DistinctDataBag (Apache Jena ARQ)

java.lang.Object
- org.apache.jena.atlas.data.AbstractDataBag<E>
- - org.apache.jena.atlas.data.SortedDataBag<E>
  - - org.apache.jena.atlas.data.DistinctDataBag<E>

All Implemented Interfaces:

java.lang.Iterable<E>, DataBag<E>, org.apache.jena.atlas.lib.Closeable, org.apache.jena.atlas.lib.Sink<E>

Direct Known Subclasses:

DistinctDataNet
```
public class DistinctDataBag<E>
extends SortedDataBag<E>
```
This data bag will gather distinct items in memory until a size threshold is passed, at which point it will write out all of the items to disk using the supplied serializer.

After adding is finished, call iterator() to set up the data bag for reading back items and iterating over them. The iterator will retrieve only distinct items.

IMPORTANT: You may not add any more items after this call. You may subsequently call iterator() multiple times which will give you a new iterator for each invocation. If you do not consume the entire iterator, you should call Iter.close(Iterator) to close any FileInputStreams associated with the iterator.

Additionally, make sure to call SortedDataBag.close() when you are finished to free any system resources (preferably in a finally block).

Implementation Notes: Data is stored without duplicates as it comes in in a HashSet. When it is time to spill, that data is sorted and written to disk. An iterator that eliminates adjacent duplicates is used in conjunction with the SortedDataBag's iterator.

Constructor Summary

Constructors
Constructor	Description
`DistinctDataBag(ThresholdPolicy<E> policy, SerializationFactory<E> serializerFactory, java.util.Comparator<E> comparator)`

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`boolean`	`isDistinct()`	Find out if the bag is distinct.
`boolean`	`isSorted()`	Find out if the bag is sorted.
`java.util.Iterator<E>`	`iterator()`	Returns an iterator over a set of elements of type E.

Methods inherited from class org.apache.jena.atlas.data.SortedDataBag
add, cancel, close, flush, isCancelled, isClosed

Methods inherited from class org.apache.jena.atlas.data.AbstractDataBag
isEmpty, send, size

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

Methods inherited from interface org.apache.jena.atlas.data.DataBag
addAll, addAll

Methods inherited from interface java.lang.Iterable
forEach, spliterator

- Constructor Detail
  - DistinctDataBag
```
public DistinctDataBag(ThresholdPolicy<E> policy,
                       SerializationFactory<E> serializerFactory,
                       java.util.Comparator<E> comparator)
```
- Method Detail
  - isSorted
```
public boolean isSorted()
```
    Description copied from interface: DataBag
    
    Find out if the bag is sorted.
    
    Specified by:
    
    isSorted in interface DataBag<E>
    
    Overrides:
    
    isSorted in class SortedDataBag<E>
    
    Returns:
    
    true if this is a sorted data bag, false otherwise.
  - isDistinct
```
public boolean isDistinct()
```
    Description copied from interface: DataBag
    
    Find out if the bag is distinct.
    
    Specified by:
    
    isDistinct in interface DataBag<E>
    
    Overrides:
    
    isDistinct in class SortedDataBag<E>
    
    Returns:
    
    true if the bag is a distinct bag, false otherwise.
  - iterator
```
public java.util.Iterator<E> iterator()
```
    Description copied from class: SortedDataBag
    
    Returns an iterator over a set of elements of type E. If you do not exhaust the iterator, you should call Iter.close(Iterator) to be sure any open file handles are closed.
    
    Specified by:
    
    iterator in interface java.lang.Iterable<E>
    
    Overrides:
    
    iterator in class SortedDataBag<E>
    
    Returns:
    
    an Iterator