/* * 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; import org.apache.kafka.common.annotation.InterfaceStability; /** * 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 <V1> first value type * @param <V2> second value type * @param <VR> joined value type * @see KStream#join(KStream, ValueJoiner, JoinWindows) * @see KStream#join(KStream, ValueJoiner, JoinWindows, org.apache.kafka.common.serialization.Serde, org.apache.kafka.common.serialization.Serde, org.apache.kafka.common.serialization.Serde) * @see KStream#leftJoin(KStream, ValueJoiner, JoinWindows) * @see KStream#leftJoin(KStream, ValueJoiner, JoinWindows, org.apache.kafka.common.serialization.Serde, org.apache.kafka.common.serialization.Serde, org.apache.kafka.common.serialization.Serde) * @see KStream#outerJoin(KStream, ValueJoiner, JoinWindows) * @see KStream#outerJoin(KStream, ValueJoiner, JoinWindows, org.apache.kafka.common.serialization.Serde, org.apache.kafka.common.serialization.Serde, org.apache.kafka.common.serialization.Serde) * @see KStream#join(KTable, ValueJoiner) * @see KStream#join(KTable, ValueJoiner, org.apache.kafka.common.serialization.Serde, org.apache.kafka.common.serialization.Serde) * @see KStream#leftJoin(KTable, ValueJoiner) * @see KStream#leftJoin(KTable, ValueJoiner, org.apache.kafka.common.serialization.Serde, org.apache.kafka.common.serialization.Serde) * @see KTable#join(KTable, ValueJoiner) * @see KTable#leftJoin(KTable, ValueJoiner) * @see KTable#outerJoin(KTable, ValueJoiner) */ @InterfaceStability.Unstable public interface ValueJoiner<V1, V2, VR> { /** * 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); }