Java String Split split(String str)

Description

Split a string using the default separator

License

Apache License

Parameter

Parameter	Description
str	a string that may have escaped separator

Return

an array of strings

Declaration

public static String[] split(String str) 

Method Source Code

//package com.java2s;
/*/* w  ww.j a  v a 2s .  co m*/
 *
 *  * Copyright 2015 Skymind,Inc.
 *  *
 *  *    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.
 *
 */

import java.util.*;

public class Main {
    final public static char COMMA = ',';
    final public static char ESCAPE_CHAR = '\\';

    /**
     * Split a string using the default separator
     * @param str a string that may have escaped separator
     * @return an array of strings
     */
    public static String[] split(String str) {
        return split(str, ESCAPE_CHAR, COMMA);
    }

    /**
     * Split a string using the given separator
     * @param str a string that may have escaped separator
     * @param escapeChar a char that be used to escape the separator
     * @param separator a separator char
     * @return an array of strings
     */
    public static String[] split(String str, char escapeChar, char separator) {
        if (str == null) {
            return null;
        }
        ArrayList<String> strList = new ArrayList<>();
        StringBuilder split = new StringBuilder();
        int index = 0;
        while ((index = findNext(str, separator, escapeChar, index, split)) >= 0) {
            ++index; // move over the separator for next search
            strList.add(split.toString());
            split.setLength(0); // reset the buffer
        }
        strList.add(split.toString());
        // remove trailing empty split(s)
        int last = strList.size(); // last split
        while (--last >= 0 && "".equals(strList.get(last))) {
            strList.remove(last);
        }
        return strList.toArray(new String[strList.size()]);
    }

    /**
     * Finds the first occurrence of the separator character ignoring the escaped
     * separators starting from the index. Note the substring between the index
     * and the position of the separator is passed.
     * @param str the source string
     * @param separator the character to find
     * @param escapeChar character used to escape
     * @param start from where to search
     * @param split used to pass back the extracted string
     */
    public static int findNext(String str, char separator, char escapeChar,
            int start, StringBuilder split) {
        int numPreEscapes = 0;
        for (int i = start; i < str.length(); i++) {
            char curChar = str.charAt(i);
            if (numPreEscapes == 0 && curChar == separator) { // separator
                return i;
            } else {
                split.append(curChar);
                numPreEscapes = (curChar == escapeChar) ? (++numPreEscapes) % 2
                        : 0;
            }
        }
        return -1;
    }
}

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