MapTypeInfo.java

/*
 * 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.flink.api.java.typeutils;

import org.apache.flink.annotation.PublicEvolving;
import org.apache.flink.api.common.ExecutionConfig;
import org.apache.flink.api.common.typeinfo.TypeInformation;
import org.apache.flink.api.common.typeutils.TypeSerializer;
import org.apache.flink.api.common.typeutils.base.MapSerializer;
import org.apache.flink.util.Preconditions;

import java.util.Map;

import static org.apache.flink.util.Preconditions.checkNotNull;

/**
 * Special {@code TypeInformation} used by {@link org.apache.flink.api.common.state.MapStateDescriptor}.
 * 
 * @param <K> The type of the keys in the map.
 * @param <V> The type of the values in the map.
 */
@PublicEvolving
public class MapTypeInfo<K, V> extends TypeInformation<Map<K, V>> {

	/* The type information for the keys in the map*/
	private final TypeInformation<K> keyTypeInfo;

	/* The type information for the values in the map */
	private final TypeInformation<V> valueTypeInfo;

	public MapTypeInfo(TypeInformation<K> keyTypeInfo, TypeInformation<V> valueTypeInfo) {
		this.keyTypeInfo = Preconditions.checkNotNull(keyTypeInfo, "The key type information cannot be null.");
		this.valueTypeInfo = Preconditions.checkNotNull(valueTypeInfo, "The value type information cannot be null.");
	}
	
	public MapTypeInfo(Class<K> keyClass, Class<V> valueClass) {
		this.keyTypeInfo = of(checkNotNull(keyClass, "The key class cannot be null."));
		this.valueTypeInfo = of(checkNotNull(valueClass, "The value class cannot be null."));
	}

	// ------------------------------------------------------------------------
	//  MapTypeInfo specific properties
	// ------------------------------------------------------------------------

	/**
	 * Gets the type information for the keys in the map
	 */
	public TypeInformation<K> getKeyTypeInfo() {
		return keyTypeInfo;
	}

	/**
	 * Gets the type information for the values in the map
	 */
	public TypeInformation<V> getValueTypeInfo() {
		return valueTypeInfo;
	}

	// ------------------------------------------------------------------------
	//  TypeInformation implementation
	// ------------------------------------------------------------------------

	@Override
	public boolean isBasicType() {
		return false;
	}

	@Override
	public boolean isTupleType() {
		return false;
	}

	@Override
	public int getArity() {
		return 0;
	}

	@Override
	public int getTotalFields() {
		return 1;
	}

	@SuppressWarnings("unchecked")
	@Override
	public Class<Map<K, V>> getTypeClass() {
		return (Class<Map<K, V>>)(Class<?>)Map.class;
	}

	@Override
	public boolean isKeyType() {
		return false;
	}

	@Override
	public TypeSerializer<Map<K, V>> createSerializer(ExecutionConfig config) {
		TypeSerializer<K> keyTypeSerializer = keyTypeInfo.createSerializer(config);
		TypeSerializer<V> valueTypeSerializer = valueTypeInfo.createSerializer(config);
		
		return new MapSerializer<>(keyTypeSerializer, valueTypeSerializer);
	}

	@Override
	public String toString() {
		return "Map<" + keyTypeInfo + ", " + valueTypeInfo + ">";
	}

	@Override
	public boolean equals(Object obj) {
		if (obj == this) {
			return true;
		} else if (obj instanceof MapTypeInfo) {
			@SuppressWarnings("unchecked")
			MapTypeInfo<K, V> other = (MapTypeInfo<K, V>) obj;
			
			return (other.canEqual(this) && 
					keyTypeInfo.equals(other.keyTypeInfo) && valueTypeInfo.equals(other.valueTypeInfo));
		} else {
			return false;
		}
	}

	@Override
	public int hashCode() {
		return 31 * keyTypeInfo.hashCode() + valueTypeInfo.hashCode();
	}

	@Override
	public boolean canEqual(Object obj) {
		return (obj != null && obj.getClass() == getClass());
	}
}