Java的String的split方法忽略空字符串 [英] Java String's split method ignores empty substrings

问题描述

今天发生在我的java的行为 String.split（）是很奇怪的。

It occured to me today the behavior of java String.split() is very strange.

其实我想要分割字符串AA，BB，CC，DD ,,, EE来阵列由 .split（ ）这给了我一个String数组 [AA，BB，抄送，DD，，，EE] 长7。

Actually I want to split a string "aa,bb,cc,dd,,,ee" to array by .split(",") that gives me a String array ["aa","bb","cc","dd","","","ee"] of length 7.

但是当我尝试拆分字符串AA，BB，CC，DD ,,,,来排列这给了我一个长度为4的数组只是意味着 [AA，BB，抄送，DD] 拒绝所有一个空白字符串。

But when I try to split a String "aa,bb,cc,dd,,,," to array this gives me a array of length 4 means only ["aa","bb","cc","dd"] rejecting all next blank Strings.

我要那个分裂像AA，BB，CC，DD ,,,,来阵列 [AA的字符串的程序，BB，抄送，DD，，，] 。

I want a procedure that splits a String like "aa,bb,cc,dd,,,," to array ["aa","bb","cc","dd","","",""].

这可能与java.lang.String中的API？先谢谢了。

Is this possible with java.lang.String api? Thanks in advance.

推荐答案

使用<一个href=\"http://docs.oracle.com/javase/7/docs/api/java/lang/String.html#split%28java.lang.String,%20int%29\"><$c$c>String.split(String正则表达式，INT限制） 负限制（例如-1）。

Use String.split(String regex, int limit) with negative limit (e.g. -1).

"aa,bb,cc,dd,,,,".split(",", -1)

在<一个href=\"http://docs.oracle.com/javase/7/docs/api/java/lang/String.html#split%28java.lang.String%29\"><$c$c>String.split(String正则表达式） 被调用时，它被称为与限制 = 0，这将删除阵列中的所有尾随空字符串（在大多数情况下，见下文）。

When String.split(String regex) is called, it is called with limit = 0, which will remove all trailing empty strings in the array (in most cases, see below).

的实际行为 String.split（字符串正则表达式）还是比较混乱的：

The actual behavior of String.split(String regex) is quite confusing:

• 分割一个空字符串将导致长度为1的数组的空字符串拆分将总是导致包含空字符串长度1阵列的


• 拆分，或;;;与正则表达式是，将导致空数组。的非空字符串分割将导致删除阵列中的所有尾随空字符串的

• Splitting an empty string will result in an array of length 1. Empty string split will always result in length 1 array containing the empty string.
• Splitting ";" or ";;;" with regex being ";" will result in an empty array. Non-empty string split will result in all trailing empty strings in the array removed.

以上可以观察到至​​少5的Java到Java 8。行为

The behavior above can be observed from at least Java 5 to Java 8.

有是企图去改变在拆分 JDK-6559590 。然而，它很快就在 JDK-8028321 恢复时，它会导致回归在不同的地方。这种变化从不入初始Java 8版本。

There was an attempt to change the behavior to return an empty array when splitting an empty string in JDK-6559590. However, it was soon reverted in JDK-8028321 when it causes regression in various places. The change never makes it into the initial Java 8 release.

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