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Maven Package for datafile.sourceforge.net Java data file read/write utility that provides a convenient set of interfaces for reading and writing data to and from files in widely accepted format such as comma separated values (CSV), fixed width, tab separated, as well as others.
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/*
 * $Id: AbstractDataFile.java,v 1.2 2005/12/19 12:31:29 oldman1004 Exp $
 *
 * Copyright(c) 2002 Infomata
 * 
 * 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
 */
package com.infomata.data;

import java.text.NumberFormat;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Hashtable;
import java.util.Iterator;
import java.util.List;

/**
 * Abstract implementation of DataFile interface.  This class implements common methods
 * that do not differ in either reader or writer implementations.
 * 
 * @version $Revision: 1.2 $
 * @author Sam Kim
 *
 */
public abstract class AbstractDataFile implements DataFile
{

	/**
	 * Character encoding used for reading/writing a data file.
	 */
    private String enc = null;

    /**
     * Map of header (column label) to column index.
     */
    protected Hashtable headerIndex = null;

    /**
     * List of header names in column index sequence.
     */
    private ArrayList headerList = null;

    /**
     * Instance of NumberFormat used to parse or format numeric data.
     */
    protected NumberFormat nf = null;

    /**
     * Implementation of DataFormat for parsing/formatting data from/into
     * a data file in specified format.
     */
    protected DataFormat format = null;

    /**
     * Check if character encoding has been set.
     * @return true if set.  false otherwise.
     */
    protected boolean containsCharacterEncoding()
    {
        return enc != null && enc.length() > 0;
    }

    /**
     * Retrieve character encoding for current instance of DataFile.
     * @return character encoding.
     */
    protected String getCharacterEncoding()
    {
        return enc;
    }

    /**
     * Sets the character encoding for current instance of DataFile.
     * @param enc supported character encoding.
     */
    protected void setCharacterEncoding(String enc)
    {
        this.enc = enc;
    }

    /*
     * (non-Javadoc)
     * @see com.infomata.data.DataFile#containsHeader(boolean)
     */
    public final void containsHeader(boolean header)
    {
        headerList = (header) ? new ArrayList() : null;
    }

    /*
     * (non-Javadoc)
     * @see com.infomata.data.DataFile#containsHeader()
     */
    public final boolean containsHeader()
    {
        return headerList != null;
    }

    /*
     * (non-Javadoc)
     * @see com.infomata.data.DataFile#setDataFormat(com.infomata.data.DataFormat)
     */
    public final void setDataFormat(DataFormat format)
    {
        this.format = format;
    }

    /**
     * Retrieves the list of header names found in the first row of the data
     * file. In order for this to work, the header row indicator must be set
     * prior to opening the data file. Note: the header names are not
     * guaranteed to be the order they appear in the first row of the data file.
     * 
     * @return header names (not guaranteed in the order in which they appear in
     *         file).
     * @deprecated use {@link #getHeaderList()} instead.
     */
    public final Iterator getHeaderNames()
    {
        ArrayList tmp = (headerIndex == null) ? new ArrayList()
                : new ArrayList(headerIndex.keySet());
        return tmp.iterator();
    }

    /*
     * (non-Javadoc)
     * @see com.infomata.data.DataFile#getHeaderList()
     */
    public final List getHeaderList()
    {
        return Collections.unmodifiableList(headerList);
    }

    /*
     * (non-Javadoc)
     * @see com.infomata.data.DataFile#setHeaderList(java.util.List)
     */
    public void setHeaderList(List headers)
    {
        // for cases when header is manually set.
        if (containsHeader())
        {
            resetHeaders();
        }
        else
        {
            containsHeader(true);
        }

        headerIndex = new Hashtable(headers.size());
        for (int i = 0; i < headers.size(); i++)
        {
            headerList.add(headers.get(i).toString());
            headerIndex.put(headers.get(i).toString(), new Integer(i));
        }
    }

    /**
     * Removes header row (column labels) from the DataFile instance.
     */
    protected void resetHeaders()
    {
        if (containsHeader())
        {
            headerList.clear();
            if (headerIndex != null)
            {
                headerIndex.clear();
                headerIndex = null;
            }
        }
    }

    /* (non-Javadoc)
     * @see com.infomata.data.DataFile#setNumberFormat(java.text.NumberFormat)
     */
    public void setNumberFormat(NumberFormat numberFormat)
    {
        nf = numberFormat;
    }

}