AverageAggregateBuilder.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.metamodel.query;

import org.apache.metamodel.util.AbstractNumberAggregateBuilder;

/**
 * Aggregate builder for the {@link FunctionType#AVG} function
 */
final class AverageAggregateBuilder extends AbstractNumberAggregateBuilder<Double> {

	public double _average;
	public int _numValues;
	
	@Override
	protected void add(Number number) {
		double total = _average * _numValues + number.doubleValue();
		_numValues++;
		_average = total / _numValues;
	}

	@Override
	public Double getAggregate() {
		return _average;
	}

}