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com.hfg xml, html, svg, and bioinformatics utility library
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package com.hfg.sql.table;

import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;

import com.hfg.xml.XMLTag;

//------------------------------------------------------------------------------
/**
 Database row object which has Long as a primary key.
 
 @author J. Alex Taylor, hairyfatguy.com
 
 */
//------------------------------------------------------------------------------
// com.hfg XML/HTML Coding Library
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library 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
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
//
// J. Alex Taylor, President, Founder, CEO, COO, CFO, OOPS hairyfatguy.com
// [email protected]
//------------------------------------------------------------------------------

public abstract class DatabaseRowWithLongPrimaryKey extends DatabaseRow
{

   // Cached value
   private Long mRowId;

   //###########################################################################
   // CONSTRUCTORS
   //###########################################################################

   //---------------------------------------------------------------------------
   public DatabaseRowWithLongPrimaryKey(DatabaseTable inTable)
   {
      super(inTable);
   }

   //---------------------------------------------------------------------------
   public DatabaseRowWithLongPrimaryKey(DatabaseTable inTable, ResultSet inResultSet)
   {
      super(inTable, inResultSet);
   }

   //---------------------------------------------------------------------------
   public DatabaseRowWithLongPrimaryKey(XMLTag inXMLTag)
   {
      super(inXMLTag);
   }


   //###########################################################################
   // PUBLIC METHODS
   //###########################################################################

   //---------------------------------------------------------------------------
   public Long getId()
   {
      if (null == mRowId)
      {
         mRowId = (Long) getField(getIdCol()).getValue();
      }

      return mRowId;
   }

   //---------------------------------------------------------------------------
   @SuppressWarnings("unchecked")
   public void clearId()
   {
      getField(getIdCol()).setValue(null);
      mRowId = null;
   }

   //---------------------------------------------------------------------------
   /**
    Searches a List of DatabaseRowWithLongPrimaryKey objects sorted in ascending order
    to find the matching row with the specified id. Slower than a HashMap approach
    but more memory efficient. More performant when used with ArrayLists than with LinkedLists.
    * @param inList the sorted List to be searched
    * @param inTargetRowId the row id to be searched for
    * @return the index of the row with the matching rowId or -1 if it is not present in the list
    */
   public static int interpolationSearch(List inList,
                                         Long inTargetRowId)
   {
      int listSize = inList.size();
      int leftIdx = 0;
      int rightIdx = inList.size() - 1;

      DatabaseRowWithLongPrimaryKey leftRow  = inList.get(leftIdx);
      DatabaseRowWithLongPrimaryKey rightRow = inList.get(rightIdx);

      while (leftIdx < rightIdx)
      {
         // Guess where to check next
         int nextIdx = leftIdx + (int) ((inTargetRowId - leftRow.getId()) * (rightIdx - leftIdx) /
                                        (rightRow.getId() - leftRow.getId()));

         if (nextIdx < 0)
         {
            nextIdx = 0;
         }
         else if (nextIdx >= listSize)
         {
            nextIdx = listSize - 1;
         }

         long comparison = inTargetRowId - inList.get(nextIdx).getId();
         if (0 == comparison)
         {
            return nextIdx;
         }
         else if (comparison < 0)
         {
            if (nextIdx <= 0
                || rightIdx <= nextIdx - 1)
            {
               break; // Or we'll end up in an infinite loop
            }

            rightIdx = nextIdx - 1;
            rightRow = inList.get(rightIdx);
         }
         else
         {
            if (nextIdx == listSize - 1
                || leftIdx >= nextIdx + 1)
            {
               break; // Or we'll end up in an infinite loop
            }

            leftIdx = nextIdx + 1;
            leftRow = inList.get(leftIdx);
         }
      }

      return (inTargetRowId.equals(leftRow.getId()) ? leftIdx : -1);
   }

}