The code formatting standard in this project is based on the Oracle/Sun Code Convention and Google Java Style.


The coding style is consistent with most of the open source projects with the following callout:

  1. Naming Conventions

    • Variables are camel case beginning with a lowercase letter, e.g. fooBar
    • Constant variables are declared as static final and should be all uppercase ASCII letters delimited by underscore ("_"), e.g. FOO_BAR
  2. Import statement

    • Do not use 'star' imports, e.g. import java.io.*;
    • Import order: java, org, com, gobblin.
  3. Indentation

    • Two spaces should be used as the unit of indentation;
    • Tabs must expand to spaces and the tab width should be set to two;
    • Line length: lines should not exceed 120 characters;
  4. White space

    • Blank lines should be provided to improve readability:
      • Between the local variables in a method and its first statement
      • Between methods
    • Blank spaces should be used in the following circumstances:
      • A keyword followed by a parenthesis should be separated by a space (e.g. while (true) {)
      • A binary operators except . should be separated from their operands by spaces (e.g. a + b);

    • Implementation comments: Block comments (/* ... */), end-of-line comments (//...) can be used to illustrate a particular implementation;
    • Documentation comments (/** ... */) should be used to describe Java classes, interfaces, methods;
  6. Compound statements are lists of statements enclosed in curly braces and should be formatted according to the following conventions:

    • The enclosed statements should be indented one more level than the enclosing statement
    • The opening brace should be on the same line as the enclosing statement (e.g. the 'if' clause)
    • The closing brace should be on a line by itself indented to match the enclosing statement
    • Braces are used around all statements, even single statements, when they are part of a control structure, such as if-else or for statements. This makes it easier to add statements without accidentally introducing bugs due to forgetting to add braces.

Code Style Template File

  • Eclipse
    • Download the codetyle-eclipse.xml, Import the file through Preferences > Java > Code Style > Formatter
    • Download the prefs-eclipse.epf, Import the file File > Import > General > Preferences
  • IntelliJ
    • Download the codestyle-intellij-gobblin.xml, Copy the file to the appropriate codestyles directory for your installation. This is typically ~/.INTELLIJ_VERSION/config/codestyles on Linux (or $HOME/Library/Preferences/INTELLIJ_VERSION/codestyles on Mac). The specific INTELLIJ_VERSION identifier will depend on your version; examples are IntelliJIdeal3, IdeaC15 etc.
    • Restart the IDE
    • Go to File > Settings > Code Style > General > Scheme to select the new style (LinkedIn Gobblin Style)