org.apache.kafka.streams.kstream.ValueJoiner Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.kafka.streams.kstream;
/**
* The {@code ValueJoiner} interface for joining two values into a new value of arbitrary type.
* This is a stateless operation, i.e, {@link #apply(Object, Object)} is invoked individually for each joining
* record-pair of a {@link KStream}-{@link KStream}, {@link KStream}-{@link KTable}, or {@link KTable}-{@link KTable}
* join.
*
* @param first value type
* @param second value type
* @param joined value type
* @see KStream#join(KStream, ValueJoiner, JoinWindows)
* @see KStream#join(KStream, ValueJoiner, JoinWindows, StreamJoined)
* @see KStream#leftJoin(KStream, ValueJoiner, JoinWindows)
* @see KStream#leftJoin(KStream, ValueJoiner, JoinWindows, StreamJoined)
* @see KStream#outerJoin(KStream, ValueJoiner, JoinWindows)
* @see KStream#outerJoin(KStream, ValueJoiner, JoinWindows, StreamJoined)
* @see KStream#join(KTable, ValueJoiner)
* @see KStream#join(KTable, ValueJoiner, Joined)
* @see KStream#leftJoin(KTable, ValueJoiner)
* @see KStream#leftJoin(KTable, ValueJoiner, Joined)
* @see KTable#join(KTable, ValueJoiner)
* @see KTable#leftJoin(KTable, ValueJoiner)
* @see KTable#outerJoin(KTable, ValueJoiner)
*/
public interface ValueJoiner {
/**
* Return a joined value consisting of {@code value1} and {@code value2}.
*
* @param value1 the first value for joining
* @param value2 the second value for joining
* @return the joined value
*/
VR apply(final V1 value1, final V2 value2);
}