Coding Guidelines

General rules

  • All files must have an Apache copyright header at the top of the file.
  • Code should be removed rather than commented out.
  • All public functions should have javadoc comments.
  • Always use braces to surround branches.
  • try-finally should be avoided.


  • All files must have an 100 character maximum line length.
  • Indentation should be 2 spaces.
  • Files should use spaces instead of tabs.
  • Wrapping lines
    • Break after a comma.
    • Break before an operator.
    • Prefer higher-level breaks to lower-level breaks.
    • Align the new line with beginning of the expression at the same level on the previous line.
    • If the above rules lead to confusing code, just indent 8 spaces.
  • One variable declaration per a line.


  • Packages should be all lowercase.
    • C++ code should be in orc::.
    • Java code should be in org.apache.orc, except for compatibility classes, which should be in
  • Classes should be in mixed case.
  • Variables should be in camel case.
  • Constants should be in upper case.

Static code analysis tool

You can download this plugin to load java/checkstyle.xml to check the java code style. This way you get checkstyle errors/warnings already when you are coding.