Class ArrayTrailingCommaCheck

  • All Implemented Interfaces:
    Configurable, Contextualizable

    public class ArrayTrailingCommaCheck
    extends AbstractCheck

    Checks if array initialization contains optional trailing comma.

    Rationale: Putting this comma in make is easier to change the order of the elements or add new elements on the end. Main benefit of a trailing comma is that when you add new entry to an array, no surrounding lines are changed.

    The check demands a comma at the end if neither left nor right curly braces are on the same line as the last element of the array.

     return new int[] { 0 };
     return new int[] { 0
         };
     return new int[] {
         0 };
     
     {
         100000000000000000000,
         200000000000000000000, // OK
     }
    
     {
         100000000000000000000,
         200000000000000000000,
         300000000000000000000,  // Just this line added, no other changes
     }
     

    If closing brace is on the same line as training comma, this benefit is gone (as the Check does not demand a certain location of curly braces the following two cases will not produce a violation):

     {100000000000000000000,
         200000000000000000000,} // Trailing comma not needed, line needs to be modified anyway
    
     {100000000000000000000,
         200000000000000000000, // Modified line
         300000000000000000000,} // Added line
     

    If opening brace is on the same line as training comma there's also (more arguable) problem:

     {100000000000000000000, // Line cannot be just duplicated to slightly modify entry
     }
    
     {100000000000000000000,
         100000000000000000001, // More work needed to duplicate
     }
     

    An example of how to configure the check is:

     <module name="ArrayTrailingComma"/>
     
    Author:
    o_sukhodolsky