IndexMerger java implemention

package ucy.cs.hpcl.minerSoft.indexmanipulation;

/*This program 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.

This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.

Author: Asterios Katsifodimos (http://www.asteriosk.gr)
*/
import java.io.File;
import java.io.IOException;
import java.util.Date;

import org.apache.lucene.analysis.standard.StandardAnalyzer;
import org.apache.lucene.index.IndexWriter;
import org.apache.lucene.store.Directory;
import org.apache.lucene.store.FSDirectory;

public class IndexMerger {

 
 /** Index all text files under a directory. */
 public static void main(String[] args) {

  if(args.length != 2){
   System.out.println("Usage: java -jar IndexMerger.jar " +
                "existing_indexes_dir merged_index_dir");
   System.out.println(" existing_indexes_dir: A directory where the " +
                  "indexes that have to merged exist");
   System.out.println("   e.g. indexes/");
   System.out.println("   e.g.         index1");
   System.out.println("   e.g.         index2");
   System.out.println("   e.g.         index3");
   System.out.println(" merged_index_dir: A directory where the merged " +
                                    "index will be stored");
   System.out.println("   e.g. merged_indexes");
   System.exit(1);
  }
  
  File INDEXES_DIR  = new File(args[0]);
  File INDEX_DIR    = new File(args[1]);

  INDEX_DIR.mkdir();
  
  Date start = new Date();

  try {
   IndexWriter writer = new IndexWriter(INDEX_DIR, 
            new StandardAnalyzer(), 
            true);
   writer.setMergeFactor(1000);
   writer.setRAMBufferSizeMB(50);
   
   Directory indexes[] = new Directory[INDEXES_DIR.list().length];

   for (int i = 0; i < INDEXES_DIR.list().length; i++) {
    System.out.println("Adding: " + INDEXES_DIR.list()[i]);
    indexes[i] = FSDirectory.getDirectory(INDEXES_DIR.getAbsolutePath() 
             + "/" + INDEXES_DIR.list()[i]);
   }

   System.out.print("Merging added indexes...");
   writer.addIndexes(indexes);
   System.out.println("done");

   System.out.print("Optimizing index...");
   writer.optimize();
   writer.close();
   System.out.println("done");

   Date end = new Date();
   System.out.println("It took: "+((end.getTime() - start.getTime()) / 1000) 
           + "\"");

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