Parse CSV line with regex - Java File Path IO

Java examples for File Path IO:CSV File

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Description

Parse CSV line with regex

Demo Code

/**//from ww  w  .  j av a 2  s  .  c om
 * Copyright ? 2010-2012 Atilika Inc.  All rights reserved.
 *
 * Atilika Inc. licenses this file to you under the Apache License, Version
 * 2.0 (the "License"); you may not use this file except in compliance with
 * the License.  A copy of the License is distributed with this work in the
 * LICENSE.txt file.  You may also obtain a copy of the License from
 * 
 *   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 com.java2s;
import java.util.ArrayList;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class Main {
    private static final char QUOTE = '"';
    private static final char COMMA = ',';
    private static final Pattern QUOTE_REPLACE_PATTERN = Pattern
            .compile("^\"([^\"]+)\"$");
    private static final String ESCAPED_QUOTE = "\"\"";

    /**
     * Parse CSV line
     * @param line
     * @return Array of values
     */
    public static String[] parse(String line) {
        boolean insideQuote = false;
        ArrayList<String> result = new ArrayList<String>();
        int quoteCount = 0;
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < line.length(); i++) {
            char c = line.charAt(i);

            if (c == QUOTE) {
                insideQuote = !insideQuote;
                quoteCount++;
            }

            if (c == COMMA && !insideQuote) {
                String value = sb.toString();
                value = unQuoteUnEscape(value);
                result.add(value);
                sb = new StringBuilder();
                continue;
            }

            sb.append(c);
        }

        result.add(sb.toString());

        // Validate
        if (quoteCount % 2 != 0) {
            return new String[0];
        }

        return result.toArray(new String[result.size()]);
    }

    private static String unQuoteUnEscape(String original) {
        String result = original;

        // Unquote
        Matcher m = QUOTE_REPLACE_PATTERN.matcher(original);
        if (m.matches()) {
            result = m.group(1);
        }

        // Unescape
        result = result.replaceAll(ESCAPED_QUOTE, "\"");

        return result;

    }
}

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