String.split():
------------------------------------------- String test = "123,123,,123,,"; ------------------------------------------- //结尾的空格元素，不会作为arr的一个元素而返回 split(",");
String[] arr1 = test.split(","); System.out.println(arr1.length); ==>4
------------------------------------------- //结尾的空格将不会作为arr的一个元素 split(",",0);//trailing empty strings will be discarded
String[] arr2 = test.split(",", 0); System.out.println(arr2.length); ==>4
------------------------------------------- //当第二个参数<0时，表示不论是否是空格，都算一个结果 split(",",-1);
String[] arr3 = test.split(",",-1); System.out.println(arr3.length); ==>6
------------------------------------------- //第二个参数>0,表示需要拆分出的数组个数 为这个参数 split(",",2); String[] arr4 = test.split(",",2); System.out.println(arr3.length); ==>2 {"123" , "123,,123,,"}