Java Array Normalize normalizeSpaces(char[] buf, int origStart, int origEnd)

Description

Method that will check character array passed, and remove all "extra" spaces (leading and trailing space), and normalize other white space (more than one consequtive space character replaced with a single space).

License

Apache License

Parameter

Parameter	Description
buf	Buffer that contains the String to check
origStart	Offset of the first character of the text to check in the buffer
origEnd	Offset of the character following the last character of the text (as per usual Java API convention)

Return

Normalized String, if any white space was removed or normalized; null if no changes were necessary.

Declaration

public static String normalizeSpaces(char[] buf, int origStart, int origEnd)

Method Source Code

//package com.java2s;
//License from project: Apache License 

public class Main {
    final static char CHAR_SPACE = ' ';

    /**//from  w  w w.  j  a va 2  s  .  c o  m
     * Method that will check character array passed, and remove all
     * "extra" spaces (leading and trailing space), and normalize
     * other white space (more than one consequtive space character
     * replaced with a single space).
     *<p>
     * NOTE: we only remove explicit space characters (char code 0x0020);
     * the reason being that other white space must have come from
     * non-normalizable sources, ie. via entity expansion, and is thus
     * not to be normalized
     *
     * @param buf Buffer that contains the String to check
     * @param origStart Offset of the first character of the text to check
     *   in the buffer
     * @param origEnd Offset of the character following the last character
     *   of the text (as per usual Java API convention)
     *
     * @return Normalized String, if any white space was removed or
     *   normalized; null if no changes were necessary.
     */
    public static String normalizeSpaces(char[] buf, int origStart, int origEnd) {
        --origEnd;

        int start = origStart;
        int end = origEnd;

        // First let's trim start...
        while (start <= end && buf[start] == CHAR_SPACE) {
            ++start;
        }
        // Was it all empty?
        if (start > end) {
            return "";
        }

        /* Nope, need to trim from the end then (note: it's known that char
         * at index 'start' is not a space, at this point)
         */
        while (end > start && buf[end] == CHAR_SPACE) {
            --end;
        }

        /* Ok, may have changes or not: now need to normalize
         * intermediate duplicate spaces. We also now that the
         * first and last characters can not be spaces.
         */
        int i = start + 1;

        while (i < end) {
            if (buf[i] == CHAR_SPACE) {
                if (buf[i + 1] == CHAR_SPACE) {
                    break;
                }
                // Nah; no hole for these 2 chars!
                i += 2;
            } else {
                ++i;
            }
        }

        // Hit the end?
        if (i >= end) {
            // Any changes?
            if (start == origStart && end == origEnd) {
                return null; // none
            }
            return new String(buf, start, (end - start) + 1);
        }

        /* Nope, got a hole, need to constuct the damn thing. Shouldn't
         * happen too often... so let's just use StringBuilder()
         */
        StringBuilder sb = new StringBuilder(end - start); // can't be longer
        sb.append(buf, start, i - start); // won't add the starting space

        while (i <= end) {
            char c = buf[i++];
            if (c == CHAR_SPACE) {
                sb.append(CHAR_SPACE);
                // Need to skip dups
                while (true) {
                    c = buf[i++];
                    if (c != CHAR_SPACE) {
                        sb.append(c);
                        break;
                    }
                }
            } else {
                sb.append(c);
            }
        }

        return sb.toString();
    }
}