Java中split方法的细节问题。

先看一段代码：

String a="a::::::"; 
String[] str=a.split(":"); 
// 返回长度为1
System.out.println(str.length); 

你会觉得长度应该不是1，那是为什么呢？ 看一下jdk中关于方法的说明。

split

public String[] split(String regex)

Splits this string around matches of the given regular expression.

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.

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

Regex	Result
:	{ "boo", "and", "foo" }
o	{ "b", "", ":and:f" }

发现红色的这句话很关键“结尾的空白字符串会被略去，不会包含在返回的结果数组中。

所以开始的代码返回的长度为1.