IdAndNullArrayEdges implements ReuseObjectsOutEdges<I, NullWritable>,
  MutableOutEdges<I, NullWritable>,
  ImmutableClassesGiraphConfigurable<I, Writable, NullWritable> { @Override public void initialize(Iterable<Edge<I, NullWritable>> edges) { EdgeIterables.initialize(this, edges); }  @Override ImmutableClassesGiraphConfiguration<I, Writable, NullWritable> getConf(); @Override void setConf(
      ImmutableClassesGiraphConfiguration<I, Writable, NullWritable> conf); @Override void initialize(Iterable<Edge<I, NullWritable>> edges); @Override void initialize(int capacity); @Override void initialize(); @Override void add(Edge<I, NullWritable> edge); @Override void remove(I targetVertexId); @Override int size(); @Override Iterator<Edge<I, NullWritable>> iterator(); @Override Iterator<MutableEdge<I, NullWritable>> mutableIterator(); @Override void write(DataOutput out); @Override void readFields(DataInput in);  }
@Test public void testInitialize() { IdAndNullArrayEdges edges = getEdges(); List<Edge<LongWritable, NullWritable>> initialEdges = Lists.newArrayList( createEdge(1), createEdge(2), createEdge(4)); edges.initialize(initialEdges); assertEdges(edges, 1, 2, 4); edges.add(EdgeFactory.createReusable(new LongWritable(3))); assertEdges(edges, 1, 2, 4, 3); edges.initialize(); assertEquals(0, edges.size()); }