string.split方法返回數組長度不夠

String s ="1,2,3,,,";
String[] ss = s.split(",");
System.out.println(ss.length);

系統輸出數組長度爲：3

若要數組長度變爲6，以下

String[] sss = s.split(",",-1);
System.out.println(sss.length);