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BasicAggregator xref
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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  }