摘要：
字符串的常用性应该属于top3 // strings/Concatenation.java public class Concatenation { public static void main(String[] args) { String mango = "mango"; String s = 阅读全文
摘要：
举个例子 // validating/CountedList.java // Keeps track of how many of itself are created. package validating; import java.util.*; public class CountedList 阅读全文