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Java example source code file (SimpleEdgesConnecting.java)

This example Java source code file (SimpleEdgesConnecting.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

abstractset, annotation, iterator, map, nullable, object, override, simpleedgesconnecting, util

The SimpleEdgesConnecting.java Java example source code

/*
 * Copyright (C) 2016 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.graph;

import static com.google.common.base.Preconditions.checkNotNull;

import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Iterators;

import java.util.AbstractSet;
import java.util.Iterator;
import java.util.Map;

import javax.annotation.Nullable;

/**
 * A class to represent the set of edges connecting an (implicit) origin node to a target node.
 *
 * <p>The {@link #nodeToEdgeMap} means this class only works on networks without parallel edges.
 *
 * @author James Sexton
 * @param <E> Edge parameter type
 */
final class SimpleEdgesConnecting<E> extends AbstractSet {

  private final Map<?, E> nodeToEdgeMap;
  private final Object targetNode;

  SimpleEdgesConnecting(Map<?, E> nodeToEdgeMap, Object targetNode) {
    this.nodeToEdgeMap = checkNotNull(nodeToEdgeMap);
    this.targetNode = checkNotNull(targetNode);
  }

  @Override
  public Iterator<E> iterator() {
    E connectingEdge = getConnectingEdge();
    return (connectingEdge == null)
        ? ImmutableSet.<E>of().iterator()
        : Iterators.singletonIterator(connectingEdge);
  }

  @Override
  public int size() {
    return getConnectingEdge() == null ? 0 : 1;
  }

  @Override
  public boolean contains(@Nullable Object obj) {
    E connectingEdge = getConnectingEdge();
    return (connectingEdge != null && connectingEdge.equals(obj));
  }

  @Nullable private E getConnectingEdge() {
    return nodeToEdgeMap.get(targetNode);
  }
}

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