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EdgeNoValue 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.NullWritable;
22  import org.apache.hadoop.io.WritableComparable;
23  
24  /**
25   * An edge that has no value.
26   *
27   * @param <I> Vertex ID
28   */
29  public class EdgeNoValue<I extends WritableComparable>
30      implements ReusableEdge<I, NullWritable> {
31    /** Target vertex id */
32    private I targetVertexId = null;
33  
34    /** Empty constructor */
35    EdgeNoValue() { }
36  
37    /**
38     * Constructor with target vertex ID. Don't call, use EdgeFactory instead.
39     *
40     * @param targetVertexId vertex ID
41     */
42    EdgeNoValue(I targetVertexId) {
43      this.targetVertexId = targetVertexId;
44    }
45  
46    @Override
47    public void setTargetVertexId(I targetVertexId) {
48      this.targetVertexId = targetVertexId;
49    }
50  
51    @Override
52    public void setValue(NullWritable value) {
53      // do nothing
54    }
55  
56    @Override
57    public I getTargetVertexId() {
58      return targetVertexId;
59    }
60  
61    @Override
62    public NullWritable getValue() {
63      return NullWritable.get();
64    }
65  
66    @Override
67    public String toString() {
68      return "(targetVertexId = " + targetVertexId + ")";
69    }
70  }