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## com.puppycrawl.tools.checkstyle.checks.annotation
Class AnnotationUseStyleCheck

    java.lang.Object
      com.puppycrawl.tools.checkstyle.api.AutomaticBean
          com.puppycrawl.tools.checkstyle.api.AbstractViolationReporter
              com.puppycrawl.tools.checkstyle.api.Check
                  com.puppycrawl.tools.checkstyle.checks.annotation.AnnotationUseStyleCheck

All Implemented Interfaces:
  Configurable, Contextualizable

    public final class AnnotationUseStyleCheck

extends Check

This check controls the style with the usage of annotations.

Annotations have three element styles starting with the least verbose.

- `COMPACT_NO_ARRAY`
- `COMPACT`
- `EXPANDED`

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 valuess.

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 ClosingParans 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, sections 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

Nested Class Summary
`static class` | `AnnotationUseStyleCheck.ClosingParens` Defines the two styles for defining elements in an annotation.
`static class` | `AnnotationUseStyleCheck.ElementStyle` Defines the styles for defining elements in an annotation.
`static class` | `AnnotationUseStyleCheck.TrailingArrayComma` Defines the two styles for defining elements in an annotation.

Constructor Summary
`AnnotationUseStyleCheck()`

Method Summary
`int[]` | `getAcceptableTokens()` The configurable token set.
`int[]` | `getDefaultTokens()` Returns the default token a check is interested in.
`int[]` | `getRequiredTokens()` The tokens that this check must be registered for.
`void` | `setClosingParens(String aParens)` Sets the ClosingParens from a string.
`void` | `setElementStyle(String aStyle)` Sets the ElementStyle from a string.
`void` | `setTrailingArrayComma(String aComma)` Sets the TrailingArrayComma from a string.
`void` | `visitToken(DetailAST aAST)` Called to process a token.

Methods inherited from class com.puppycrawl.tools.checkstyle.api.Check
`beginTree, destroy, finishTree, getClassLoader, getFileContents, getLines, getTabWidth, getTokenNames, init, leaveToken, log, log, setClassLoader, setFileContents, setMessages, setTabWidth, setTokens`

Methods inherited from class com.puppycrawl.tools.checkstyle.api.AbstractViolationReporter
`getCustomMessages, getId, getMessageBundle, getSeverity, getSeverityLevel, log, setId, setSeverity`

Methods inherited from class com.puppycrawl.tools.checkstyle.api.AutomaticBean
`configure, contextualize, finishLocalSetup, getConfiguration, setupChild`

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Constructor Detail

### AnnotationUseStyleCheck

    public AnnotationUseStyleCheck()

Method Detail

### setElementStyle

    public void setElementStyle(String aStyle)

  Sets the ElementStyle from a string.

  Parameters:
    `aStyle` - string representation
  Throws:
    `org.apache.commons.beanutils.ConversionException` - if cannot convert string.

### setTrailingArrayComma

    public void setTrailingArrayComma(String aComma)

  Sets the TrailingArrayComma from a string.

  Parameters:
    `aComma` - string representation
  Throws:
    `org.apache.commons.beanutils.ConversionException` - if cannot convert string.

### setClosingParens

    public void setClosingParens(String aParens)

  Sets the ClosingParens from a string.

  Parameters:
    `aParens` - string representation
  Throws:
    `org.apache.commons.beanutils.ConversionException` - if cannot convert string.

### getDefaultTokens

    public int[] getDefaultTokens()

  Returns the default token a check is interested in. Only used if the configuration for a check does not define the tokens.

  Specified by:
    `getDefaultTokens` in class `Check`
  Returns:
    the default tokens
  See Also:
    `TokenTypes`

### getRequiredTokens

    public int[] getRequiredTokens()

  The tokens that this check must be registered for.

  Overrides:
    `getRequiredTokens` in class `Check`
  Returns:
    the token set this must be registered for.
  See Also:
    `TokenTypes`

### getAcceptableTokens

    public int[] getAcceptableTokens()

  The configurable token set. Used to protect Checks against malicious users who specify an unacceptable token set in the configuration file. The default implementation returns the check's default tokens.

  Overrides:
    `getAcceptableTokens` in class `Check`
  Returns:
    the token set this check is designed for.
  See Also:
    `TokenTypes`

### visitToken

    public void visitToken(DetailAST aAST)

  Called to process a token.

  Overrides:
    `visitToken` in class `Check`
  Parameters:
    `aAST` - the token to process

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