Java tutorial
package de.kp.core.spade.hadoop; /* Copyright (c) 2014 Dr. Krusche & Partner PartG * * This file is part of the Core-SPADE project * (https://github.com/skrusche63/core-spade). * * Core-SPADE is free software: you can redistribute it and/or modify it under the * terms of the GNU General Public License as published by the Free Software * Foundation, either version 3 of the License, or (at your option) any later * version. * * Core-SPADE is distributed in the hope that it will be useful, but WITHOUT ANY * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR * A PARTICULAR PURPOSE. See the GNU General Public License for more details. * You should have received a copy of the GNU General Public License along with * Core-SPADE. * * If not, see <http://www.gnu.org/licenses/>. */ import java.io.DataInput; import java.io.DataOutput; import java.io.IOException; import java.util.ArrayList; import java.util.Collections; import java.util.List; import org.apache.hadoop.io.ArrayWritable; import org.apache.hadoop.io.IntWritable; import org.apache.hadoop.io.Writable; import de.kp.core.spade.Itemset; import de.kp.core.spade.Sequence; public class SequenceWritable implements Writable { private IntWritable idWritable; private ArrayWritable itemsetListWritable; public SequenceWritable() { idWritable = new IntWritable(); List<ItemsetWritable> empty = Collections.<ItemsetWritable>emptyList(); itemsetListWritable = new ArrayWritable(ItemsetWritable.class, empty.toArray(new Writable[empty.size()])); } public SequenceWritable(Sequence sequence) { idWritable = new IntWritable(sequence.getId()); List<Itemset> itemsets = sequence.getItemsets(); ArrayList<ItemsetWritable> itemsetWritableList = new ArrayList<ItemsetWritable>(); for (int i = 0; i < itemsets.size(); i++) { itemsetWritableList.add(new ItemsetWritable(itemsets.get(i))); } this.itemsetListWritable = new ArrayWritable(ItemsetWritable.class, itemsetWritableList.toArray(new Writable[itemsetWritableList.size()])); } /* (non-Javadoc) * @see org.apache.hadoop.io.Writable#readFields(java.io.DataInput) */ @Override public void readFields(DataInput in) throws IOException { idWritable.readFields(in); itemsetListWritable.readFields(in); } /* (non-Javadoc) * @see org.apache.hadoop.io.Writable#write(java.io.DataOutput) */ @Override public void write(DataOutput out) throws IOException { idWritable.write(out); itemsetListWritable.write(out); } public Sequence get() { Sequence sequence = new Sequence(idWritable.get()); Writable[] writableArray = itemsetListWritable.get(); for (int i = 0; i < writableArray.length; i++) { ItemsetWritable itemset = (ItemsetWritable) writableArray[i]; sequence.addItemset(itemset.get()); } return sequence; } }