org.apache.flink.runtime.util

Class ReusingKeyGroupedIterator<E>

java.lang.Object

org.apache.flink.runtime.util.ReusingKeyGroupedIterator<E>

All Implemented Interfaces:

KeyGroupedIterator<E>

public final class ReusingKeyGroupedIterator<E>
extends Object
implements KeyGroupedIterator<E>

The KeyValueIterator returns a key and all values that belong to the key (share the same key).

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
class	ReusingKeyGroupedIterator.ValuesIterator

Constructor Summary

Constructors

Constructor and Description
ReusingKeyGroupedIterator(MutableObjectIterator<E> iterator, TypeSerializer<E> serializer, TypeComparator<E> comparator) Initializes the KeyGroupedIterator.

Method Summary

Modifier and Type	Method and Description
TypeComparator<E>	getComparatorWithCurrentReference()
E	getCurrent()
ReusingKeyGroupedIterator.ValuesIterator	getValues() Returns an iterator over all values that belong to the current key.
boolean	nextKey() Moves the iterator to the next key.

Methods inherited from class java.lang.Object

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

Constructor Detail

ReusingKeyGroupedIterator

public ReusingKeyGroupedIterator(MutableObjectIterator<E> iterator,
                                 TypeSerializer<E> serializer,
                                 TypeComparator<E> comparator)

Initializes the KeyGroupedIterator. It requires an iterator which returns its result sorted by the key fields.

Parameters:

iterator - An iterator over records, which are sorted by the key fields, in any order.

serializer - The serializer for the data type iterated over.

comparator - The comparator for the data type iterated over.

Method Detail

nextKey

public boolean nextKey()
                throws IOException

Moves the iterator to the next key. This method may skip any values that have not yet been returned by the iterator created by the getValues() method. Hence, if called multiple times it "removes" pairs.

Specified by:

nextKey in interface KeyGroupedIterator<E>

Returns:

true if the input iterator has an other group of key-value pairs that share the same key.

Throws:

IOException

getComparatorWithCurrentReference

public TypeComparator<E> getComparatorWithCurrentReference()

getCurrent

public E getCurrent()

Specified by:

getCurrent in interface KeyGroupedIterator<E>

getValues

public ReusingKeyGroupedIterator.ValuesIterator getValues()

Returns an iterator over all values that belong to the current key. The iterator is initially null (before the first call to nextKey() and after all keys are consumed. In general, this method returns always a non-null value, if a previous call to nextKey() return true.

Specified by:

getValues in interface KeyGroupedIterator<E>

Returns:

Iterator over all values that belong to the current key.