org.apache.flink.streaming.api.datastream

Class DataStreamUtils

java.lang.Object

org.apache.flink.streaming.api.datastream.DataStreamUtils

@Experimental
public final class DataStreamUtils
extends Object

A collection of utilities for DataStreams.

Method Summary

Modifier and Type	Method and Description
static <OUT> Iterator<OUT>	collect(DataStream<OUT> stream) Returns an iterator to iterate over the elements of the DataStream.
static <T,K> KeyedStream<T,K>	reinterpretAsKeyedStream(DataStream<T> stream, org.apache.flink.api.java.functions.KeySelector<T,K> keySelector) Reinterprets the given DataStream as a KeyedStream, which extracts keys with the given KeySelector.
static <T,K> KeyedStream<T,K>	reinterpretAsKeyedStream(DataStream<T> stream, org.apache.flink.api.java.functions.KeySelector<T,K> keySelector, org.apache.flink.api.common.typeinfo.TypeInformation<K> typeInfo) Reinterprets the given DataStream as a KeyedStream, which extracts keys with the given KeySelector.

Methods inherited from class java.lang.Object

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

Method Detail

collect

public static <OUT> Iterator<OUT> collect(DataStream<OUT> stream)
                                   throws IOException

Returns an iterator to iterate over the elements of the DataStream.

Returns:

The iterator

Throws:

IOException

reinterpretAsKeyedStream

public static <T,K> KeyedStream<T,K> reinterpretAsKeyedStream(DataStream<T> stream,
                                                              org.apache.flink.api.java.functions.KeySelector<T,K> keySelector)

Reinterprets the given DataStream as a KeyedStream, which extracts keys with the given KeySelector.

IMPORTANT: For every partition of the base stream, the keys of events in the base stream must be partitioned exactly in the same way as if it was created through a DataStream.keyBy(KeySelector).

Type Parameters:

T - Type of events in the data stream.

K - Type of the extracted keys.

Parameters:

stream - The data stream to reinterpret. For every partition, this stream must be partitioned exactly in the same way as if it was created through a DataStream.keyBy(KeySelector).

keySelector - Function that defines how keys are extracted from the data stream.

Returns:

The reinterpretation of the DataStream as a KeyedStream.

reinterpretAsKeyedStream

public static <T,K> KeyedStream<T,K> reinterpretAsKeyedStream(DataStream<T> stream,
                                                              org.apache.flink.api.java.functions.KeySelector<T,K> keySelector,
                                                              org.apache.flink.api.common.typeinfo.TypeInformation<K> typeInfo)

Reinterprets the given DataStream as a KeyedStream, which extracts keys with the given KeySelector.

IMPORTANT: For every partition of the base stream, the keys of events in the base stream must be partitioned exactly in the same way as if it was created through a DataStream.keyBy(KeySelector).

Type Parameters:

T - Type of events in the data stream.

K - Type of the extracted keys.

Parameters:

stream - The data stream to reinterpret. For every partition, this stream must be partitioned exactly in the same way as if it was created through a DataStream.keyBy(KeySelector).

keySelector - Function that defines how keys are extracted from the data stream.

typeInfo - Explicit type information about the key type.

Returns:

The reinterpretation of the DataStream as a KeyedStream.