java - Behaviour of String.split() when input is empty

Question

As the title explains the query

Can somebody please explain the behavior of following two outputs.

"".split(",").length

gives output

1

where as

",".split(",").length

gives output

0

Answer 1

在第一种情况下，返回原始字符串，因为没有找到分隔符。

从API 文档：

如果表达式与输入的任何部分都不匹配，则结果数组只有一个元素，即这个字符串。

Answer 2

http://docs.oracle.com/javase/6/docs/api/java/lang/String.html#split(java.lang.String,%20int)

尾随的空字符串被丢弃。

尝试：

"Foo,".split(",").length // should be 1
",foo".split(",").length // should be 1