给变量和函数起个不啰嗦的名字
写代码就像写作文，所以Joshua Bloch在Coder at Work的采访中推荐了一本写作书，The Elements of Style，和 一本词典，Merriam-Webster’s Collegiate Dictionary, 11th Edition。
强烈推荐“Long Names Are Long”这篇文章，可以帮助我们给函数或者变量命名时更加简洁。 下面是文章中给出的一些例子（例子的上下文见文章），
// Bad:
String nameString;
DockableModelessWindow dockableModelessWindow;
// Better:
String name;
DockableModelessWindow window;
// Bad:
List<DateTime> holidayDateList;
Map<Employee, Role> employeeRoleHashMap;
// Better:
List<DateTime> holidays;
Map<Employee, Role> employeeRoles;
// Bad:
mergeTableCells(List<TableCell> cells)
sortEventsUsingComparator(List<Event> events,
Comparator<Event> comparator)
// Better:
merge(List<TableCell> cells)
sort(List<Event> events, Comparator<Event> comparator)
Hash Join
Hash join是数据库实现join操作的一种算法。
- First prepare a hash table of the smaller relation. The hash table entries consist of the join attribute and its row.
- Once the hash table is built, scan the larger relation and find the relevant rows from the smaller relation by looking in the hash table.
有3种基本的join实现算法：
Three fundamental algorithms for performing a join operation exist: nested loop join, sort-merge join and hash join.
Nested loop join就是两个简单粗暴的for loop。
Javascript Engine in Java
A colleague recently asked me to extract some information/text from a json file in a Docker container. This Docker container has no things like Python or Perl included, and it’s dedicated to Java application only. Parsing json with grep/awk seems a bit intimidating. At last, I recalled that Java is shipped with a Javascript engine and after simply googling found the jjs. We used Javascript as the script language and jjs as the script interpreter to solve the problem.
Java SE 8 will instead ship with a new engine called Oracle Nashorn, which is based on JSR 292 and invokedynamic. It provides better compliance with the ECMA normalized JavaScript specification …
To do so, builds of Oracle’s JDK or OpenJDK include a command-line tool called jjs. It can be found in the bin/ folder of a JDK installation along with the well-known java, javac, or jar tools.
More details in this doc
Increase Number in Vim
How do you increase a number directly under the cursor?
光标放在数字上，按Ctrl+A原数值加1；按Ctrl+X减1。
10Ctrl+A，在原数值上加10.
