摘要： 1.声明一个map: Map map = new HashMap(); 2.向map中放值,注意：map是key-value的形式存放的.如: map.put("sa","dd"); 3.从map中取值:String str = map.get("sa").toString();结果是:str = "dd"; 4.遍历一个map，从中取得key 和value JDK1.5 Map m... 阅读全文

摘要： jdk中原本是个filo队列，现在我改了一下源码，成为一个fifo的。 import java.util.*; public class Stack extends Vector { public Stack() { } public Object ... 阅读全文

摘要： select * from (select 姓名,sum(工资) as 工资数,sum(奖金) as 奖金数 from 员工表 Group by 姓名) as t order by 工资数 or: select 姓名,sum(工资) as 工资数,sum(奖金) as 奖金数 from 员工表 Group by 姓名 order by 工资数 or: select 姓名,sum(工资) as 工资... 阅读全文