org.sf.xrime.model.vertex.Vertex.java Source code

Introduction

Here is the source code for org.sf.xrime.model.vertex.Vertex.java

Source

/*
 * Copyright (C) IBM Corp. 2009.
 * 
 * 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 org.sf.xrime.model.vertex;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.util.Iterator;

import org.apache.hadoop.io.Text;
import org.apache.hadoop.io.Writable;
import org.apache.hadoop.io.WritableFactories;
import org.apache.hadoop.io.WritableFactory;
import org.sf.xrime.model.Element;
import org.sf.xrime.model.edge.AbstractEdge;

/**
 * Base class for vertexes in a graph.
 * @author xue
 */
public class Vertex implements Element, Cloneable {
    /**
     * Each vertex is identified with a string id.
     */
    protected String id = null;

    static {
        // Register the writable factory for this class.
        WritableFactories.setFactory(Vertex.class, new WritableFactory() {
            public Writable newInstance() {
                return new Vertex();
            }
        });
    }

    /**
     * Default constructor.
     */
    public Vertex() {

    }

    /**
     * Normal constructor.
     * @param id
     */
    public Vertex(String id) {
        this.id = id;
    }

    /**
     * Copy constructor.
     * @param vertex
     */
    public Vertex(Vertex vertex) {
        this.id = vertex.getId();
    }

    /**
     * Get the id of this vertex.
     * @return
     */
    public String getId() {
        return id;
    }

    /**
     * Set the id of this vertex.
     * @param id
     */
    public void setId(String id) {
        this.id = id;
    }

    public String toString() {
        return id;
    }

    @Override
    public void fromString(String encoding) {
        this.id = encoding;
    }

    public Object clone() {
        return new Vertex(this);
    }

    public void readFields(DataInput in) throws IOException {
        this.id = Text.readString(in);
    }

    public void write(DataOutput out) throws IOException {
        Text.writeString(out, id);
    }

    @Override
    public boolean equals(Object obj) {
        if (obj instanceof Vertex) {
            return id.equals(((Vertex) obj).getId());
        } else {
            return false;
        }
    }

    @Override
    public int hashCode() {
        return id.hashCode();
    }

    /* 
     * Since we do not really own any incident element, so hasNext() is always return false.
     * @see org.sf.xrime.model.Element#getIncidentElements()
     */
    @Override
    public Iterator<AbstractEdge> getIncidentElements() {
        /**
         * Use an internal class to implement customized iterator logic.
         */
        class Itr implements Iterator<AbstractEdge> {
            @Override
            public boolean hasNext() {
                return false;
            }

            @Override
            public AbstractEdge next() {
                return null;
            }

            @Override
            public void remove() {
                throw new UnsupportedOperationException("This is a read-only iterator");
            }
        }

        return new Itr();
    }

}