Java细节备忘

String[] split = "abc".split(":");
System.out.println(split.length);

split = "abc:".split(":");
System.out.println(split.length);

split = "abc:def".split(":");
System.out.println(split.length);

//结果是 1 1 2

String text = "abcdef,ghi,jk";
System.out.println(text.replace(",","")); System.out.println(text.replaceAll(",",""));

//结果： abcdefghijk abcdefghijk

Object n = null;
String[] a;
a = (String[])n;
System.out.println("a = " + a);

//结果 a = null