flink-core/src/main/java/org/apache/flink/api/common/typeinfo/NothingTypeInfo.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.common.typeinfo;

import org.apache.flink.annotation.Public;
import org.apache.flink.annotation.PublicEvolving;
import org.apache.flink.api.common.ExecutionConfig;
import org.apache.flink.api.common.typeutils.TypeSerializer;
import org.apache.flink.types.Nothing;

/**
 * Placeholder type information for the {@link Nothing} type.
 */
@Public
public class NothingTypeInfo extends TypeInformation<Nothing> {

	private static final long serialVersionUID = 1L;

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

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

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

	@Override
	@PublicEvolving
	public int getTotalFields() {
		return 0;
	}

	@Override
	@PublicEvolving
	public Class<Nothing> getTypeClass() {
		return Nothing.class;
	}

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

	@Override
	@PublicEvolving
	public TypeSerializer<Nothing> createSerializer(ExecutionConfig executionConfig) {
		throw new RuntimeException("The Nothing type cannot have a serializer.");
	}

	@Override
	public String toString() {
		return getClass().getSimpleName();
	}

	@Override
	public boolean equals(Object obj) {
		if (obj instanceof NothingTypeInfo) {
			NothingTypeInfo nothingTypeInfo = (NothingTypeInfo) obj;

			return nothingTypeInfo.canEqual(this);
		} else {
			return false;
		}
	}

	@Override
	public int hashCode() {
		return NothingTypeInfo.class.hashCode();
	}

	@Override
	public boolean canEqual(Object obj) {
		return obj instanceof NothingTypeInfo;
	}
}