## org.apache.lucene.search
Class DuplicateFilter

    java.lang.Object
      org.apache.lucene.search.Filter
          org.apache.lucene.search.DuplicateFilter

All Implemented Interfaces:
  Serializable

    public class DuplicateFilter

extends Filter

See Also:
  Serialized Form

Field Summary
`static int` `KM_USE_FIRST_OCCURRENCE`
`static int` `KM_USE_LAST_OCCURRENCE`
`static int` `PM_FAST_INVALIDATION`
`static int` `PM_FULL_VALIDATION`

Constructor Summary
`DuplicateFilter(String fieldName)`
`DuplicateFilter(String fieldName, int keepMode, int processingMode)`

Method Summary
`boolean` `equals(Object obj)`
`DocIdSet` `getDocIdSet(IndexReader reader)` Creates a `DocIdSet` enumerating the documents that should be permitted in search results.
`String` `getFieldName()`
`int` `getKeepMode()`
`int` `getProcessingMode()`
`int` `hashCode()`
`void` `setFieldName(String fieldName)`
`void` `setKeepMode(int keepMode)`
`void` `setProcessingMode(int processingMode)`

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

Field Detail

### KM_USE_FIRST_OCCURRENCE

    public static final int KM_USE_FIRST_OCCURRENCE

See Also:
  Constant Field Values

### KM_USE_LAST_OCCURRENCE

    public static final int KM_USE_LAST_OCCURRENCE

See Also:
  Constant Field Values

### PM_FULL_VALIDATION

    public static final int PM_FULL_VALIDATION

See Also:
  Constant Field Values

### PM_FAST_INVALIDATION

    public static final int PM_FAST_INVALIDATION

See Also:
  Constant Field Values

Constructor Detail

### DuplicateFilter

    public DuplicateFilter(String fieldName)

### DuplicateFilter

    public DuplicateFilter(String fieldName,
                           int keepMode,
                           int processingMode)

Method Detail

### getDocIdSet

    public DocIdSet getDocIdSet(IndexReader reader)
                         throws IOException

  Description copied from class: `Filter`
  Creates a `DocIdSet` enumerating the documents that should be permitted in search results. NOTE: null can be returned if no documents are accepted by this Filter.

  Note: This method will be called once per segment in the index during searching. The returned `DocIdSet` must refer to document IDs for that segment, not for the top-level reader.

  Specified by:
    `getDocIdSet` in class `Filter`
  Parameters:
    `reader` - a `IndexReader` instance opened on the index currently searched on. Note, it is likely that the provided reader does not represent the whole underlying index i.e. if the index has more than one segment the given reader only represents a single segment.
  Returns:
    a DocIdSet that provides the documents which should be permitted or prohibited in search results. NOTE: null can be returned if no documents will be accepted by this Filter.
  Throws:
    `IOException`
  See Also:
    `DocIdBitSet`

### getFieldName

    public String getFieldName()

### setFieldName

    public void setFieldName(String fieldName)

### getKeepMode

    public int getKeepMode()

### setKeepMode

    public void setKeepMode(int keepMode)

### equals

    public boolean equals(Object obj)

  Overrides:
    `equals` in class `Object`

### hashCode

    public int hashCode()

  Overrides:
    `hashCode` in class `Object`

### getProcessingMode

    public int getProcessingMode()

### setProcessingMode

    public void setProcessingMode(int processingMode)

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