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MapMutableEdge 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.edge;
20  
21  import org.apache.hadoop.io.Writable;
22  import org.apache.hadoop.io.WritableComparable;
23  
24  import java.util.Map;
25  
26  /**
27   * Helper class for a mutable edge that modifies the backing map entry.
28   *
29   * @param <I> Vertex id
30   * @param <E> Edge value
31   */
32  public class MapMutableEdge<I extends WritableComparable, E extends Writable>
33      implements MutableEdge<I, E> {
34    /** Backing entry for the edge in the map. */
35    private Map.Entry<I, E> entry;
36  
37    /**
38     * Set the backing entry for this edge in the map.
39     *
40     * @param entry Backing entry
41     */
42    public void setEntry(Map.Entry<I, E> entry) {
43      this.entry = entry;
44    }
45  
46    @Override
47    public void setValue(E value) {
48      // Replace the value in the map.
49      entry.setValue(value);
50    }
51  
52    @Override
53    public I getTargetVertexId() {
54      return entry.getKey();
55    }
56  
57    @Override
58    public E getValue() {
59      return entry.getValue();
60    }
61  }