## org.apache.lucene.facet.enhancements.association
Class AssociationEnhancement

    java.lang.Object
      org.apache.lucene.facet.enhancements.association.AssociationEnhancement

All Implemented Interfaces:
  CategoryEnhancement

    public class AssociationEnhancement

extends Object
implements CategoryEnhancement

A `CategoryEnhancement` for adding associations data to the index (categories with `AssociationProperty`s).

WARNING: This API is experimental and might change in incompatible ways in the next release.

Constructor Summary
`AssociationEnhancement()`

Method Summary
`boolean` `equals(Object o)` Category enhancements must override `Object.equals(Object)`, as it is used in `EnhancementsPayloadIterator.getCategoryData(CategoryEnhancement)`.
`Object` `extractCategoryTokenData(byte[] buffer, int offset, int length)` Get the data of this enhancement from a category token payload.
`boolean` `generatesCategoryList()` Declarative method to indicate whether this enhancement generates separate category list.
`static AssociationProperty` `getAssociationProperty(CategoryAttribute categoryAttribute)`
`String` `getCategoryListTermText()` Returns the text of this enhancement's category list term.
`CategoryListTokenizer` `getCategoryListTokenizer(org.apache.lucene.analysis.TokenStream tokenizer, EnhancementsIndexingParams indexingParams, TaxonomyWriter taxonomyWriter)` Get the `CategoryListTokenizer` which generates the category list for this enhancement.
`byte[]` `getCategoryTokenBytes(CategoryAttribute categoryAttribute)` Get the bytes to be added to the category token payload for this enhancement.
`Class<? extends CategoryProperty>` `getRetainableProperty()` Get a `CategoryProperty` class to be retained when creating `CategoryParentsStream`.
`int` `hashCode()`
`static boolean` `isAssociationProperty(Class<? extends CategoryProperty> clazz)` For a given class which extends a CategoryProperty, answers whether it is an instance of AssociationProperty (AP) or not.

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

Constructor Detail

### AssociationEnhancement

    public AssociationEnhancement()

Method Detail

### isAssociationProperty

    public static boolean isAssociationProperty(Class<? extends CategoryProperty> clazz)

  For a given class which extends a CategoryProperty, answers whether it is an instance of AssociationProperty (AP) or not.
  This method is a cheaper replacement for a call to `instanceof`. It has two HashSets - one for classes which are an extension to AP and one for the classes which are not. Whenever a property class is introduced:
  - if it is known as a property class extending AP (contained in the validHashSet)- returns true
  - if it is known as a property class NOT extending AP - returns false
  - If it was not matched against both sets, it calls 'instanceof' to find out if it extends AP, puts it in the matching Set and returning true or false accordingly
  NOTE: 'instanceof' is only called once per a Class (not instance) of a property. And as there are few properties (currently 4 concrete implementations) the two sets would be rather small

### generatesCategoryList

    public boolean generatesCategoryList()

  Description copied from interface: `CategoryEnhancement`
  Declarative method to indicate whether this enhancement generates separate category list.

  Specified by:
    `generatesCategoryList` in interface `CategoryEnhancement`
  Returns:
    `true` if generates category list, else `false`.

### getCategoryListTermText

    public String getCategoryListTermText()

  Description copied from interface: `CategoryEnhancement`
  Returns the text of this enhancement's category list term.

  Specified by:
    `getCategoryListTermText` in interface `CategoryEnhancement`
  Returns:
    The text of this enhancement's category list term.

### getCategoryListTokenizer

    public CategoryListTokenizer getCategoryListTokenizer(org.apache.lucene.analysis.TokenStream tokenizer,
                                                          EnhancementsIndexingParams indexingParams,
                                                          TaxonomyWriter taxonomyWriter)

  Description copied from interface: `CategoryEnhancement`
  Get the `CategoryListTokenizer` which generates the category list for this enhancement. If `CategoryEnhancement.generatesCategoryList()` returns `false` this method will not be called.

  Specified by:
    `getCategoryListTokenizer` in interface `CategoryEnhancement`
  Parameters:
    `tokenizer` - The input stream containing categories.
    `indexingParams` - The indexing params to use.
    `taxonomyWriter` - The taxonomy to add categories and get their ordinals.
  Returns:
    A `CategoryListTokenizer` generating the category list for this enhancement, with `tokenizer` as it's input.

### getCategoryTokenBytes

    public byte[] getCategoryTokenBytes(CategoryAttribute categoryAttribute)

  Description copied from interface: `CategoryEnhancement`
  Get the bytes to be added to the category token payload for this enhancement.

  NOTE: The returned array is copied, it is recommended to allocate a new one each time.

  The bytes generated by this method are the input of `CategoryEnhancement.extractCategoryTokenData(byte[], int, int)`.

  Specified by:
    `getCategoryTokenBytes` in interface `CategoryEnhancement`
  Parameters:
    `categoryAttribute` - The attribute of the category.
  Returns:
    The bytes to be added to the category token payload for this enhancement.

### getAssociationProperty

    public static AssociationProperty getAssociationProperty(CategoryAttribute categoryAttribute)

### extractCategoryTokenData

    public Object extractCategoryTokenData(byte[] buffer,
                                           int offset,
                                           int length)

  Description copied from interface: `CategoryEnhancement`
  Get the data of this enhancement from a category token payload.

  The input bytes for this method are generated in `CategoryEnhancement.getCategoryTokenBytes(CategoryAttribute)`.

  Specified by:
    `extractCategoryTokenData` in interface `CategoryEnhancement`
  Parameters:
    `buffer` - The payload buffer.
    `offset` - The offset of this enhancement's data in the buffer.
    `length` - The length of this enhancement's data (bytes).
  Returns:
    An Object containing the data.

### getRetainableProperty

    public Class<? extends CategoryProperty> getRetainableProperty()

  Description copied from interface: `CategoryEnhancement`
  Get a `CategoryProperty` class to be retained when creating `CategoryParentsStream`.

  Specified by:
    `getRetainableProperty` in interface `CategoryEnhancement`
  Returns:
    the `CategoryProperty` class to be retained when creating `CategoryParentsStream`, or `null` if there is no such property.

### equals

    public boolean equals(Object o)

  Description copied from interface: `CategoryEnhancement`
  Category enhancements must override `Object.equals(Object)`, as it is used in `EnhancementsPayloadIterator.getCategoryData(CategoryEnhancement)`.

  Specified by:
    `equals` in interface `CategoryEnhancement`
  Overrides:
    `equals` in class `Object`

### hashCode

    public int hashCode()

  Overrides:
    `hashCode` in class `Object`