java.lang.Object
- com.googlecode.cqengine.resultset.ResultSet<O>

All Implemented Interfaces:

Closeable, AutoCloseable, Iterable<O>

Direct Known Subclasses:

CloseableResultSet, DeduplicatingResultSet, FilteringResultSet, ObjectStoreResultSet, ResultSetDifference, ResultSetIntersection, ResultSetUnion, ResultSetUnionAll, StoredResultSet, WrappedResultSet
```
public abstract class ResultSet<O>
extends Object
implements Iterable<O>, Closeable
```
Author:

Niall Gallagher

Constructor Summary

Constructors
Constructor Description

ResultSet()

Method Summary

All Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method	Description
`abstract void`	`close()`	Releases any resources or closes the transaction which was opened for this ResultSet.
`abstract boolean`	`contains(O object)`	Returns true if this `ResultSet` contains the given object, false if it does not.
`abstract int`	`getMergeCost()`	Returns an estimate of the cost of merging (or otherwise processing) objects matching the query.
`abstract Query<O>`	`getQuery()`	Returns the query for which this ResultSet provides results.
`abstract QueryOptions`	`getQueryOptions()`	Returns the query options associated with the query.
`abstract int`	`getRetrievalCost()`	Returns an estimate of the cost of looking up objects matching the query underlying this `ResultSet` in the index.
`boolean`	`isEmpty()`	Checks if this `ResultSet` if iterated would not return any objects (i.e.
`boolean`	`isNotEmpty()`	Checks if this `ResultSet` if iterated would return some objects (i.e.
`abstract Iterator<O>`	`iterator()`	Returns an `Iterator` over objects matching the query for which this `ResultSet` was constructed.
`abstract boolean`	`matches(O object)`	Similar to the `contains(Object)` method, but checks for logical containment in the ResultSet as opposed to physical containment in the ResultSet.
`abstract int`	`size()`	Returns the number of objects which would be returned by this `ResultSet` if iterated.
`Spliterator<O>`	`spliterator()`	Creates a `Spliterator` over objects matching the query for which this `ResultSet` was constructed.
`Stream<O>`	`stream()`	Returns a `Stream` of objects matching the query for which this `ResultSet` was constructed.
`O`	`uniqueResult()`	Returns the first object returned by the iterator of this `ResultSet`, and throws an exception if the iterator does not provide exactly one object.

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

- Constructor Detail
  - ResultSet
```
public ResultSet()
```
- Method Detail
  - iterator
```
public abstract Iterator<O> iterator()
```
    Returns an Iterator over objects matching the query for which this ResultSet was constructed.
    
    Specified by:
    
    iterator in interface Iterable<O>
    
    Returns:
    
    An Iterator over objects matching the query for which this ResultSet was constructed
  - contains
```
public abstract boolean contains(O object)
```
    Returns true if this ResultSet contains the given object, false if it does not.
    Note that the cost of calling this method will most likely be cheaper than iterating all results to check if an object is contained. If indexes are available to support the query, this method will query indexes to check if the object is contained, instead of actually retrieving any data.
    See also the matches(Object) method, which provides a similar function but often with better performance than this method.
    
    Parameters:
    
    object - The object to check for containment in this ResultSet
    
    Returns:
    
    True if this ResultSet contains the given object, false if it does not
  - matches
```
public abstract boolean matches(O object)
```
    Similar to the contains(Object) method, but checks for logical containment in the ResultSet as opposed to physical containment in the ResultSet. Determines if the given object would be contained in the ResultSet, by testing if the given object matches the query for which this ResultSet was generated, instead of actually checking if the object is contained in appropriate indexes.
    This method will typically make the determination by evaluating the query on the given object on-the-fly without accessing indexes, however in some cases this method might delegate to the contains(Object) method to make the determination.
    This method will perform better than contains(Object) in cases where querying indexes is more expensive than querying attributes, which is usually the case.
    
    Parameters:
    
    object - The object to check for logical containment in this ResultSet
    
    Returns:
    
    True if this ResultSet logically contains the given object, false if it does not
  - getQuery
```
public abstract Query<O> getQuery()
```
    Returns the query for which this ResultSet provides results.
    
    Returns:
    
    The query for which this ResultSet provides results.
  - getQueryOptions
```
public abstract QueryOptions getQueryOptions()
```
    Returns the query options associated with the query.
    
    Returns:
    
    The query options associated with the query.
  - uniqueResult
```
public O uniqueResult()
```
    Returns the first object returned by the iterator of this ResultSet, and throws an exception if the iterator does not provide exactly one object.
    
    Returns:
    
    The first object returned by the iterator of this ResultSet
    
    Throws:
    
    NoSuchObjectException - If the iterator indicates no object is available
    
    NonUniqueObjectException - If the iterator indicates more than one object is available
  - getRetrievalCost
```
public abstract int getRetrievalCost()
```
    Returns an estimate of the cost of looking up objects matching the query underlying this ResultSet in the index.
    The query engine will use this to select the index with the lowest cost, when more than one index supporting the query exists for the same attribute.
    An example: a single-level hash index will typically have a lower retrieval cost than a tree-based index. Of course a hash index only supports equality-based retrieval whereas a sorted tree-based index might support equality/less than/greater than or range based retrieval. But for an equality-based query, supported by both indexes, retrieval cost allows the query engine to prefer the hash index.
    
    Returns:
    
    An estimate of the cost of looking up a particular query in the index
  - getMergeCost
```
public abstract int getMergeCost()
```
    Returns an estimate of the cost of merging (or otherwise processing) objects matching the query.
    This will typically be based on the number of objects matching the query.
    
    If the query specifies a simple retrieval from an index, this might be the number of objects matching the query
    
    If the query specifies a union between multiple other sub-queries, this might be the sum of their merge costs
    
    If the query specifies an intersection, this might be the based on the merge cost of the sub-query with the lowest merge cost
    
    The query engine will use this to optimize the order of intersections and unions, and to decide between merging versus filtering strategies.
    Returns:
    
    An estimate of the cost of merging (or otherwise processing) objects matching a query
  - size
```
public abstract int size()
```
    Returns the number of objects which would be returned by this ResultSet if iterated.
    Note that the cost of calling this method depends on the query for which it was constructed.
    For simple queries where a single query is supplied and a matching index exists, or where several such simple queries are supplied and are connected using a simple Or query, calculating the size via this method will be cheaper than iterating through the ResultSet and counting the number of objects individually.
    For more complex queries, where intersections must be performed or where no suitable indexes exist, calling this method can be non-trivial, but it will always be at least as cheap as iterating through the ResultSet and counting the number of objects individually.
    
    Returns:
    
    The number of objects which would be returned by this ResultSet if iterated
  - isEmpty
```
public boolean isEmpty()
```
    Checks if this ResultSet if iterated would not return any objects (i.e. the query does not match any objects).
    This method can be more efficient than calling #size() to check simply if no objects would be returned.
    
    Returns:
    
    True if this ResultSet if iterated would not return any objects; false if the ResultSet would return objects
  - isNotEmpty
```
public boolean isNotEmpty()
```
    Checks if this ResultSet if iterated would return some objects (i.e. the query matches some objects).
    This method can be more efficient than calling #size() to check simply if some objects would be returned.
    
    Returns:
    
    True if this ResultSet if iterated would return some objects; false if the ResultSet would not return any objects
  - close
```
public abstract void close()
```
    Releases any resources or closes the transaction which was opened for this ResultSet.
    Whether or not it is necessary to close the ResultSet depends on which implementation of IndexedCollection is in use and the types of indexes added to it.
    
    Specified by:
    
    close in interface AutoCloseable
    
    Specified by:
    
    close in interface Closeable
  - spliterator
```
public Spliterator<O> spliterator()
```
    Creates a Spliterator over objects matching the query for which this ResultSet was constructed.
    
    Specified by:
    
    spliterator in interface Iterable<O>
    
    Returns:
    
    a Spliterator over objects matching the query for which this ResultSet was constructed
  - stream
```
public Stream<O> stream()
```
    Returns a Stream of objects matching the query for which this ResultSet was constructed.
    The stream is configured such that if BaseStream.close() is called, close() will also be called automatically to close the ResultSet.
    
    Returns:
    
    a Stream of objects matching the query for which this ResultSet was constructed

Class ResultSet<O>

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Methods inherited from interface java.lang.Iterable

Constructor Detail

ResultSet

Method Detail

iterator

contains

matches

getQuery

getQueryOptions

uniqueResult

getRetrievalCost

getMergeCost

size

isEmpty

isNotEmpty

close

spliterator

stream