空字符串和单个分隔符字符串上的字符串拆分行为

Question

这是这个问题的后续行动.

问题在于下面的第二行.

"".split("x");   //returns {""}   // ok
"x".split("x");  //returns {}   but shouldn't it return {""} because it's the string before "x" ?
"xa".split("x"); //returns {"", "a"}    // see?, here "" is the first string returned
"ax".split("x"); //returns {"a"}

Answer 1

不,因为根据相关的javadoc "尾随空字符串将被丢弃".

Answer 2

具体根据java.util.regex.Pattern 源,其String.split(..)使用,

"".split("x");   // returns {""} - valid - when no match is found, return the original string
"x".split("x");  // returns {} - valid - trailing empty strings are removed from the resultant array {"", ""}
"xa".split("x"); // returns {"", "a"} - valid - only trailing empty strings are removed
"ax".split("x"); // returns {"a"} - valid - trailing empty strings are removed from the resultant array {"a", ""}