A String splitter utility class which ignores delimiters between quotes. Has no external dependencies.

QuoteAwareStringSplitter.java

/*
 * Copyright (c) 2012, Metron, Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *     * Neither the name of Metron, Inc. nor the
 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL METRON, INC. BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

public class QuoteAwareStringSplitter
{
	protected static final char QUOTE = '\"';
	protected static final char COMMA = ',';

	protected static enum ParseMode
	{
		BETWEEN_QUOTES, AFTER_END_QUOTE_BEFORE_COMMA, DEFAULT
	};

	public static String[] splitLine( String s ) throws IOException
	{
		return splitLine( s, COMMA, Integer.MAX_VALUE );
	}

	public static String[] splitLine( String s, char split ) throws IOException
	{
		return splitLine( s, split, Integer.MAX_VALUE );
	}

	public static String[] splitLine( String s, int limit ) throws IOException
	{
		return splitLine( s, COMMA, limit );
	}

	public static String[] splitLine( String s, char split, int limit ) throws IOException
	{
		final char[] line = s.toCharArray( );
		final int lineLength = s.length( );

		List<String> items = new ArrayList<String>( 20 );

		int itemStartPos = 0;
		ParseMode mode = QuoteAwareStringSplitter.ParseMode.DEFAULT;
		for ( int linePos = 0; linePos < lineLength; linePos++ )
		{
			if ( items.size( ) == limit - 1 )
			{
				linePos = lineLength - 1;
			}

			char c = line[linePos];

			if ( linePos == lineLength - 1 )
			{
				if ( c == QUOTE )
				{
					items.add( s.substring( itemStartPos, linePos ) );
				}
				else if ( c == split )
				{
					items.add( s.substring( itemStartPos, linePos ) );
					if ( items.size( ) < limit )
					{
						items.add( s.substring( 0, 0 ) );
					}
				}
				else
				{
					items.add( s.substring( itemStartPos, linePos + 1 ) );
				}
				break;
			}

			switch ( mode )
			{

			case BETWEEN_QUOTES:
				if ( c == QUOTE )
				{
					items.add( s.substring( itemStartPos, linePos ) );
					mode = QuoteAwareStringSplitter.ParseMode.AFTER_END_QUOTE_BEFORE_COMMA;
					itemStartPos = linePos + 1;
				}
				else if ( c == split )
				{
					// ignore, this is part of item between quotes
				}
				else
				{
					// ignore, part of item
				}
				break;

			case AFTER_END_QUOTE_BEFORE_COMMA:
				if ( c == QUOTE )
				{
					throw new IOException( String.format( "Unable to parse: \"%s\"", s ) );
				}
				else if ( c == split )
				{
					itemStartPos = linePos + 1;
					mode = QuoteAwareStringSplitter.ParseMode.DEFAULT;
				}
				else
				{
					// no-mans land, not part of item
				}
				break;

			case DEFAULT:
				if ( c == QUOTE )
				{
					itemStartPos = linePos + 1;
					mode = QuoteAwareStringSplitter.ParseMode.BETWEEN_QUOTES;
				}
				else if ( c == split )
				{
					items.add( s.substring( itemStartPos, linePos ) );
					itemStartPos = linePos + 1;
				}
				else
				{
					// ignore, part of item
				}
				break;

			default:
				throw new RuntimeException( String.format( "Unexpected state while parsing: \"%s\"", s ) );

			}
		}

		return items.toArray( new String[0] );
	}
}