cn.ac.ict.htc.tools.ArrayListWritable.java Source code

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Here is the source code for cn.ac.ict.htc.tools.ArrayListWritable.java

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/*
 * Cloud9: A MapReduce Library for Hadoop
 *
 * 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 edu.umd.cloud9.io.array;
package cn.ac.ict.htc.tools;

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

import org.apache.hadoop.io.Writable;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * <p>
 * Writable extension of a Java ArrayList. Elements in the list must be homogeneous and must
 * implement Hadoop's Writable interface.
 * </p>
 *
 * @param <E> type of list element
 *
 * @author Jimmy Lin
 * @author Tamer Elsayed
 */

public class ArrayListWritable<E extends Writable> extends ArrayList<E> implements Writable {
    private static final long serialVersionUID = 4911321393319821791L;
    private ArrayList elements;
    private static final Log logger = LogFactory.getLog(ArrayListWritable.class);

    /**
      * Creates an ArrayListWritable object.
      */
    public ArrayListWritable() {
        super();
    }

    /**
     * Creates an ArrayListWritable object from an ArrayList.
     */
    public ArrayListWritable(ArrayList<E> array) {
        super(array);
    }

    public ArrayList get() {
        return this;
    }

    //   public void set(ArrayList elements){
    //      this = elements;
    //   }
    /**
     * Deserializes the array.
     *
     * @param in source for raw byte representation
     */
    @SuppressWarnings("unchecked")
    public void readFields(DataInput in) throws IOException {
        this.clear();

        int numFields = in.readInt();
        if (numFields == 0)
            return;
        String className = in.readUTF();
        E obj;
        try {
            Class<E> c = (Class<E>) Class.forName(className);
            for (int i = 0; i < numFields; i++) {
                obj = (E) c.newInstance();
                obj.readFields(in);
                this.add(obj);
            }

        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * Serializes this array.
     *
     * @param out where to write the raw byte representation
     */
    public void write(DataOutput out) throws IOException {
        out.writeInt(this.size());
        //      logger.info("write " + this.size() + " elements");
        if (size() == 0)
            return;
        E obj = get(0);

        out.writeUTF(obj.getClass().getCanonicalName());

        //      for (int i = 0; i < size(); i++) {
        //         obj = get(i);
        //         if (obj == null) {
        //            throw new IOException("Cannot serialize null fields!");
        //         }
        //         obj.write(out);
        //      }
    }

    /**
     * Generates human-readable String representation of this ArrayList.
     *
     * @return human-readable String representation of this ArrayList
     */
    public String toString() {
        StringBuffer sb = new StringBuffer();
        sb.append("[");
        for (int i = 0; i < this.size(); i++) {
            if (i != 0)
                sb.append(", ");
            sb.append(this.get(i));
        }
        sb.append("]");

        return sb.toString();
    }
}