The compareTo() method calls getRowNum() up to three times. Normally this isn’t a problem however the compareTo() method is called a lot - over three million times in my test case which uses a small Excel spreadsheet.

Using a local int to cache the values reduced the exection time by 26.3 seconds. Here is the new version of compareTo():

    public int compareTo(Object obj) {
        HSSFRow loc = (HSSFRow) obj;
        int rv = -1;
        int thisRowNum = this.getRowNum();
        int locRowNum = loc.getRowNum();

        if (thisRowNum == locRowNum) {
            rv = 0;
        } else if (thisRowNum < locRowNum) {
            rv = -1;
        } if (thisRowNum > locRowNum) {
            rv = 1;
        }
        return rv;
    }

My last post introduced a shortToConstructorCache class. This post shows a changed RecordFactory class that uses it. In my test case, I was able to reduce the execution time of RecordFactory.createRecord() by 3.6 seconds and reduce the number of objects created by 466,586.

/*
 * ====================================================================
 * Copyright 2002-2004 Apache Software Foundation
 *
 * 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.apache.poi.hssf.record;

import org.apache.poi.util.LittleEndian;
import org.wwre.common.shortToShortCache;

import java.io.IOException;
import java.io.InputStream;
import java.lang.reflect.Constructor;
import java.util.*;

/**
 * Title: Record Factory
 * 

 * Description: Takes a stream and outputs an array of Record objects.
 * 

 *
 * @deprecated use EventRecordFactory instead
 * @see org.apache.poi.hssf.eventmodel.EventRecordFactory
 * @author Andrew C. Oliver (acoliver at apache dot org)
 * @author Marc Johnson (mjohnson at apache dot org)
 * @author Glen Stampoultzis (glens at apache.org)
 * @author Csaba Nagy (ncsaba at yahoo dot com)
 * @version 1.0-pre
 */

public class RecordFactory {

    private static int                     NUM_RECORDS = 10000;

    private static shortToConstructorCache scm         = null;

    private static shortToShortCache       ssc         = new shortToShortCache();

    static {
        Class[] records;

        if (FormulaRecord.EXPERIMENTAL_FORMULA_SUPPORT_ENABLED) {
            records = new Class[] {
                BOFRecord.class, InterfaceHdrRecord.class, MMSRecord.class,
                InterfaceEndRecord.class, WriteAccessRecord.class, CodepageRecord.class, DSFRecord.class,
                TabIdRecord.class, FnGroupCountRecord.class, WindowProtectRecord.class, ProtectRecord.class,
                PasswordRecord.class,
                ProtectionRev4Record.class, PasswordRev4Record.class, WindowOneRecord.class, BackupRecord.class,
                HideObjRecord.class, DateWindow1904Record.class, PrecisionRecord.class, RefreshAllRecord.class,
                BookBoolRecord.class, FontRecord.class, FormatRecord.class, ExtendedFormatRecord.class,
                StyleRecord.class, UseSelFSRecord.class, BoundSheetRecord.class, CountryRecord.class,
                SSTRecord.class, ExtSSTRecord.class, EOFRecord.class, IndexRecord.class, CalcModeRecord.class,
                CalcCountRecord.class, RefModeRecord.class, IterationRecord.class, DeltaRecord.class,
                SaveRecalcRecord.class, PrintHeadersRecord.class, PrintGridlinesRecord.class, GridsetRecord.class,
                GutsRecord.class, DefaultRowHeightRecord.class, WSBoolRecord.class, HeaderRecord.class,
                FooterRecord.class, HCenterRecord.class, VCenterRecord.class, PrintSetupRecord.class,
                DefaultColWidthRecord.class, DimensionsRecord.class, RowRecord.class, LabelSSTRecord.class,
                RKRecord.class, NumberRecord.class, DBCellRecord.class, WindowTwoRecord.class,
                SelectionRecord.class, ContinueRecord.class, LabelRecord.class, BlankRecord.class,
                ColumnInfoRecord.class,	MulRKRecord.class, MulBlankRecord.class, MergeCellsRecord.class,
                FormulaRecord.class, BoolErrRecord.class, ExternSheetRecord.class, NameRecord.class,
                LeftMarginRecord.class, RightMarginRecord.class, TopMarginRecord.class, BottomMarginRecord.class,
                DrawingRecord.class, DrawingGroupRecord.class, DrawingSelectionRecord.class, ObjRecord.class,
                TextObjectRecord.class, PaletteRecord.class, StringRecord.class, RecalcIdRecord.class,
                SharedFormulaRecord.class, HorizontalPageBreakRecord.class, VerticalPageBreakRecord.class
            };
        } else {
            records = new Class[] {
                BOFRecord.class, InterfaceHdrRecord.class, MMSRecord.class, InterfaceEndRecord.class,
                WriteAccessRecord.class, CodepageRecord.class, DSFRecord.class, TabIdRecord.class,
                FnGroupCountRecord.class, WindowProtectRecord.class, ProtectRecord.class, PasswordRecord.class,
                ProtectionRev4Record.class, PasswordRev4Record.class, WindowOneRecord.class, BackupRecord.class,
                HideObjRecord.class, DateWindow1904Record.class, PrecisionRecord.class, RefreshAllRecord.class,
                BookBoolRecord.class, FontRecord.class, FormatRecord.class, ExtendedFormatRecord.class,
                StyleRecord.class, UseSelFSRecord.class, BoundSheetRecord.class, CountryRecord.class,
                SSTRecord.class, ExtSSTRecord.class, EOFRecord.class, IndexRecord.class, CalcModeRecord.class,
                CalcCountRecord.class, RefModeRecord.class, IterationRecord.class, DeltaRecord.class,
                SaveRecalcRecord.class, PrintHeadersRecord.class, PrintGridlinesRecord.class, GridsetRecord.class,
                GutsRecord.class, DefaultRowHeightRecord.class, WSBoolRecord.class, HeaderRecord.class,
                FooterRecord.class, HCenterRecord.class, VCenterRecord.class, PrintSetupRecord.class,
                DefaultColWidthRecord.class, DimensionsRecord.class, RowRecord.class, LabelSSTRecord.class,
                RKRecord.class, NumberRecord.class, DBCellRecord.class, WindowTwoRecord.class, SelectionRecord.class,
                ContinueRecord.class, LabelRecord.class, BlankRecord.class, ColumnInfoRecord.class,
                MulRKRecord.class, MulBlankRecord.class, MergeCellsRecord.class, BoolErrRecord.class,
                ExternSheetRecord.class, NameRecord.class, LeftMarginRecord.class, RightMarginRecord.class,
                TopMarginRecord.class, BottomMarginRecord.class, PaletteRecord.class, StringRecord.class,
                RecalcIdRecord.class, SharedFormulaRecord.class, DrawingRecord.class, DrawingGroupRecord.class,
                DrawingSelectionRecord.class, ObjRecord.class, TextObjectRecord.class, HorizontalPageBreakRecord.class,
                VerticalPageBreakRecord.class};
        }

        scm = new shortToConstructorCache(records);
    }

    /**
     * changes the default capacity (10000) to handle larger files
     */

    public static void setCapacity(int capacity) {
        NUM_RECORDS = capacity;
    }

    /**
     * Create an array of records from an input stream
     *
     * @param in the InputStream from which the records will be obtained
     *
     * @return an array of Records created from the InputStream
     *
     * @exception RecordFormatException on error processing the InputStream
     */

    public static List createRecords(InputStream in) throws RecordFormatException {
        ArrayList records = new ArrayList(NUM_RECORDS);
        Record last_record = null;

        try {
            short rectype = 0;

            do {
                rectype = LittleEndian.readShort(in);
                if (rectype != 0) {
                    short recsize = LittleEndian.readShort(in);
                    byte[] data = new byte[recsize];

                    in.read(data);
                    Record[] recs = createRecord(rectype, recsize, data); // handle MulRK records

                    if (recs.length > 1) {
                        for (int k = 0; k < recs.length; k++) {
                            records.add(recs[k]); // these will be number records
                            last_record = recs[k]; // do to keep the algorythm homogenous...you can't
                        } // actually continue a number record anyhow.
                    } else {
                        Record record = recs[0];

                        if (record != null) {
                            if (rectype == ContinueRecord.sid && !(last_record instanceof ContinueRecord) && // include continuation records after
                                    !(last_record instanceof UnknownRecord)) // unknown records or previous continuation records
                            {
                                if (last_record == null) {
                                    throw new RecordFormatException("First record is a ContinueRecord??");
                                }
                                last_record.processContinueRecord(data);
                            } else {
                                last_record = record;
                                records.add(record);
                            }
                        }
                    }
                }
            } while (rectype != 0);
        } catch (IOException e) {
            throw new RecordFormatException("Error reading bytes");
        }

        // Record[] retval = new Record[ records.size() ];
        // retval = ( Record [] ) records.toArray(retval);
        return records;
    }

    public static Record[] createRecord(short rectype, short size, byte[] data) {
        Record retval = null;
        Record[] realretval = null;

        try {
            Constructor constructor = scm.get(rectype);

            if (constructor != null) {
                retval = (Record) constructor.newInstance(new Object[] {ssc.get(rectype), ssc.get(size), data});
            } else {
                retval = new UnknownRecord(rectype, size, data);
            }
        } catch (Exception introspectionException) {
            introspectionException.printStackTrace();
            throw new RecordFormatException("Unable to construct record instance, the following exception occured: " +
                introspectionException.getMessage());
        }

        if (retval instanceof RKRecord) {
            RKRecord rk = (RKRecord) retval;
            NumberRecord num = new NumberRecord();

            num.setColumn(rk.getColumn());
            num.setRow(rk.getRow());
            num.setXFIndex(rk.getXFIndex());
            num.setValue(rk.getRKNumber());
            retval = num;
        } else if (retval instanceof DBCellRecord) {
            retval = null;
        } else if (retval instanceof MulRKRecord) {
            MulRKRecord mrk = (MulRKRecord) retval;

            realretval = new Record[mrk.getNumColumns()];
            for (int k = 0; k < mrk.getNumColumns(); k++) {
                NumberRecord nr = new NumberRecord();

                nr.setColumn((short) (k + mrk.getFirstColumn()));
                nr.setRow(mrk.getRow());
                nr.setXFIndex(mrk.getXFAt(k));
                nr.setValue(mrk.getRKNumberAt(k));
                realretval[k] = nr;
            }
        } else if (retval instanceof MulBlankRecord) {
            MulBlankRecord mb = (MulBlankRecord) retval;

            realretval = new Record[mb.getNumColumns()];
            for (int k = 0; k < mb.getNumColumns(); k++) {
                BlankRecord br = new BlankRecord();

                br.setColumn((short) (k + mb.getFirstColumn()));
                br.setRow(mb.getRow());
                br.setXFIndex(mb.getXFAt(k));
                realretval[k] = br;
            }
        }
        if (realretval == null) {
            realretval = new Record[1];
            realretval[0] = retval;
        }

        return realretval;
    }

    public static short[] getAllKnownRecordSIDs() {
        return scm.getTable();
    }

}
</pre>