当处理一个CSV字符串空决赛场上，myString.split（＆QUOT;，＆QUOT;）返回数组项的数量不正确 [英] When processing a csv String with an empty final field, myString.split( "," ) returns incorrect number of array entries

问题描述

我在处理某行从.csv文件中读取使用 String.split（）并找到最终的空字符串后，最后一个分隔符是不使它成为了拆分创建数组的功能。

I'm processing a certain line read from a .csv file using String.split(",") and finding that the final empty string after the last delimiter is not making it into the array created by the split function.

下面是导致该错误的变量值：

Here are the variable values that are causing the error:

String toSplit = "1,Some Value,31337,Another Value,";
String[] values = toSplit.split( "," );

在值阵列最终具有比数组项的预计数较少。创建数组是：

The values array ends up having fewer than the expected count of array entries. The array created is:

values[0] : '1'
values[1] : 'Some Value'
values[2] : '31337'
values[3] : 'Another Value'

与值[4] 抛出ArrayIndexOutOfBounds异常情况。

with a values[4] throwing an ArrayIndexOutOfBounds exception.

我想该数组是：

values[0] : '1'
values[1] : 'Some Value'
values[2] : '31337'
values[3] : 'Another Value'
values[4] : ''

警告：我读的另一.csv文件创建者的输出，并且不希望使用字符串分隔符或抛出一个'空白字符，如果相应的数据是空的地方。 （即不希望： toSplit =1，一定的价值，31337，另一种价值，用空格​​就结束）

One caveat: I am reading the output of another .csv file creator and don't want to use string delimiters or throw a ' ' whitespace character into places where the data is empty. (ie. do not want: toSplit = "1,Some Value,31337,Another Value, " with whitespace on the end.)

这是在String.split（错误），是有一种变通方法/另一种选择？

Is this a bug in String.split() and is there a workaround/another option?

推荐答案

想通了，因为我是进入的问题！使用 stringObj.split（，numDelimitersExpected）或，作为@Supericy指出， stringObj.split（，，-1）

Figured it out as I was entering the question! Use stringObj.split( ",", numDelimitersExpected ) or, as @Supericy pointed out, stringObj.split( ",", -1 ).

据有关<一个Android的文档href="http://developer.android.com/reference/java/util/regex/Pattern.html#split%28java.lang.CharSequence%29"相对=nofollow> stringObj.split（分隔符）调用 line.split（）相当于调用 line.split（，0）的第二个参数指的是限制，这台'的最大的数项的，并定义了治疗尾随空字符串的。看着对文件<一个href="http://developer.android.com/reference/java/util/regex/Pattern.html#split%28java.lang.CharSequence%29"相对=nofollow> stringObj.split（分隔符）它指出与限制== 0 结尾空字符串将不予退还

According to the Android docs about stringObj.split( delimiter ) a call to line.split( "," ) is equivalent to a call to line.split( ",", 0 ) with the second argument referring to limit, which sets the 'maximum number of entries' and defines the 'treatment of trailing empty strings' . Looking at the documentation for stringObj.split( delimiter ) it states that with limit == 0 'trailing empty strings will not be returned'.

该解决方案是使用调用拆分（，限）与限制设置为您希望数组项的数量找回。在我的情况下，限制设置为5返回数组

The solution is to use a call to split( ",", limit ) with limit set to the number of array entries you expect to get back. In my case a limit set to 5 returns the array

values[0] : '1'
values[1] : 'Some Value'
values[2] : '31337'
values[3] : 'Another Value'
values[4] : ''

这正是我想要的。 问题解决了。

事实上，即使你的 toSplit 字符串比限制少分隔符，有一组<调用code>限制仍然会创建空数组项高达限制。例如，与相同的输入字符串在我的问题：

In fact, even if your toSplit string has less delimiters than limit, a call with a set limit will still create empty array entries up to limit. For example, with the same input string as in my question:

String toSplit = "1,Some Value,31337,Another Value,"

呼叫字符串值[] = toSplit.split（，，8）返回数组

values[0] : '1'
values[1] : 'Some Value'
values[2] : '31337'
values[3] : 'Another Value'
values[4] : ''
values[5] : ''
values[6] : ''
values[7] : ''

整齐！

注：Oracle的Java的 String.split（分隔符）具有相同的功能与Android的文档赢得他们的更简洁的解释。 （：

Note: Oracle's Java String.split( delimiter ) has the same functionality with the Android docs winning for their more concise explanation. (:

编辑：作为@Supericy增加， toSplit.split（，，-1）也要正确返回尾随空条目。感谢您的加入！

As @Supericy added, toSplit.split( ",", -1 ) would also properly return the trailing empty entry. Thanks for the addition!

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