a problem where OO seems more natural to me, implementing a utility class not instantiable. how to prevent instantiation, thanks to http://stackoverflow.com/questions/10558393/prevent-instantiation-of-an-object-outside-its-factory-method/10558404#105…

1.关闭防火墙:ufw disable 2.以.开头的表示隐藏文件 3..和..分别代表当前目录以及当前目录的父目录 4.显示当前用户所在目录pwd 5.touch创建空文件 6.mkdir创建新目录 7.cp -R [源文件夹] [目标文件夹]复制文件夹-R或–recursive表示递归处理,将指定目录下的所有文件与子目录一并处理. 8.cp [源文件] [目标文件]复制文件 9.mv移动文件,同时可以给文件更名 10.rm删除文件,如果要删除文件夹,需要加上参数-R,参数意义和第7条相同 1…

1:窗体首次加载时最大化 (1):主窗体 this.WindowState = FormWindowState.Maximized; //窗体显示中间部分,不显示窗体名称和最小化.最大化.关闭按钮             this.FormBorderStyle = FormBorderStyle.None; this.WindowState = FormWindowState.Maximized; (2):子窗体 设置父窗体的属性:IsMdiContainer=True Form f = ne…

DZY Loves Chemistry time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output DZY loves chemistry, and he enjoys mixing chemicals. DZY has n chemicals, and m pairs of them will react. He wants to pou…

DZY Loves Chessboard time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output DZY loves chessboard, and he enjoys playing with it. He has a chessboard of n rows and m columns. Some cells of the ches…

time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output Little Susie loves strings. Today she calculates distances between them. As Susie is a small girl after all, her strings contain only digits…

Toy Cars time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output Little Susie, thanks to her older brother, likes to play with cars. Today she decided to set up a tournament between them. The proce…

string str1 = "C#操作字符串<几种常见方式>如下"; string str2 = "C#操作字符串";     //比较字符串 Compare,Equal             //1,compare,int 1             string.Compare(str1, str2);             str1.CompareTo(str2);             //2,equal,bool true        …

一.规划 (一)硬件资源 10.171.29.191 master 10.173.54.84  slave1 10.171.114.223 slave2 (二)基本资料 用户:  jediael 目录:/opt/jediael/ 二.环境配置 (一)统一用户名密码,并为jediael赋予执行所有命令的权限 #passwd # useradd jediael # passwd jediael # vi /etc/sudoers 增加以下一行: jediael ALL=(ALL) ALL (二)创建…

1.Shell$ExitCodeException 现象:运行hadoop job时出现如下异常: 14/07/09 14:42:50 INFO mapreduce.Job: Task Id : attempt_1404886826875_0007_m_000000_1, Status : FAILED Exception from container-launch: org.apache.hadoop.util.Shell$ExitCodeException:  org.apache.hado…