不知道字符串分割是如何工作的

I don't get the following:

我不明白以下几点:

In the following String:

在以下字符串:

String s = "1234;x;;y;";

字符串s =“1234;x、y”;

if I do:
String[] s2 = s.split(";");

如果是:String[] s2 = s.s split(";");

I get s2.length to be 4 and

我得到s2。长度为4。

s2[0] = "1234";  
s2[1] = "x";  
s2[2] = "";  
s2[3] = "y"; 

But in the string: String s = "1234;x;y;;";

但在字符串中:string s = "1234;x;y; ";

I get:

我得到:

s2.length to be 3 and

s2。长度为3。

s2[0] = "1234";  
s2[1] = "x";  
s2[2] = "y"; 

?

吗?

What is the difference and I don't get 4 in the latter case as well?

后一种情况下，我没有得到4，有什么区别?

UPDATE:
Using -1 is not was I was expecting as behavior.
I mean the last semicolon is the end of the String so in the latter example I was also expecting 4 as length of the array

更新:使用-1不是我期望的行为。我的意思是最后一个分号是字符串的末尾，所以在后面的例子中，我也期望数组的长度是4

6 个解决方案

#1

From the docs,

的文档,

This method works as if by invoking the two-argument split method with the given expression and a limit argument of zero. Trailing empty strings are therefore not included in the resulting array.

该方法通过调用具有给定表达式和限制参数为0的双参数分割方法来工作。因此，结果数组中不包含尾空字符串。

UPDATE:

更新:

You have five substrings separated by ; In the second case, these are 1234, x, y, and . As per the docs, all empty substrings (at the end) which result from the split operation would be eliminated. For details, look here.

有5个子字符串;在第二种情况下，这些是1234 x y和。根据文档，所有由分割操作产生的空子字符串(最后)都将被删除。详情,请看这里。

If n is zero then the pattern will be applied as many times as possible, the array can have any length, and trailing empty strings will be discarded.

如果n为0，那么模式将被尽可能多地应用，数组可以有任意长度，拖尾空字符串将被丢弃。

The string boo:and:foo, for example, yields the following results with these parameters:

例如，字符串boo:and:foo通过这些参数产生如下结果:

Regex   Limit   Result
  :       2     { "boo", "and:foo" }
  :       5     { "boo", "and", "foo" }
  :      -2     { "boo", "and", "foo" }
  o       5     { "b", "", ":and:f", "", "" }
  o      -2     { "b", "", ":and:f", "", "" }
  o       0     { "b", "", ":and:f" }   // all the empty substrings at the end were eliminated

#2

Trailing empty strings are omitted. If you need them use the approach described in http://www.xinotes.org/notes/note/226/

尾空字符串被省略。如果需要，请使用http://www.xinotes.org/notes/note/226/中描述的方法

#3

From http://docs.oracle.com/javase/6/docs/api/java/lang/String.html#split(java.lang.String)

从http://docs.oracle.com/javase/6/docs/api/java/lang/String.html分裂(以)

This method works as if by invoking the two-argument split method with the given expression and a limit argument of zero. Trailing empty strings are therefore not included in the resulting array.

该方法通过调用具有给定表达式和限制参数为0的双参数分割方法来工作。因此，结果数组中不包含尾空字符串。

#4

Good question. If you check the API documentation for String.split() and check the example with "boo:foo" then you can see that the trailing empty strings are omitted.

好问题。如果您检查String.split()的API文档并使用“boo:foo”检查示例，那么您可以看到末尾的空字符串被省略了。

This method works as if by invoking the two-argument split method with the given expression and a limit argument of zero. Trailing empty strings are therefore not included in the resulting array.

该方法通过调用具有给定表达式和限制参数为0的双参数分割方法来工作。因此，结果数组中不包含尾空字符串。

The string "boo:and:foo", for example, yields the following results with these expressions:

例如，字符串“boo:and:foo”将使用以下表达式生成以下结果:

Regex Result

正则表达式的结果

: { "boo", "and", "foo" }

: {"boo"和"foo"}

o { "b", "", ":and:f" }

o {"b"， ""， ":和:f"}

#5

Thats default behavior of split method in java to not return empty tokens . ]

这是java中split方法不返回空令牌的默认行为。]

s.split("\;", -1); should return empty token

s.split(“\;",1);应该返回空令牌

#6

Why not check what does the documention says first. Here is the link:

为什么不先检查一下文件上写的是什么?这是链接:

http://docs.oracle.com/javase/6/docs/api/java/lang/String.html#split%28java.lang.String%29

http://docs.oracle.com/javase/6/docs/api/java/lang/String.html分裂% 28以% 29

And here is your answer:

这是你的答案:

Trailing empty strings are therefore not included in the resulting array.

因此，结果数组中不包含尾空字符串。