())
{
    lines = read.nextLine().split(",");
}

what you are doing here is reading the file line by line, but you are always overwriting lines with the currently read line. In the end lines will only contain the split contents of the last line and not all lines in the csv file.

你在这里做的是逐行读取文件,但你总是用当前读取的行覆盖行。在结束行中只包含最后一行的拆分内容,而不包含csv文件中的所有行。

Add each read line to a list and then this should work:

将每个读取行添加到列表中,然后这应该工作:

List<String> lines = new ArrayList<>();

read.nextLine();
while(read.hasNextLine())
{
    lines.add(read.nextLine());
}

USCrimeClass[] CrimeYear = new USCrimeClass[lines.size()];

for(int i=0;i<lines.size();i++)
{
    CrimeYear[i]=new USCrimeClass(lines.get(i));
}
read.close();

In case you don't want to buffer all the read lines, you can also directly create the corresponding objects:

如果您不想缓冲所有读取行,您还可以直接创建相应的对象:

List<USCrimeClass> crimeClasses = new ArrayList<>();
read.nextLine();
while(read.hasNextLine())
{
    crimeClasses.add(new USCrimeClass(read.nextLine()));
}

read.close();

System.out.println(crimeClasses.get(0));

BTW: I'd also recommend putting the read.close() into a finally { ... } block.

顺便说一句:我还建议将read.close()放入finally {...}块。

#1