Package org.eclipse.rdf4j.query.algebra.evaluation.iterator

## Class LeftJoinIterator

- java.lang.Object
- - org.eclipse.rdf4j.common.iteration.AbstractCloseableIteration<E,​X>
  - - org.eclipse.rdf4j.common.iteration.LookAheadIteration<BindingSet,​QueryEvaluationException>
    - - org.eclipse.rdf4j.query.algebra.evaluation.iterator.LeftJoinIterator

- All Implemented Interfaces:
    `AutoCloseable`, `CloseableIteration<BindingSet,​QueryEvaluationException>`, `Iteration<BindingSet,​QueryEvaluationException>`
  Direct Known Subclasses:
    `BadlyDesignedLeftJoinIterator`

      public class LeftJoinIterator
      extends LookAheadIteration<BindingSet,​QueryEvaluationException>

- - ### Constructor Summary

    Constructors
    Constructor | Description
    --- | ---
    `LeftJoinIterator​(EvaluationStrategy strategy, LeftJoin join, BindingSet bindings, QueryEvaluationContext context)` |
    `LeftJoinIterator​(QueryEvaluationStep left, QueryEvaluationStep right, QueryValueEvaluationStep joinCondition, BindingSet bindings, Set<String> scopeBindingNamse)` |

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method | Description
    --- | --- | ---
    `protected BindingSet` | `getNextElement()` | Gets the next element.
    `protected void` | `handleClose()` | Called by `AbstractCloseableIteration.close()` when it is called for the first time.

    - ### Methods inherited from class org.eclipse.rdf4j.common.iteration.LookAheadIteration

      `hasNext, next, remove`

    - ### Methods inherited from class org.eclipse.rdf4j.common.iteration.AbstractCloseableIteration

      `close, isClosed`

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

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

    - ### Methods inherited from interface org.eclipse.rdf4j.common.iteration.Iteration

      `stream`

- - ### Constructor Detail

    - #### LeftJoinIterator

          public LeftJoinIterator​(EvaluationStrategy strategy,
                                  LeftJoin join,
                                  BindingSet bindings,
                                  QueryEvaluationContext context)
                           throws QueryEvaluationException

      Throws:
        `QueryEvaluationException`

    - #### LeftJoinIterator

          public LeftJoinIterator​(QueryEvaluationStep left,
                                  QueryEvaluationStep right,
                                  QueryValueEvaluationStep joinCondition,
                                  BindingSet bindings,
                                  Set<String> scopeBindingNamse)
                           throws QueryEvaluationException

      Throws:
        `QueryEvaluationException`

  - ### Method Detail

    - #### getNextElement

          protected BindingSet getNextElement()
                                       throws QueryEvaluationException

      Description copied from class: `LookAheadIteration`
      Gets the next element. Subclasses should implement this method so that it returns the next element.
      Specified by:
        `getNextElement` in class `LookAheadIteration<BindingSet,​QueryEvaluationException>`
      Returns:
        The next element, or null if no more elements are available.
      Throws:
        `QueryEvaluationException`

    - #### handleClose

          protected void handleClose()
                              throws QueryEvaluationException

      Description copied from class: `AbstractCloseableIteration`
      Called by `AbstractCloseableIteration.close()` when it is called for the first time. This method is only called once on each iteration. By default, this method does nothing.
      Overrides:
        `handleClose` in class `LookAheadIteration<BindingSet,​QueryEvaluationException>`
      Throws:
        `QueryEvaluationException`