Class AnnotationUseStyleCheck

  • All Implemented Interfaces:
    Configurable, Contextualizable

    public final class AnnotationUseStyleCheck
    extends AbstractCheck
    This check controls the style with the usage of annotations.

    Annotations have three element styles starting with the least verbose.

    To not enforce an element style a IGNORE type is provided. The desired style can be set through the elementStyle property.

    Using the EXPANDED style is more verbose. The expanded version is sometimes referred to as "named parameters" in other languages.

    Using the COMPACT style is less verbose. This style can only be used when there is an element called 'value' which is either the sole element or all other elements have default values.

    Using the COMPACT_NO_ARRAY style is less verbose. It is similar to the COMPACT style but single value arrays are flagged. With annotations a single value array does not need to be placed in an array initializer. This style can only be used when there is an element called 'value' which is either the sole element or all other elements have default values.

    The ending parenthesis are optional when using annotations with no elements. To always require ending parenthesis use the ALWAYS type. To never have ending parenthesis use the NEVER type. To not enforce a closing parenthesis preference a IGNORE type is provided. Set this through the closingParens property.

    Annotations also allow you to specify arrays of elements in a standard format. As with normal arrays, a trailing comma is optional. To always require a trailing comma use the ALWAYS type. To never have a trailing comma use the NEVER type. To not enforce a trailing array comma preference a IGNORE type is provided. Set this through the trailingArrayComma property.

    By default the ElementStyle is set to EXPANDED, the TrailingArrayComma is set to NEVER, and the ClosingParens is set to ALWAYS.

    According to the JLS, it is legal to include a trailing comma in arrays used in annotations but Sun's Java 5 & 6 compilers will not compile with this syntax. This may in be a bug in Sun's compilers since eclipse 3.4's built-in compiler does allow this syntax as defined in the JLS. Note: this was tested with compilers included with JDK versions 1.5.0.17 and 1.6.0.11 and the compiler included with eclipse 3.4.1.

    See Java Language specification, §9.7.

    An example shown below is set to enforce an EXPANDED style, with a trailing array comma set to NEVER and always including the closing parenthesis.

     <module name="AnnotationUseStyle">
        <property name="ElementStyle"
            value="EXPANDED"/>
        <property name="TrailingArrayComma"
            value="NEVER"/>
        <property name="ClosingParens"
            value="ALWAYS"/>
     </module>
     
    Author:
    Travis Schneeberger