Package org.apache.cayenne.access.jdbc

# Class DistinctResultIterator<T>

java.lang.Object
org.apache.cayenne.access.jdbc.DistinctResultIterator<T>

All Implemented Interfaces:
  `AutoCloseable`, `Iterable<T>`, `ResultIterator<T>`

public class DistinctResultIterator<T> extends Object implements ResultIterator<T>
A ResultIterator that does in-memory filtering of rows to return only distinct rows. Distinct comparison is done by comparing ObjectIds created from each row. Internally DistinctResultIterator wraps another ResultIterator that provides the actual rows.

Since:
  3.0

- ## Field Summary

  Fields
  Modifier and Type
  Field
  Description
  `protected boolean`
  `compareFullRows`
  `protected DbEntity`
  `defaultEntity`
  `protected ResultIterator<T>`
  `delegate`
  `protected Set<Object>`
  `fetchedIds`
  `protected T`
  `nextDataRow`

- ## Constructor Summary

  Constructors
  Constructor
  Description
  `DistinctResultIterator(ResultIterator<T> delegate, DbEntity defaultEntity, boolean compareFullRows)`
  Creates new DistinctResultIterator wrapping another ResultIterator.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `List<T>`
  `allRows()`
  Returns all yet unread rows from ResultSet without closing it.
  `void`
  `close()`
  Closes underlying ResultIterator.
  `boolean`
  `hasNextRow()`
  Returns true if there is at least one more record that can be read from the iterator.
  `Iterator<T>`
  `iterator()`
  `T`
  `nextRow()`
  Returns the next result row that is, depending on the query, may be a scalar value, a DataRow, or an Object[] array containing a mix of scalars and DataRows.
  `void`
  `skipRow()`
  Goes past current row.

  ### Methods inherited from class java.lang.Object

  `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

  ### Methods inherited from interface java.lang.Iterable

  `forEach, spliterator`

- ## Field Details

  - ### delegate

    protected ResultIterator<T> delegate

  - ### fetchedIds

    protected Set<Object> fetchedIds

  - ### nextDataRow

    protected T nextDataRow

  - ### defaultEntity

    protected DbEntity defaultEntity

  - ### compareFullRows

    protected boolean compareFullRows

- ## Constructor Details

  - ### DistinctResultIterator

    public DistinctResultIterator(ResultIterator<T> delegate, DbEntity defaultEntity, boolean compareFullRows)
    Creates new DistinctResultIterator wrapping another ResultIterator.
    Parameters:
      `delegate` - actual result iterator, that will be decorated by this DistinctResultIterator
      `defaultEntity` - an entity needed to build ObjectIds for distinct comparison.

- ## Method Details

  - ### iterator

    public Iterator<T> iterator()
    Specified by:
      `iterator` in interface `Iterable<T>`
    Since:
      4.0

  - ### close

    public void close()
    Closes underlying ResultIterator.
    Specified by:
      `close` in interface `AutoCloseable`
    Specified by:
      `close` in interface `ResultIterator<T>`

  - ### allRows

    public List<T> allRows()
    Description copied from interface: `ResultIterator`
    Returns all yet unread rows from ResultSet without closing it.
    Specified by:
      `allRows` in interface `ResultIterator<T>`
    Since:
      3.0

  - ### hasNextRow

    public boolean hasNextRow()
    Description copied from interface: `ResultIterator`
    Returns true if there is at least one more record that can be read from the iterator.
    Specified by:
      `hasNextRow` in interface `ResultIterator<T>`

  - ### nextRow

    public T nextRow()
    Description copied from interface: `ResultIterator`
    Returns the next result row that is, depending on the query, may be a scalar value, a DataRow, or an Object[] array containing a mix of scalars and DataRows.
    Specified by:
      `nextRow` in interface `ResultIterator<T>`

  - ### skipRow

    public void skipRow()
    Description copied from interface: `ResultIterator`
    Goes past current row. If the row is not needed, this may save some time on data conversion.
    Specified by:
      `skipRow` in interface `ResultIterator<T>`
    Since:
      3.0