如何避免在解析一行CSV中的空位置时触发ArrayIndexOutOfBoundsException？ [英] How to avoid triggering an ArrayIndexOutOfBoundsException while parsing empty positions in a line of CSV?

问题描述

String[] values = line.split(",");

Long locId = Long.parseLong(replaceQuotes(values[0]));
String country = replaceQuotes(values[1]);
String region = replaceQuotes(values[2]);
String city = replaceQuotes(values[3]);
String postalCode = replaceQuotes(values[4]);
String latitude = replaceQuotes(values[5]);
String longitude = replaceQuotes(values[6]);
String metroCode = replaceQuotes(values[7]);
String areaCode = replaceQuotes(values[8]);

//...

public String replaceQuotes(String txt){
    txt = txt.replaceAll("\"", "");
    return txt;
}

我使用上面的代码来解析CSV格式的数据格式为：

I'm using the code above to parse a CSV with data in this format:

828,"US","IL","Melrose Park","60160",41.9050,-87.8641,602,708

但是，当我遇到一行数据时， java.lang.ArrayIndexOutOfBoundsException：7

However, when I encounter a line of data such as the following I get java.lang.ArrayIndexOutOfBoundsException: 7

1,"O1","","","",0.0000,0.0000,,

这是否意味着任何时候我甚至尝试访问 values [7] 的值，将抛出异常？

Does this mean that any time I even try to access the value at values[7], an Exception will be thrown?

如果是这样，我如何解析不包含文本行那个位置的数据的行？

If so, how do I parse lines that don't contain data in that position of the text line?

推荐答案

首先， String.split（）不是一个伟大的CSV解析器：它不知道报价，并会搞砸，只要你的一个引用值包含一个逗号。

First of all, String.split() is not a great CSV parser: it doesn't know about quotes and will mess up as soon as one of your quoted values contains a comma.

话虽如此，默认情况下 String.split（） 不包含空的尾部元素。您可以使用双参数变量：

That being said, by default String.split() leaves out empty trailing elements. You can influence that by using the two-argument variant:

String[] values = line.split(",", -1);

• -1


• 使用正值可以得到最大分割数（意思是除此之外的所有数据都将被分配）单个值，即使它包含逗号）。


• 0 （如果使用单参数值，则为默认值）数组将根据需要增大，但是空的尾随值将被排除在数组之外（正如你碰到的那样）。


• -1 (or any negative value) means that the array will be as large as necessary.
• Using a positive value gives a maximum amount of splits to be done (meaning that everything beyond that will be a single value, even if it contains a comma).
• 0 (the default if you use the one-argument value) means that the array will be as large as necessary, but empty trailing values will be left out of the array (exactly as it happens to you).

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