1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one 3 * or more contributor license agreements. See the NOTICE file 4 * distributed with this work for additional information 5 * regarding copyright ownership. The ASF licenses this file 6 * to you under the Apache License, Version 2.0 (the 7 * "License"); you may not use this file except in compliance 8 * with the License. You may obtain a copy of the License at 9 * 10 * http://www.apache.org/licenses/LICENSE-2.0 11 * 12 * Unless required by applicable law or agreed to in writing, software 13 * distributed under the License is distributed on an "AS IS" BASIS, 14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 15 * See the License for the specific language governing permissions and 16 * limitations under the License. 17 */ 18 19 package org.apache.giraph.aggregators; 20 21 import org.apache.hadoop.io.Writable; 22 23 /** 24 * Abstract class for {@link Aggregator}. 25 * Implements get value, set value and reset methods and has internal value 26 * object. 27 * 28 * @param <A> Aggregated value 29 */ 30 public abstract class BasicAggregator<A extends Writable> implements 31 Aggregator<A> { 32 /** Internal value */ 33 private A value; 34 35 /** 36 * Default constructor. 37 * Creates new value object and resets the aggregator 38 */ 39 public BasicAggregator() { 40 value = createInitialValue(); 41 } 42 43 /** 44 * Constructor 45 * @param initialValue initial value 46 */ 47 public BasicAggregator(A initialValue) { 48 value = initialValue; 49 } 50 51 52 @Override 53 public A getAggregatedValue() { 54 return value; 55 } 56 57 @Override 58 public void setAggregatedValue(A value) { 59 this.value = value; 60 } 61 62 @Override 63 public void reset() { 64 value = createInitialValue(); 65 } 66 }